L5973D - EBG - Darmstadt

■ 2.5A INTERNAL SWITCH
■ OPERATING INPUT VOLTAGE FROM 4.4V TO 36V
■ 3.3V / (±2%) REFERENCE VOLTAGE
■ OUTPUT VOLTAGE ADJUSTABLE FROM
1.235V TO 35V
■ LOW DROPOUT OPERATION: 100% DUTY
CYCLE
■ 250KHz INTERNALLY FIXED FREQUENCY
■ VOLTAGE FEEDFORWARD
■ ZERO LOAD CURRENT OPERATION
■ INTERNAL CURRENT LIMITING
■ INHIBIT FOR ZERO CURRENT
CONSUMPTION
■ SYNCHRONIZATION
■ PROTECTION AGAINST FEEDBACK
DISCONNECTION
■ THERMAL SHUTDOWN
APPLICATIONS:
■ CONSUMER: STB, DVD, TV, VCR,CAR
RADIO, LCD MONITORS
■ NETWORKING: XDSL, MODEMS,DC-DC
MODULES
■ COMPUTER: PRINTERS, AUDIO/GRAPHIC
CARDS, OPTICAL STORAGE, HARD DISK
DRIVE
■ INDUSTRIAL: CHARGERS, CAR BATTERY
DC-DC CONVERTERS
May 2003
HSOP8 - EXPOSED PAD
ORDERING NUMBER: L5973D
L5973D
2.5A SWITCH STEP DOWN SWITCHING REGULATOR
TEST APPLICATION CIRCUIT
VIN = 4.4V to 35V
C1
10μF
35V
CERAMIC
VREF
3.3V
C4
22nF
C3
220pF
VCC
SYNC.
COMP
R3
4.7K
6
8
2
4
INH
L5973D
3
DESCRIPTION
The L5973D is a step down monolithic power switching
regulator with a minimum switch current limit of
2.5A so it is able to deliver more than 2A DC current
to the load depending on the application conditions.
The output voltage can be set from 1.235V to 35V.
The high current level is also achieved thanks to an
SO8 package with exposed frame, that allows to reduce
the Rth(j-amb) down to approximately 40°C/W
The device uses an internal P-Channel D-MOS transistor
(with a typical Rdson of 250mΩ) as switching
element to minimize the size of the external components.
An internal oscillator fixes the switching frequency at
250KHz.
Having a minimum input voltage of 4.4V only, it is
particularly suitable for 5V bus, available in all computer
related applications.
Pulse by pulse current limit with the internal frequency
modulation offers an effective constant current
short circuit protection.
1
5
7
GND
OUT
FB
D03IN1439
L1 15μH
D1
STPS340U
R1
5.6K
R2
3.3K
VOUT=3.3V
C2
330μF
10V
1/10

L5973D
PIN CONNECTION
PIN DESCRIPTION
THERMAL DATA
(*) Package mounted on board
ABSOLUTE MAXIMUM RATINGS
2/10
N° Pin Function
1 OUT Regulator Output.
2 SYNC Master/slave synchronization.
3 INH A logical signal (active high) disables the device. If INH not used the pin must be grounded.
When it is open an internal pull-up disable the device.
4 COMP E/A output for frequency compensation.
5 FB Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external
resistive divider is required for higher output voltages.
6 VREF 3.3V VREF. No cap is requested for stability.
7 GND Ground.
8 VCC Unregulated DC input voltage.
Symbol Parameter Value Unit
Rth (j-amb) Thermal Resistance Junction to ambient Max. 40 (*) °C/W
Symbol Parameter Value Unit
V8 Input Voltage 40 V
V1
OUT
SYNC
INH
COMP
Output DC voltage
Output peak voltage at t = 0.1μs
1
2
3
4
D98IN955
-1 to 40
-5 to 40
I1 Maximum output current int. limit.
V4, V5 Analog pins 4 V
V3 INH -0.3V to VCC
V2 SYNC -0.3 to 4 V
Ptot Power dissipation at Tamb ≤ 60°C 2.25 W
Tj Operating junction temperature range -40 to 150 °C
Tstg Storage temperature range -55 to 150 °C
8
7
6
5
VCC
GND
VREF
FB
V
V

L5973D
ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 12V, unless otherwise specified.)
(*) Specification Referred to Tj from -40 to 125°C (1) .
Symbol Parameter Test Condition Min. Typ. Max. Unit
VCC Operating input voltage range Vo = 1.235V; Io = 2A * 4.4 36 V
RDSON Mosfet on Resistance * 0.150 0.5 Ω
Il Maximum limiting current VCC = 4.4V to 36V 2.5 3 3.5 A
fs Switching frequency * 212 250 280 KHz
225 250 275 KHz
Duty cycle 0 100 %
DYNAMIC CHARACTERISTICS (see test circuit ).
V5 Voltage feedback 4.4V < VCC < 36V,
1.220 1.235 1.25 V
20mA < IO < 2A
* 1.198 1.235 1.272 V
η Efficiency VO = 5V, VCC = 12V 90 %
DC CHARACTERISTICS
Iqop Total Operating Quiescent
Current
* 3 5 mA
Iq Quiescent current Duty Cycle = 0; VFB = 1.5V 2.5 mA
Iqst-by Total stand-by quiescent current Vinh > 2.2V * 50 100 μA
INHIBIT
VCC = 36V; Vinh > 2.2V * 80 150 μA
INH Threshold Voltage Device ON 0.8 V
Device OFF 2.2 V
ERROR AMPLIFIER
VOH High level output voltage VFB = 1V 3.5 V
VOL Low level output voltage VFB = 1.5V 0.4 V
Io source Source output current VCOMP = 1.9V; VFB = 1V 200 300 μA
Io sink Sink output current VCOMP = 1.9V; VFB = 1.5V 1 1.5 mA
Ib Source bias current 2.5 4 μA
DC open loop gain RL = ∞ 50 57 dB
gm Transconