Optocoupler

Optocoupler 

Footprints 

Figure 1. 4-pin SMD option 7 


.406 (10.31) 

.100 (2.54) 

R .010 (.25) 

.030 (.76) 

.406 (10.31) 

.070 (1.78) 

.315 (8.00) min .060 (1.52) 

.435 (11.05) 


.406 (10.31) 

.030 (.76) 

.100 (2.54) 

R .010 (.25) 

.100 (2.54) 

R .010 (.25) 

.030 (.76) 

.315 (8.00) min 

.435 (11.05) 

.070 (1.78) 

.060 (1.52) 

.070 (1.78) 

.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 

Figure 5. 4-pin option 8 


.472 (11.99) 

.100 (2.54) 

R .010 (.25) 

.030 (.76) 

.406 (10.31) 

.070 (1.78) 

.392 (9.95) min .060 (1.52) 

.512 (13.00) 

.030 (.76) 

.100 (2.54) 

R .010 (.25) 

.070 (1.78) 

.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 

Document Number: 83715 

www.vishay.com 

Revision 17-August-01 2–49

Figure 6. 6-pin option 8 


.472 (11.99) 

.395 (10.03) 

.030 (.76) 

.100 (2.54) 

R .010 (.25) 

.392 (9.95) min 

.512 (13.00) 

.070 (1.78) 

.060 (1.52) 

.100 (2.54) 

R .010(.25) 

.030 (.76) 

.070 (1.78) 


.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 


.395 (10.03) 

.100 (2.54) 

R .010(.25) 

.030 (.76) 

.395 (10.03) 

.070 (1.78) 

.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 


.395 (10.03) 

.030 (.76) 

.030 (.76) 

.100 (2.54) 

R .010(.25) 

.070 (1.78) 

.100 (2.54) 

R .010(.25) 

.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 

.070 (1.78) 

.315 (8.00) min 

.435 (11.05) 

.060 (1.52) 




Figure 11. 8-pin PCMCIA 

Figure 14. 16-pin PCMCIA 

R .010(.25) 

.336 (8.53) 

.336 (8.53) 

.050 (1.27) 

.014 (.36) 

.036 (.91) 

.266 (6.76) .045 (1.14) 

.356 (9.04) 

R .010(.25) 

.100 (2.54) 

Figure 12. 4-pin MINI-FLAT 

.050 (1.27) 

.014 (.36) 

.036 (.91) 

.266 (6.76) .045 (1.14) 

.356 (9.04) 

R .010 (.25) 

.270 (6.86) 

.014 (.36) 

Figure 15. 8-pin PCMCIA, heatsink 

.100 (2.54) 

.036 (.91) 

.200 (5.08) .045 (1.14) 

.290 (7.37) 

.336 (8.53) 

R .010(.25) 

Figure 13. 16-pin MINI-FLAT 

.050 (1.27) 

.086 (2.18) 

.014 (.36) 

.036 (.91) 

.266 (6.76) .045 (1.14) 

.356 (9.04) 

R .010 (.25) 

.270 (6.86) 

Figure 16. SO8A and DSO8A SMD 

.236 (5.99) 

.050 (1.27) 

.014 (.36) 

R .010 (.13) 

.036 (.91) 

.200 (5.08) .045 (1.14) 

.290 (7.37) 

.050 (1.27) 

.014 (.36) 

.036 (.91) 

.170 (4.32) .045 (1.14) 

.260 (6.6) 




Figure 17. Mini coupler 

.276 (7.01) 

R .005(.13) 

.010 (.25) 

.053 (1.35) 

.050 (1.27) 

.040 (1.02) 

.216 (5.49) 

.296 (7.52) 

.024 (.61) 

.026 (.66) 




Optocouplers in Switching Power Supplies 

The following chapters should give a full 

understanding on how to use optocouplers which 

provide protection against electric shock for designs. 

Safety standards for optocouplers are intended to 

prevent injury or damage due to electric shock 

Two levels of electrical interface are normally used: 

Reinforced, or safe insulation is required in an 

optocoupler interface between a hazardous voltage 

circuit (like an ac line) and a touchable Safety Extra 

Low Voltage (SELV) circuit. 

Basic insulation is required in an optocoupler 

interface between a hazardous voltage circuit and a 

non-touchable Extra Low Voltage (ELV) circuit. 

The most widely used insulation for optocouplers in 

switch-mode power supply is reinforced insulation 

(class II). The following information enables the 

designer to understand the safety aspects, the basic 

concept of the VDE 0884 and the design 

requirements for applications. 

VDE 0884 - Facts and Information 

Optocouplers for line-voltage separation must have 

several national standards. The most accepted 

standards are: 

D 

D 

D 

D 

UL/ CSA for America 

BSI for Great Britain 

FIMKO, SEMKO, NEMKO, DEMKO for Nordic 

countries (Europe) 

VDE for Germany 

Today, most manufacturers operate on a global 

scale. It is therefore mandatory to perform all 

approvals. 

The VDE 0884 is becoming a major safety standard 

in the world, partly due to German experts having a 

long record of experience in this field. It is therefore 

worthwhile understanding some requirements and 

methods of the VDE 0884. 

At the moment there is the drafts which is being 

circulated to set the VDE 0884 to an international IEC 

standard: IEC 47C / 199 / CD ; after voting, this draft 

will be a part of IEC 747-5. 

If design engineers work with VISHAY optocouplers, 

they will find some terms and definitions in the data 

sheets which relate to VDE 0884. These will now be 

explained: 

Rated isolation voltages: 

Vishay Telefunken 

V IO is the voltage between the input terminals and the 

output terminals. 

Note: All voltages are peak voltages! 

D V IOWM is a maximum rms. voltage value of the 

optocouplers assigned by VISHAY. This 

characterizes the long term withstand capability 

of its insulation. 

D V IORM is a maximum recurring peak (repetitive) 

voltage value of the optocoupler assigned by 

VISHAY. This characterizes the long-term 

withstand capability against recurring peak 

voltages. 

D V IOTM is an impulse voltage value of the 

optocoupler assigned by VISHAY. This 

characterizes the long-term withstand capability 

against transient over voltages. 

Isolation test voltage for routine tests is at factor 

1.875 higher than the specified V IOWM / V IORM (peak). 

A partial discharge test is a different test method to 

the normal isolation voltage test. This method is more 

sensitive and will not damage the isolation behavior 

of the optocoupler like other test methods probably 

do. 

The VDE 0884 therefore does not require a minimum 

thickness through insulation. The philosophy is that 

a mechanical distance only does not give you an 

indication of the safety reliability of the coupler. It is 

more recommendable to check the total construction 

together with the assembling performance. The 

partial discharge test method can monitor this 

more reliably. 

The following tests must be done to guarantee this 

safety requirement. 

100% test (piece by piece) for one second at a 

voltage level of specified V IOWM /V IORM (peak) 

multiplied by 1.875 * test criteria is partial discharge 

less than 5 pico coulomb. 

A lotwise test at V IOTM for 10 seconds and at a 

voltage level of specified V IOWM / V IORM (peak) 

multiplied by 1.5 for 1 minute * test criteria is partial 

discharge less than 5 pico coulomb. 

Design example: 

The line ac voltage is 380 V rms. Your application 

class is III (DIN/VDE 0110 Part 1/1.89). According to 

table 1, you must calculate with a maximum line 

voltage of 600 V and a transient over voltage of 

6000 V. 

03.99 1


Table 1. 

Recommended transient overvoltages related to ac/ dc line voltage (peak values) 

V IOWM /V IORM 

up to 

Appl. Class I Appl. Class II Appl. Class III Appl. Class IV 

50 V 350 V 500 V 800 V 1500 V 

100 V 500.V 800 V 1500 V 2500 V 

150 V 800 V 1500 V 2500 V 4000 V 

300 V 1500 V 2500 V 4000 V 6000 V 

600 V 2500 V 4000 V 6000 V 8000 V 

1000 V 4000 V 6000 V 8000 V 12000 V 

Now select the TCDT1100 from our VISHAY coupler 

program. The next voltage step of 380 V is 600 V 

(V IOWM ).The test voltages are 1600 V for the 

TCDT1100 for the routine test and 6000 V/ 1300 V for 

the sample test. 

The VDE 0884 together with the isolation test 

voltages also require very high isolation resistance, 

tested at an ambient temperature of 100°C. 

Apart from these tests for the running production, the 

VDE Testing and Approvals Institute also 

investigates the total construction of the optocoupler. 

The VDE 0884 requires life tests in a very special 

sequence; 5 lots for 5 different subgroups are tested. 

The sequence for the main group is as follows: 

D 

D 

D 

D 

D 

D 

D 

D 

Cycle test 

Vibration 

Shock 

Dry heat 

Accelerated damp heat 

Low temperature storage (normally --55°C) 

Damp heat steady state 

Final measurements. 

Finally there is another chapter concerning the safety 

ratings. This is described in VDE 0884. 

The maximum safety ratings are the electrical, 

thermal and mechanical conditions that exceed the 

absolute maximum ratings for normal operations. 

The philosophy is that optocouplers must withstand 

a certain exceeding of the input current, output power 

dissipation, and temperature for at least a weekend. 

The test time is actually 72 hours. This is a simulated 

space of time where failures may occur. 

It is the designer’s task to create his design inside of 

the maximum safety ratings. 

Optocouplers -- approved to the VDE 0884 -- must 

consequently pass all tests undertaken. This then 

enables you to go ahead and start your design. 

Layout Design Rules 

The previous chapter described the important safety 

requirements for the optocoupler itself; but the 

knowledge of the creepage distance and clearance 

path is also important for the design engineer if the 

coupler is to be mounted onto the circuit board. 

Although several different creepage distances 

referring to different safety standards, like the IEC 65 

for TV or the IEC 950 for office equipment, computer, 

data equipment etc. are requested, there is one 

distance which meanwhile dominates switching 

power supplies: This is the 8 mm spacing 

requirement between the two circuits: The hazardous 

input voltage (ac 240 power-line voltage) and the 

safety low voltage. 

This 8 mm spacing is related to the 250 V power line 

and defines the shortest distance between the 

conductive parts (either from the input to the output 

leads) along the case of the optocoupler, or across 

the surface of the print board between the solder 

eyes of the optocoupler input/ output leads, as shown 

in figure 1. The normal distance input to output leads 

of an optocoupler is 0.3”. This is too tight for the 8 mm 

requirement. The designer now has two options: He 

can provide a slit in the board, but then the airgap is 

still lower; or he can use the ”G” optocoupler from 

VISHAY. ”G” stands for a wide-spaced lead form of 

0.4” and obtains the 8 mm creepage, clearance 

distance. The type designation for this type of ”G” 

coupler is, for example: TCDT1100G. 

The spacing requirements of the 8 mm must also be 

taken into consideration for the layout of the board. 

Figures 2 and 3 provide examples for your layout. 

The creepage distance is also related to the 

resistance of the tracking creepage current stability. 

The plastic material of the optocoupler itself and the 

2 

03.99


material of the board must provide a specified 

creeping-current resistance. 

The behavior of this resistance is tested with special 

test methods described in the IEC 112. The term is 

”CTI” (Comparative Tracking Index). 

The VDE 0884 requires a minimum of a CTI of 175. 

Creepage 

path 

Clearance path 

Figure 1. Isolation creepage/ clearance path along the body 

(The creepage path is the shortest distance between conductive parts along the surface of the isolation 

material. The clearance path is the shortest distance between conductive parts.) 

0.4 ”/ 10.16 mm 

0.332 ”/ 8.2 mm 

Figure 2. Isolation creepage/ clearance path after mounting on a board (side view) 

03.99 3


Power interface area 

G 

G = 0.322 ” / 8.2 mm 

Layer 

SELV control circuit area 

Power interface area 

G 

G 

G 

SELV control circuit area 

Figure 3. ”Top view of optocoupler mounting on a board” 

(clearance on PC board: 0.322 / 8.2 mm, creepage path on PC board is 0.322 / 8.2 mm) 

Not only the solder eyes of the coupler itself on the board must have the 8 mm distance, but also all 

layers located between the SELV areas and the power interface areas. 

VISHAY Optocoupler Program 

Construction 

An optocoupler is comparable with a transformer or 

a mechanical relay; but its advantages are smaller 

dimensions, shorter switching time, no contact 

bounces, no interference caused by arcs and the 

possibility of adapting a signal already in the coupler 

for the following stage of the circuit. 

This combination together with the safety aspects 

provides outstanding advantages for use in power 

supplies. Safety factors in particular depend on the 

design, construction and selected materials. VISHAY 

optocouplers are designed with a coplanar lead 

frame, where the die are mounted side by side. A 

semi-ellipsoid with even better reflection capabilities 

is fitted over each dice. The entire system is then 

casted in a plastic material impermeable to the 

infrared range and of high di-electric strength. The 

whole system is now molded with a special mold 

compound to ensure that no external influences such 

as light or dust etc. interfere with the functioning of the 

coupler (see figure LEERER MERKER). This design 

has several advantages: The ”thickness through 

insulation”, the clearance (internally) between the 

input and the output side is fixed at 0.75 mm and is 

thus mechanically stable even under thermal 

overloads, i.e., the possibility of a short circuit caused 

by material deformation is excluded. Deviations of 

this distance during the production process are also 

excluded. These two features are the specific 

reasons why VISHAY optocouplers are 

well-accepted by manufacturers of power supplies. 

1.) External Creepage Distance 

2.) Internal Creepage Distance >4mm 

3.) 0.75 mm fixed thickness--through--insulation 

4.) Clearance path 

Figure 4. Coplanar construction (e.g., CQY80N) 

4 

03.99


Overview 

The information given in this brochure enables the 

designer to select the right optocoupler for his 

application. The previous chapters focused only on 

safety aspects. Apart from this there are other 

characteristics for the optocoupler. Table 2 enables 

the designer to select the optocoupler to suit his own 

needs. This selection should be done using the most 

important characteristics like CTR (Current Transfer 

Ratio) and devices with or without base connection. 

The designer may ask for our data sheets for detailed 

information. 

n.c. C E 

6 5 4 

B 

C 

E 

6 5 4 

6 -PIN STD Isolators 

Table 2. Devices offering (VDE 0884-tested) 

1 2 3 

A (+) C ( -) n.c. 

Without base connection 

1 2 3 

A (+) C ( -) n.c. 

With base connection 

CTR 

IC/ IF 

Base 

Connection 

> 20% 4N25(G)V 

V CE > 32 V 

Ungrouped CTR 

V CE > 50 V 

Grouped CTR 

V CE > 90 V 

Grouped CTR 

With Without With Without With Without 

> 50% CQY80N(G) TCDT1100(G) TCDT1120(G) 

> 100% 4N35(G)V TCDT1110(G) 

40 -- 80% CNY17(G)--1 TCDT1101(G) 

63 -- 125% CNY17(G)--2 TCDT1102(G) CNY75(G)A TCDT1122(G) 

100 -- 

200% 

160 -- 

320% 

G = wide space 0.4” lead form, for 8 mm PC board spacing requirements 

CNY17(G)--3 TCDT1103(G) CNY75(G)B TCDT1123(G) 

CNY17(G)--4 CNY75(G)C TCDT1124(G) 

Appendix 

Approvals List 

As mentioned before, as long there is no equivalent 

IEC--standard to the VDE 0884, optocouplers must 

still fulfill all other national safety standards. The 

copies of documents present all certificates the 

designer needs for worldwide acceptance of his 

power supply (see ANT018). All the approvals below 

are most important. If the designer needs any others, 

he must be aware that there are many agreements 

between national institutes, e.g., UL for USA is also 

accepted by CSA/Canada. 

VISHAY divides optocouplers into ”coupling 

systems”. Each coupling system represents the 

same technology, materials etc. The coupling 

systems are indicated with capital letters and each 

coupler is marked with this coupling system indicator 

letter. The certificates at least also refer to the 

systems and list all subtypes to the related coupling 

system. The user is able to find his selected coupler 

on the certificate. 

03.99 5


Safety Standard Approval List 

UL CSA VDE BSI NORDIC Std. 

Part Numbers 

UL 

1577 - 

single 

Protection 

UL 

1577 - 

double 

Protection 

C -UL 

1577- 

double 

Protection 

Safety standard according to 

VDE 0884 

IEC950/ EN60950; 

IEC65/ EN60065 

BSI 

EN60950 

(BS 7002/ 

IEC950) 

BSI 

EN60065 

(BS 415/ 

IEC65) 

FIMKO 

EN60950/ IEC950, 

EN60065/ IEC65 

Creepage 

Distance 

Thickness 

of 

Insulation 

A, C, H, J, K, U U A+C H, J, K U A, C, H, J, K, U A C U 

Inter- 

Exter- 

nal 

nal 

Coupling Systems 1) 

File Numbers 

E--76222 Card A+B 094778 076814 115667 7402 7081 12399 12398 11027 11992 mm mm mm 

4N25 up to 4N37 ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

4N25GV ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

4N25V ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

4N32/ 4N33 ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

4N33V ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

4N35GV ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

4N35V ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

CNY17 -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

CNY17G -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

CNY64 -Series ¯ ¯ >4,0 9.0 >3,0 

CNY65 -Series ¯ ¯ >4,0 14.0 >3,0 

CNY65EXI ¯ ¯ >4,0 14.0 >3,0 

CNY66 ¯ ¯ >4,0 17.0 >3,0 

CNY74 -2H/ CNY74 -4H ¯ ¯ >4,0 6.0 0.75 

CNY75 -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

CNY75G -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

CQY80N ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

CQY80NG ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

K1150PG ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

K3010P -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

K3010PG -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

K3020P -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

K3020PG -Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

K814P/ K824P/ K844P ¯ ¯ ¯ >4,0 6.0 0.75 

K815P/ K825P/ K845P ¯ ¯ ¯ >4,0 6.0 0.75 

K817P -Series ¯ ¯ ¯ >4,0 6.0 0.75 

K827PH/ K847PH ¯ ¯ ¯ >4,0 6.0 0.75 

MCT6H/ MCT62H ¯ ¯ ¯ >4,0 6.0 0.75 

TCDT1100 Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCDT1100G Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

TCDT1110 ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCDT1110G ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

TCDT1120 Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCDT1120G Series ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

TCED1100 -TCED4100 ¯ ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCED1100G - 

TCED4100G 

¯ ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

TCET1100 -TCET4100 ¯ ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCET1100G - 

TCET4100G 

¯ ¯ ¯ ¯ ¯ ¯ ¯ >4,0 8.0 0.75 

TCET1600 -TCET4600 ¯ ¯ ¯ ¯ ¯ ¯ ¯ >4,0 6.0 0.75 

TCET1600G - 

TCET4600G 

¯ ¯ ¯ ¯ >4,0 8.0 0.75 

1) Coupling Systems: Each coupling system represents the same technology, materials etc. The coupling 

systems are indicated with capital letters an each coupler is marked with this coupling system indicator letter. 

The bold certificates at least also refer to the systems and list all subtypes to the related coupling system. The 

user is able to track his selected coupler on the certificate. 

6 

03.99


General Description 

Basic Function 

In an electrical circuit, an optocoupler ensures total 

electric isolation, including potential isolation, as in 

the case of a transformer, for instance. 

In practice, this means that the control circuit is 

located on one side of the optocoupler, i.e., the 

emitter side, while the load circuit is located on the 

other side, i.e., the receiver side. Both circuits are 

electrically isolated by the optocoupler (figure 5). 

Signals from the control circuit are transmitted 

optically to the load circuit, and are therefore free of 

retroactive effects. In most cases, this optical 

transmission is realized with light beams whose 

wavelengths span the red to infrared range, 

depending on the requirements applicable to the 

optocoupler. The bandwidth of the signal to be 

transmitted ranges from a dc voltage signal to 

frequencies in the MHz band. An optocoupler is 

comparable to a transformer or relay. Besides having 

smaller dimensions in most cases, the advantages of 

optocouplers compared to relays are the following: it 

ensures considerably shorter switching times, no 

contact bounce, no interference caused by arcs, no 

mechanical wear and the possibility of adapting a 

signal, already in the coupler, to the following stage 

in the circuitry. Thanks to all these advantages, 

optocouplers are outstandingly suitable for circuits 

used in microelectronics and also in data processing 

and telecommunication systems. Optocouplers are 

used to an increasing extent as safety tested 

components, e. g., in switchmode power supplies. 

Design 

An optocoupler has to fulfill 5 essential requirements: 

D 

D 

D 

D 

D 

Good insulation behavior 

High current transfer ratio (CTR) 

Low degradation 

Low coupling capacitance 

No uncontrolled function by field strength 

influences 

These factors are essentially dependent on the 

design, the materials used and the corresponding 

chips used for the emitter/receiver. 

Vishay has succeeded in achieving a design with 

optimized insulation behavior and good transfer 

characteristics with their Co--planar technology.The 

basic function of an optocoupler is to isolate the input 

from the output by means of an insulation material. 

In most optocouplers, the emitter and detector chips 

face each other on seperate lead frames. As a result, 

the distance between these two chips may vary, 

causing reliability problems. TELEFUNKEN’S 

co--planar technology ensures that there is a stable 

distance between the emitter and detector chips. The 

fixed thickness--through--insulation of 0.75 mm 

provided by TELEFUNKEN’S co--planar 

optocouplers is larger than competing devices and 

provides better safety and protection against 

electrical shock (see figure 1/2).TELEFUNKEN 

builds in additional reliability to these devices by using 

a special white molding compound to protect the 

coupler system against ambient light and dust. This 

solution does not require an additional internal 

reflector any longer. 

The mechanical clearance between the emitter and 

receiver is 0.75 mm and is thus mechanically stable 

even under thermal overloads, i.e., the possibility of 

a short circuit caused by material deformation is 

excluded. This is important for optocouplers which 

have to fulfill strict safety requirements (VDE/UL 

specifications), see VDE0884 Facts and Information. 

Thanks to their large clearance these couplers have 

a very low coupling capacity of 0.2 pF. Couplers with 

conventional designs, i.e., where the emitter and 

receiver are fitted ”face-to-face”(see figure 2), have 

higher coupling capacitance values by a factor of 1.3 

- 2. Attention must be paid to the coupling 

capacitance in digital circuits in which steep pulse 

edges are produced which superimpose themselves 

on the control signal. With a low coupling 

capacitance, the transmission capabilities of these 

interference spikes are effectively suppressed 

between the input and output because a coupler 

should only transmit the effective signal. This 

capability of suppressing dynamic interferences is 

commonly known as “common-mode rejection”. 

03.99 1


1.) External Creepage Distance 

2.) Internal Creepage Distance >4mm 

3.) 0.75 mm fixed thickness--through--insulation 

4.) Clearance path 

Figure 1. Coplanar Construction Principle 

(e.g., CQY80N) 

potential. The manufacturer should create suitable 

protective measures in this case. Using Vishay’s 

optocouplers, such protective measures are not 

necessary thanks to their perfect design. 

The degradation of an optocoupler, i.e., impairment 

of its CTR over a finite period, depends on two 

factors. On the one hand, it depends on the emitter 

element due to its decreasing radiation power while, 

on the other hand, it depends on ageing or 

opaqueness of the synthetic resin which must 

transmit the radiation from the emitter to the receiver. 

A decrease in the radiation power can be primarily 

ascribed to thermal stress caused by an external, 

high ambient temperature and/or high a forward 

current. In practice, optocouplers are operated with 

forward current of 1 to 30 mA through the emitting 

diode. In this range, degradation at an average 

temperature of 40°C is less than 5% after 1000 h. In 

general, an optocoupler’s life time is a period of 

100.000 h, i.e, the CTR should not have dropped 

below 50% of its value at 0 hours during this time (see 

figure 9). 

Figure 3. Functions of parasitic field effect transistor as a 

result of failure (latch-up) in the 

phototransistor of couplers 

Figure 2. 

Face to Face Construction Principle 

Due to the special design of these couplers, the 

receiver surface is outside the area of the direct field 

strength. Field strength is produced when there is a 

voltage potential between the coupler’s input and 

output. It causes the migration of positive ions to the 

transistor’s surface. Positive ions perform on the 

base in the same way as a gate voltage applied to an 

n-channel FET transistor (see figure 8). 

If inversions occur on the surface, the phototransistor 

becomes forward-biased, causing an inadmissible 

residual collector-emitter current. As a result, 

controlled functioning of the coupler is no longer 

guaranteed (figure 8). This effect occurs mainly 

whenever the receiver is within the field strength 

Average Percent of Initial CTR 

15918 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

Leadership in IR technology 

D The die’s molecular structure 

D Mesa technology 

D Special bond layout results in an 

homogenuous current distribution 

D Special rear metalization 

0 20000 40000 60000 80000 100000 

Life Test Hours 

Figure 4. Degradation under typical operating 

conditions with reference to the CQY80N 

T j = 65°C 

I F = 60mA 

T j = 125°C 

I F = 60mA 

2 

03.99


Technical Description - 

Assembly 

Emitter 

Emitters are manufactured using the most modern 

Liquid Phase Epitaxy (LPE) process. By using this 

technology, the number of undesirable flaws in the 

crystal is reduced. This results in a higher quantum 

efficiency and thus higher radiation power. 

Distortions in the crystal are prevented by using 

mesa technology which leads to lower degradation. 

A further advantage of the mesa technology is that 

each individual chip can be tested optically and 

electrically even on the wafer. 

Detector 

Vishay detectors have been developed so that they 

match perfectly to the emitter. They have low 

capacitance values, high photosensitivity and are 

designed for an extremely low saturation voltage. 

Silicon nitride passivation protects the surface 

against possible impurities. 

Assembly 

The components are fitted onto lead frames by fully 

automatic equipment using conductive epoxy 

adhesive. Contacts are established automatically 

with digital pattern recognition using the well-proven 

thermosonic technique. In addition to optical and 

mechanical checks, all couplers are measured at a 

temperature of 100°C on a short/open 

testequipment. 

Conversion Tables - Optoelectronic General 

Table 1. Corresponding radiometric and photometric definitions, symbols and units (DIN 5031, Part 1, 3) 

Radiometric Units 

Photometric Units 

Unit Symbol Unit Unit Symbol Unit 

Note 

Radiant flux, F e Watt, W Luminous flux F v lumen, lm Power 

Radiant power 

Radiant exitance, 

Exitance 

M e W/m 2 Luminous emittance M v lm/m 2 Output power per 

unit area 

(Radiant) intensity I c W/sr (Luminous) intensity I v Candela, 

cd, lm/sr 

Output power per 

unit solid angle 

Radiant sterance, L e 

Luminance 

L v cd/m 2 Output power per 

Radiance 

W (Brightness sterance) 

unit solid angle 

sr * m 2 

and emitting areas 

Radiant incidance, 

Irradiance 

E e W/m 2 Illuminance E v lm/m 2 

Lux, lx 

Input power per 

unit area 

Radiant energy Q e Ws Luminous energy Q v lm s Power time 

Irradiation H e Ws/m 2 Illumination H v lm s/m 2 Radiant energy or 

luminous energy 

per unit area 

03.99 3


Measurement Techniques 

Introduction 

The characteristics given in the optocoupler‘s data 

sheets are verified either by 100% production tests 

followed by statistic evaluation or by sample tests on 

typical specimens. Possible tests are the following: 

Measurements on emitter chip 

Measurements on detector chip 

Static measurements on optocoupler 

Measurement of switching characteristics, cut-off 

frequency and capacitance 

Thermal measurements 

The basic circuits used for the most important 

measurements are shown in the following sections, 

although these circuits may be modified slightly to 

cater for special measurement requirements. 

Measurements on Emitter Chip 

Forward- and Reverse Voltage 

Measurements 

The forward voltage, V F, is measured either on a 

curve tracer or statically using the circuit shown in 

figure 10. A specified forward current (from a 

constant current source) is passed through the 

device and the voltage developed across it is 

measured. 

To measure the reverse voltage, V R , a 10 A reverse 

current from a constant current source is applied to 

the diode (figure 11) and the voltage developed 

across it is measured on a voltmeter of extremely 

high input impedance (≥10 M). 

V S = 5 V 

I = 50 mA 

100 mA 

constant 

V F 

V 

Figure 1. 

V S = 80 V 

( > V R max ) 

V R 

I = 10 A 

constant 

V 

R i > 10 k 

94 8205 

R i > 10 M 

94 8206 

Figure 2. 

03.99 1


Measurements on Detector Chip 

V CEO and I CEO Measurements 

The collector-emitter voltage, V CEO , is measured 

either on a transistor curve tracer or statically using 

the circuit shown in figure 12. 

The collector dark current, I CEO , must be measured 

in complete darkness (figure 13). Even ordinary 

daylight illumination might cause wrong 

measurement results. 

V S = 100 V 

( > V CEO ) 

I C =1mA 

constant 

Static Measurements 

To measure the collector current, I C (figure 14), a 

specified forward current, I F , is applied to the lR 

diode. Voltage drop is then measured across a low 

emitter resistance. 

In the case of collector-emitter saturation voltage, 

V CEsat (figure 15), a forward current, I F , is applied to 

the IR diode and a low collector current, I C , in the 

phototransistor. V CEsat is then measured across 

collector and emitter terminals. 

V S = 5 V 

I F = 5mA 

10 mA 

constant 

V S = 5 V 

I C 

E < 100 lx 

V CEO 

V 

R i 1M 

1 

mV 

R j = 10 k 

96 12367 

96 11696 

Figure 3. 

Figure 5. 

V S = 20 V 

V S = 5 V 

V S = 5 V 

E = 0 

I CEO 

I F = 10mA 

constant 

I C =1mA 

constant 

10 k mV 

R i = 1 M 

V CEsat 

V 

R j 1M 

96 11695 

94 8218 

Figure 4. 

Figure 6. 

2 

03.99


Switching Characteristics 

Definition 

Each electronic device generates a certain delay 

between input and output signals as well as a certain 

amount of amplitude distortion. A simplified circuit 

(figure 16) shows how the input and output signals of 

optocouplers can be displayed on a dual-trace 

oscilloscope. 

V S 

Improvements of Switching 

Characteristics of Phototransistors 

and Darlington Phototransistors 

With normal transistors, switching tunes can be 

reduced if the drive signal level and hence the 

collector current is increased. Another time reduction 

(especially in fall time t f ) can be achieved by using a 

suitable base resistor. However, this can only be 

done at the expense of a decreasing CTR. 

I F 

96 11697 

GaAs-Diode 

Channel I 

Channel II 

Figure 7. 

The following switching characteristics can be 

determined by comparing the timing of the output 

current waveform to that of the input current 

waveform (figure 17). 

96 11698 

I F 

0 

t 

t p 

t p 

pulse duration 

t d 

delay time 

I C 

t r 

rise time 

t on (= t d + t r ) turn-on time 

100% 

t s 

storage time 

90% 

t f 

fall time 

t off (= t s + t f ) turn-off time 

10% 

0 

t r 

t d 

t on 

t s t f 

t 

Figure 8. 

t off 

03.99 3


Cut-off Frequency Measurement 

The cut-off frequency is the frequency at which the coupler of the small signal current transfer ratio has 

decreased to 1 22 

of its lowest frequency value. 

50 Ω 

Channel A 

+V CC 

Channel B 

50 Ω R L 

GND 

Figure 9. Test circuit for cut-off frequency 

15941 

Coplanar 6 PIN e.g.: TCDT1100 Series 

Relative AC Output ( dB ) 

5 

0 

–5 

–10 

–15 

–3 dB 

CTR=100% 

CTR=150% 

CTR=65% 

–20 

V CC =5V, I C =5mA, 

R L =100 

–25 

1 10 100 1000 

15943 

f – Frequency ( kHz ) 

Figure 10. Rel. Current Transfer Ratio / Frequency 


5 

0 

–5 

–10 

–15 

–3 dB CTR=65% 

CTR=100% 

CTR=150% 

–20 


R L =1k 

–25 

1 10 100 1000 

15942 



Before applying an AC test signal to the coupler 

input terminals , the IR diode has to be baised 

with a DC current in order to establish a work– 

point in the linear region of the phototransistor’s 

output diagram. Then a small sinusoidal current 

signal of 1000Hz is superimposed to the DC bais 

current. The output to input AC signal ratio i C /i F is 

measured and set to 0 dB. After this the 

frequency of the input signal is increased and the 

i C /i F ratio is recorded and plotted. Depending on 

the coupler’s DC current transfer ratio and the 

test conditions, the AC signal ratio will drop at 

higher frequency levels. The frequency value at 

–3 dB signal level is called the cut–off frequency. 

Coplanar 4 PIN e.g.: TCET1100 Series 


5 

0 

–5 

–10 

–15 

–3 dB 

CTR=100% 

CTR=180% 

CTR=65% 

–20 


R L =100 

–25 

1 10 100 1000 

15945 




5 

0 

–5 

–10 

–15 

–3 dB CTR=65% 

CTR=100% 

CTR=180% 

–20 


R L =1k 

–25 

1 10 100 1000 

15944 



4 

03.99

Application Examples 

Optocouplers in IC Logic Design 

Two examples of dimensioning a TTL logic circuit 

employing an optocoupler, Series TCET110X or 

K817P. 

a) Supply voltage: V CC = 5 V 

b) Operation temperature range: –20°C to +60°C 

c) Service life of application: 10 years 

The following conditions are intended to apply to both 

examples conjointly: 

Example 1 

Phototransistor wired to emitter resistor. 

I F 

R V 

TTL 


A voltage V L at R L resistor of V IH 2 V is 

necessary in order to attain a safe high state at the 

output. This needs to be generated by the collector 

current Ic of the phototransistor. 

In the case of the TTL output at the input of the optocoupler 

the current should remain I OL < = 16 mA. 

The CTR value of 50% results in maximum output 

current I C for the optocoupler of 8 mA. 

V CC 

V CC 

This allows the minimum value to be determined 

for R 

TCET1100 IC 

L . 

K817P 

R L V IH 

I L 

2V 

8mA 250 

I IL I IH 

I If for example R L TTL 

L = 390 is selected and 20% safety 

is computed to the minimum V IH in respect of the high 

R L V L 

state (V IH + V IH 20% = 2.4 V), this will then permit 

15096 

I C , I F and the dropping resistor R V at the input of the 

optocoupler to be determined, 

I C I L 2.4 V 6.15 mA 

390 

– I F 

6.15 mA 

12.3 mA 

CTR 

With V F = 1.2 V, (the forward voltage of the I R diode) 

and V OL < 0.4 V for the TTL output follows 

R V V CC –V F –V OL 

12.3 mA 276 , R V 270 

For dimensioning purposes, a typical CTR value of 

100% at I F = 10 mA is selected. Within the 

temperature range of –20°C to +60°C the CTR 

undergoes change between +12% and –17% (see 

data sheet). The –17% reduction is critical as applied 

to functioning of the circuit. Assuming a 10-year 

service life period of the interface circuit, allowance 

needs to be made for additional CTR reduction of 

approximately 20% on account of degradation. 

Making an additional tolerance allowance of 

approximately –25% for the CTR will result in a safe 

minimum value of approximately 50%. 

CTRmin = 100% (0.83) (0.80) (0.75) = 49.8% 

For a defined low state at the output of the 

optocoupler the voltage V L at R L must be 

V IL 0.8 V and current I IL (I ILmax = 1.6 mA) must be 

capable of flowing through R L from the TTL input. 

Owing to the phototransistor in this case being 

blocked at the output of the optocoupler and I CEO 

maximum 200 nA (at approximately 60°C), I L – I IL 

setting can proceed practically without any error. 

This results in the following maximum value of R L : 

R L 

V IL 

I IL 

0.8 V 

With I L = I C + I IH and I IH for standard TTL being 

maximum 40 A, I L = I C can be assumed without any 

essential error. 

Applying this dimensioning, the TTL interface with 

the optocoupler is able to transmit signals having a 

frequency of > 50 kHz or a transmission rate of 

> = 100 kbit/s. 

In the same way, an interface is dimensioned with the 

optocoupler for other logical families, e.g., LSTTL or 

HCMOS, HCTMOS components. All that needs to be 

done is to work the corresponding limit values V IH , 

V OH , I IL , I OL , etc., into the computation for the 

relevant family. 

If use is made of LSTTL or HCTMOS components 

this will also bring about an essential reduction in 

current consumption. 

03.99 5


Example 2: 

Phototransistor wired to collector resistor 

I F 

R V 

TTL 

V CC 

TCET1100 

K817P 

I C 

V CC 

I L 

R L 

I IL 

I IH 

TTL 

V IL , V IH 

15097 

The CTR is determined applying the same 

calculation – 50% – as that given in example 1. In this 

example dimensioning of the interface is launched 

from the high state at the output of the optocoupler. 

In the high state a non–operate current of the I IH – of 

maximum 40 A – may flow in the TTL input. If R L 

selection is too high, the entire non–operate current 

= I CEO + I IH may produce such a voltage drop 

through the RL that the critical V IH voltage (minimum 

= 2 V), is not attained. 

This results in the following: 

R L V CC–V IL 

I Cmax –I IL 

5 V–0.8 V 

6.4 mA 656 

To select the value for R L the following should be 

observed. 

Proceeding from the voltage V IL = 0.8 V the 

phototransistor is on the limits of saturation. 

Owing to the voltage V CE being relatively unstable in 

this state, dimensioning should be selected in such 

a way that the phototransistor is in full saturation. 

From the diagram V CEsat vs. I C in TCET110X data 

specification sheet proceeding from a CTR reduced 

by 50% and for I C < 5 mA follows V CEsat < 0.5 V 

I Cmax is now reduced to approximately 4 mA and for 

the minimum R L follows, 

R L 

V CC–V CEsat 

5 

V–0.5 V 

4mA–1.6mA 2.4 mA 1875 

If a suitable value is selected for the resistor R L it is 

possible to determine R V at the input. 

Example for R L = 5.1 k follows 

R L 

V CC–V IH 

I CEO I IH 

5V–2V 74.6 k 

40.2 A 

I L V CC–V CEsat 

R L 

I C = I IL + I L = 2.68 mA 

5.5 V 1.08 mA, 

5.1 k 

or if another + 20% safety is added to the V IH voltage, 

and with CTR = 25% 

I F = I C / CTR = 10.72 mA 

R L V CC –(V IH V IH 20 100) 

I CEO I IH 

5V–2.4V 64.7 k 

40.2 A 

For calculating the smallest usable R L –value 

I Cmax = 8 mA is assumed as in example 1 and use is 

made of the low state of the optocoupler output. In 

this circuit the current I IL of the TTL input flows 

through the phototransistor in such a way that the 

following applies: I C = I L + I IL . 

R V V CC–V F –V OL 

10.72 mA 317 , R V 330 

This interface circuit can be used for transmission 

rates of up to about 28 kbit/s The fact that 

considerably lower transmission rates are possible 

here compared with the circuit given in example 1 is 

partly due to the saturation state of the 

phototransistor and to a large extent to the higher 

value required for R L . 

6 

03.99



AC Input Compatible Optocoupler 

Introduction 

With the rapid penetration and diversification of 

electronic systems, demand for optocouplers is 

strengthening. Most popular are products featuring 

compact design, low cost, and high added value. To 

meet the market needs, Vishay is expanding the 

optocoupler. This application note focuses on optocouplers 

compatible with AC input, and covers 

configuration, priciples of operation, and application 

examples. 

Configuration 

(Internal PIN Connection Diagram) 

C 

4 3 

1 2 

A,K 

E 

A,K 

Figure 14. TCET1600 Series / K814P Series 

12710 

Figure14 shows the internal pin connection of the AC 

input compatible optocoupler TCET1600 Series / 

K814P Series, and Figure15, of the optocoupler 

TCET1100Series / K817P Series. The most 

significant difference is that the TCET1600Series / 

K814P Series incorporates an input circuit with two 

Emitters connected in reverse parallel. In the optocoupler 

TCET1100Series / K817P Series, one 

Emitter is connected in the input circuit so that the 

Emitter emits light to provide a signal when a current 

flows in one direction (1–>2 in Figure15) (one– 

direction input type). 

However, in the configuration shown in Figure14, 

when a current flows in direction 1 to 2, Emitter1 

emits light to send a signal, and when it flows from 2 

to 1, Emitter2 emits light to send a signal 

(bidirectional input type). Namely, even if the voltage 

level between 1 and 2 varies, and the positive and 

negative polarities are changed, either of two 

Emitters emits light to send a signal. This means that 

the one–direction input optocoupler permits DC input 

only, while the bidirectional input type permits AC 

input as well. Therefore, the TCET1600 Series / 

K814P Series is described as an AC input 

compatible optocoupler. 

The next section describes the status of output 

signals when Vac power is directly input to an AC input 

compatible optocoupler TCET1600 Series / 

K814P via a current limit resistor. 

4 

3 

1 

2 

12590 

Figure 15. TCET1100 Series / K817P Series 

03.99 7



Example 1: AC–DC converter 

V CC 

V CC 

Line 

Voltage 

Line 

Voltage 

+ 

0 

– 

+ 

0 

15100 

+ 

0 

– 

15099 

Figure 16. AC input compatible optocoupler 

(bidirectional input) 

Figure 17. Conventional optocoupler 

( one–direction input) 

( Full–wave rectification by means of diode bridge) 

Example 2: Detection of a telephone bell signal 

Ring Line 

Ring Line 

+ 

0 

– 

15101 

+ 

0 

– 

+ 

0 

15102 




( one–direction input) (rectified by CR circuit) 

Example 3: Sequencer circuit input section 

Common 

AC Line 

15103 

AC Line 

Common 

15104 




( one–direction input) 

( Full–wave rectified by diode bridge) 

8 

03.99


Programmable Logic Controller Example 

Purpose: in–out interface 

K814P 

15094 

03.99 9


Triac Optocoupler, K3020P(G) Series 

Non Zero Crossing Type 

V IN 

47Ω 

Load 

47Ω 

AC voltage 

R F 

0.033µF 

47Ω 

Microwave Oven with Grill 

Magnetron Thermo–Switch 

Door–Open Monitor Switch 

H.V. 

Transformer 

Magnetron 

Tube 

Oven 

Cavity 

Lamp 

H 

Grill 

Heater 

M 

Blower Motor 

Turntable 

Motor 

AC 

voltage 

50/ 60Hz 

Door–Detector Circuit 

Weight Sensor 

Microcontroller 

Gas Sensor 

Control Panel 

15093 

10 

03.99


Automatic Washing Machine 

R T 

Input/ Settings 

TH 1 

Manual/ Auto Start 

I F 

Water Flow Switching 

M 

R T 

Spin Time 

Discharge 

Water 

Valve 

TH 2 

R T 

TH 3 

I F 

Micro– 

processor 

Rinse Cycle Numbers 

Wash Time 

Mode Detector 

I F 

Intake 

Water 

Valve 

R T 

TH 4 

I F 

Microprocessor 

Power 

Supply 

AC Input 


Voltage/ AC 

15092 

03.99 11

How to Use Optocoupler Normalized Curves 

Appnote 45 

by Bob Krause 

An optocoupler provides insulation safety, electrical noise isolation, 

and signal transfer between its input and output. The insulation 

and noise rejection characteristics of the optocoupler are 

provided by the mechanical package design and insulating 

materials. 

A phototransistor optocoupler provides signal transfer between 

an isolated input and output via an infrared LED and a silicon 

NPN phototransistor. 

When current is forced through the LED diode, infrared light is 

generated that irradiates the photosensitive base-collector junction 

of the phototransistor. The base-collector junction converts 

the optical energy into a photocurrent which is amplified by the 

current gain (HFE) of the transistor. 

The gain of the optocoupler is expressed as a Current Transfer 

Ratio (CTR), which is the ratio of the phototransistor collector 

current to the LED forward current. The current gain (HFE) of 

the transistor is dependent upon the voltage between its collector 

and emitter. Two separate CTRs are often needed to 

complete the interface design. The first CTR, the non-saturated 

or linear operation of the transistor, is the most common specification 

of a phototransistor optocoupler and has a Vce of 10 

volts. The second is the saturated or switching CTR of the coupler 

with a Vce of 0.4 volts. Figures 1 and 2 illustrate the Normalized 

CTR CE for the linear and switching operation of the 

phototransistor. Figure 1 shows the Normalized Non-Saturated 

CTR CE operation of the coupler as a function of LED current 

and ambient temperature when the transistor is operated in the 

linear mode. Normalized CTR CE(SAT) is illustrated in Figure 2. 

The saturated gain is lower with LED drive greater than 10 mA. 

Figure 1. Normalized CTR versus I F and T amb 

Normalized CTR 

2.0 

1.5 

1.0 

0.5 

Ta = 25°C 

Ta = 50°C 

Ta = 70°C 

Ta = 100°C 

Normalized to : 

If = 10 mA, Vce =10V 

Ta = 25°C 

0.0 

.1 1 10 100 

IF - LED Current - mA 

Figure 2. Normalized saturated CTR 

Normalized CTR 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

.1 1 10 100 


The following design example illustrates how normalized 

curves can be used to calculate the appropriate load resistors. 

Problem 1. 

Ta = 25°C 

Ta = 50°C 

Ta = 70°C 

Ta = 100°C 

Using an IL1 optocoupler in a common emitter amplifier (Figure 

3) determine the worst case load resistor under the following 

operation conditions: 

Figure 3. IL1 to 74HC04 interface 

I 

F 

V CC 

Vce(sat) = 0.4V 

Normalized to: 

If = 10 mA. Vce =10V 

Ta = 25°C 

HC04 

T amb =70°C, I F =2 mA, V OL =0.4 V, Logic load =74HC04 

IL1 Characteristics: 

CTR CE(NON SAT) =20% Min. at T amb =25°C, I F =10 mA, V CE =10 V 

Solution 

Step 1. Determine CTR CE(SAT) using the normalization factor 

(NF CE(SAT) ) found in Figure 2. 

R 

L 

V OL 




Figure 4. Normalized saturated CTR 

Figure 5. Optocoupler/logic interface with R BE resistor 

Normalized CTRcb 

1.5 

1.0 

0.5 

SCTRcb-25 

SCTRcb-50 

SCTRcb-70 

SCTRcb-100 


If = 10mA,Ta = 25°C 

Vcb = 9.3V 

I 

F 

I 

CB 

V CC 

R 

L 

HC04 

V O 

0.0 

.1 1 10 100 

CTR CE(SAT) = CTR CE(NON SAT) NF CE(SAT) (1) 

CTR CE(SAT) = 20% * 0.36 

CTR CE(SAT) = 7.2% 

If - LED Current - mA 

Step 2. Select the minimum load resistor using the following 

equation: 

R 

V CC – V OL 

L( MIN ) = ------------------------------------------------ 

CTR CE( SAT ) I 

------------------------------------- F – I L 

100% 

R 5 V – 0.4 V 

L( MIN ) = --------------------------------------------------- 

(------------------------------ 0.072 )2mA– 

50 µA 

100% 

R L(MIN) =48.94 KΩ, select 51 KΩ ±5% 

The switching speed of the optocoupler can be greatly 

improved through the use of a resistor between the base and 

emitter of the output transistor. This is shown in Figure 5. This 

resistor assists in discharging the charge stored in the base to 

emitter and collector to base junction capacitances. When such 

a speed-up technique is used the selection of the collector load 

resistor and the base-emitter resistor requires the determination 

of the photocurrent and the HFE of the optocoupler. 

The photocurrent generated by the LED is described by the 

CTR CB of the coupler. This relationship is shown in Equations 3 

and 4. Equation 5 shows that CTR CE is the product of the 

CTR CB and the HFE. The HFE of the transistor is easily determined 

by evaluating Equation 4, once the CTR CE(SAT) and 

CTR CB are known. The Normalized CTR CB is shown in Figure 6. 

Equations 5, 6, and 7 describe the solution for determining the 

R BE that will permit reliable operation. 

(2) 

R BE 

Figure 6. Normalized CTR CB versus LED current 

Normalized CTRcb 

1.5 

1.0 

0.5 

CT CB = 

I CB = 

SCTRcb-25 

SCTRcb-50 

SCTRcb-70 

SCTRcb-100 


If = 10mA,Ta = 25 C 

Vcb = 9.3V 

0.0 

.1 1 10 100 

-------- 

I CB 100% 

I F 

I 

CTR CB 

F ----------------- 

100% 

CTR CE( SAT ) = CTR CB HFE ( SAT ) 

CTR 

HFE CE( SAT ) 

( SAT ) = ------------------------------- 

CTR CB 

R 

V be 

BE = ---------------------- 

I CB – I BE 

If - LED Current - mA 

(3) 

(4) 

(5) 

(6) 

(7) 

R BE = 

V BE HFE ( SAT ) R 

---------------------------------------------------------------------------------------------- 

L 

I CB HFE ( SAT ) R L – [ V CC – V CE( SAT ) ] 

(8) 

CTR 

V CE NF 

BE ----------------------------------------------- CE( SAT ) R L 

CTR 

R CB NF CB 

BE = ------------------------------------------------------------------------------------------------------------------ 

I F CTR CE NF CE( SAT ) R 

-------------------------------------------------------------- L – [ V CC – V CE( SAT ) ] 

100% 

(9) 




Problem 2. 

Using an IL2 optocoupler in the circuit shown in Figure 6, determine 

the value of the collector load and base-emitter resistor, 

given the following operational conditions: 

T amb =70°C, I F =5 mA, V OL =0.4 V, Logic load =74HC04 

IL2 Characteristics: 

CTR CE =100% at T amb =25°C, V CE =10 V, I F =10 mA 

CTR CB = 0.24% at T amb =25°C, V CB =9.3 V, I F =10 mA 

Solution 

Step 1. Determine CTR CE(SAT) , and CTR CB . 

From Figure 2 the CTR CE(SAT) =55%, [NF CE(SAT) =0.55] 

From Figure 6 the CTR CB = 0.132%, [NF CB =0.55] 

Step 2. Determine R L . 

From Equation 2 R L =1.7 KΩ 

Select R L = 3.3 KΩ 

Step 3. Determine R BE , using Equation 9. 

0.65V -----------------------------------3.3KΩ 

( 100% )( 0.55) 

R BE = ------------------------------------------------------------------------------------------------------------- 

( 0.24% )( 0.55) 

(------------------------------------------------------------------------- 5mA) ( 100% )( 0.55) ( 3.3KΩ) 

– [ 5V – 0.4V ] 

( 100% ) 

R BE =199 KΩ, select 220 KΩ 

(10) 

Using a 3.3 kΩ collector and a 220 KΩ base-emitter resistor 

greatly minimize the turn-off propagation delay time and pulse 

distortion. The following table illustrates the effect the R BE has 

on the circuit performance. 

I F =5 mA, V CC =5 V 

R L =3.3 KΩ 

R BE =∞ Ω 

t delay 1 µs 2 µs 

t rise 4 µs 5 µs 

t storage 17 µs 10 µs 

t fall 5 µs 12 µs 

t phl 3.5 µs 7 µs 

t plh 22 µs 12 µs 

Pulse 

Distortion 

50 µs pulse 

37% 10% 

R L =3.3 KΩ 

R BE =220 KΩ 

Not only does this circuit offer less pulse distortion, but it also 

improves high temperature switching and lower static DC 

power dissipation and improved common mode transient 

rejection. 




Dual Channel ILD1/2/5 

Quad Channel ILQ1/2/5 

Phototransistor 


FEATURES 

• Current Transfer Ratio at I F =10 mA 

ILD/Q1, 20% Min. 

ILD/Q2, 100% Min. 

ILD/Q5, 50% Min. 

• High Collector-Emitter Voltage 

ILD/Q1: BV CEO =50 V 

ILD/Q2, ILD/Q5: BV CEO =70 V 

• Field-Effect Stable by TRansparent IOn Shield 

(TRIOS) Isolation Test Voltage, 5300 V RMS 

• Underwriters Lab File #E52744 

• V VDE 0884 Available with Option 1 

D E 

Maximum Ratings (Each Channel) 

Emitter 

Reverse Voltage .............................................. 6.0 V 

Forward Current ............................................60 mA 

Surge Current .................................................. 2.5 A 

Power Dissipation........................................ 100 mW 

Derate Linearly from 25°C...................... 1.3 mW/°C 

Detector 

Collector-Emitter Reverse Voltage 

ILD/Q1 ............................................................ 50 V 

ILD/Q2, ILD/Q5................................................ 70 V 

Collector Current ............................................50 mA 

Collector Current (t

Characteristics 

Parameter Symbol Min. Typ. Max. Unit Condition 

Emitter 

Forward Voltage V F — 1.25 1.65 V I F =60 mA 

Reverse Current I R — 0.01 10 µA V R =6.0 V 

Capacitance C 0 — 25 — pF V R =0 V, f=1.0 MHz 

Thermal Resistance, Junction to Lead R THJL — 750 — K/W — 

Detector 

Capacitance C CE — 6.8 — pF V CE =5.0 V, f=1.0 MHz 

Leakage Current, Collector-Emitter I CEO — 5.0 50 nA V CE =10 V 

Saturation Voltage, Collector-Emitter V CESAT — 0.25 0.4 — I CE =1.0 mA, I B =20 µA 

DC Forward Current Gain HFE 200 650 1800 — V CE = 10 V, I B =20 µA 

Saturated DC Forward Current Gain HFE SAT 120 400 600 — V CE = 0.4 V, I B =20 µA 

Thermal Resistance, Junction to Lead R THJL — 500 — K/W — 

Package Transfer Characteristics (Each Channel) 

Parameter Symbol Min. Typ. Max. Unit Condition 

ILD/Q1 

Saturated Current Transfer Ratio (Collector-Emitter) CTR CESAT — 75 — % I F =10 mA, V CE =0.4 V 

Current Transfer Ratio (Collector-Emitter) CTR CE 20 80 300 % I F =10 mA, V CE =10 V 

ILD/Q2 



ILD/Q5 



Isolation and Insulation 

Common Mode Rejection, Output High C MH — 5000 — V/µs V CM =50 V P-P , R L =1.0 kΩ, I F =0 mA 

Common Mode Rejection, Output Low C ML — 5000 — V/µs V CM =50 V P-P , R L =1.0 kΩ, I F =10 mA 

Common Mode Coupling Capacitance C CM — 0.01 — pF — 

Package Capacitance C IO — 0.8 — pF V IO =0 V, f=1.0 MHz 




Typical Switching Times 

Figure 1. Non-saturated switching timing 

I F =10 mA 

F=10 KHz, 

DF=50% 

V CC =5 V 

V O 

R L =75 Ω 

Figure 2. Non-saturated switching timing 

I F 

Non-saturated 

Characteristic 

ILD/Q1 

I F =20 mA 

ILD/Q2 

I F =5.0 

mA 

ILD/Q5 

I F =10 

mA 

Delay, t D 0.8 1.7 1.7 µs 

Rise time, t r 1.9 2.6 2.6 µs 

Storage, t S 0.2 0.4 0.4 µs 

Fall Time, t f 1.4 2.2 2.2 µs 

Unit 

Propagation 0.7 1.2 1.1 µs 

H-L, t PHL 


L-H, t PLH 

Condition 

V CE =5.0 V 

R L =75 Ω 

50% of V PP 

V 0 

t PLH 

t PHL 

50% 

t F 

t D t R 

Figure 3. Saturated switching timing 

F=10 KHz, 

DF=50% 

I F =10 mA 

Figure 4. Saturated switching timing 

I F 

t S 

V CC =5 V 

R L 

V O 

Saturated 

Characteristic 

ILD/Q1 

I F =20 mA 

ILD/Q2 

I F =5.0 mA 

ILD/Q5 

I F =10 mA 

Delay, t D 0.8 1.0 1.7 µs 

Rise time, t r 1.2 2.0 7.0 µs 

Storage, t S 7.4 5.4 4.6 µs 

Fall Time, t f 7.6 13.5 20 µs 

Unit 


H-L, t PHL 


L-H, t PLH 

Figure 5. Normalized non-saturated and saturated 

CTR at T A =25°C versus LED current 

1.4 

V F - Forward Voltage - V 

1.3 

1.2 

1.1 

1.0 

0.9 

0.8 

T A = -55°C 

T A = 25°C 

T A = 100°C 

0.7 

.1 1 10 100 

I F - Forward Current - mA 

Condition 

V CE =0.4 V 

R L =1.0 kΩ 

V CC =5.0 V 

V TH =1.5 V 

t R 

V O 

t D 

t S 

t F 

t PHL 

t PLH 

V TH =1.5 V 



1.5 


V CE = 10 V, I F = 10 mA 

T A = 25°C 

1.0 CTRce(sat) V CE = 0.4 V 

CTRNF - Normalized CTR Factor 

0.5 

NCTR 

NCTR(SAT) 

0.0 

.1 1 10 100 

I F - LED Current - mA 






CTRNF - Normalized CTR Factor 

Figure 8. Normalized non-saturated and saturated CTR 

at T A =70°C versus LED current 

CTR - Normalized CTR Factor 

Figure 9. Normalized non-saturated and saturated CTR 

at T A =85°C versus LED current 

NCTR - Normalized CTR 

1.5 

1.0 

0.5 

0.0 

.1 1 10 100 


1.5 

1.0 

0.5 

0.0 

1.5 

1.0 

0.5 


V CE = 10 V, I F = 10 mA 

T A = 25°C 

CTRce(sat) V CE = 0.4 V 

T A = 50°C 

NCTR 

NCTR(SAT) 


V CE = 10 V, I F = 10 mA 

T A = 25°C 


T A = 70°C 

NCTR 

NCTR(SAT) 

.1 1 10 100 



V CE = 10 V, I F = 10 mA, T A = 25°C 


T A = 85°C 

NCTR 

NCTR(SAT) 

0.0 

.1 1 10 100 


Figure 10. Collector-emitter current versus temperature and 

LED current 

Ice - Collector Current - mA 

35 

30 

25 

20 

15 

10 

5 

0 

0 

25°C 

50°C 

85°C 

10 20 30 40 


Figure 11. Collector-emitter leakage current versus 

temperature 

I CEO - Collector-Emitter - nA 

10 5 

10 4 

10 3 

10 2 

10 1 

10 0 

10 -1 

Typical 

Figure 12. Propagation delay versus collector load 

resistor 

t pLH - Propagation Low-High - µs 

50 

70°C 

10 

-20 0 20 40 60 80 100 

-2 

T A - Ambient Temperature - °C 

1000 

100 

10 

T A = 25°C, I F = 10 mA 

V CC = 5 V, Vth = 1.5 V 

t pLH 

t pHL 

60 

V CE = 10 V 

2.5 

2.0 

1.5 

1 

1.0 

.1 1 10 100 

R L - Collector Load Resistor - KΩ 

t pHL - Propagation High-Low - µs

Optocoupler

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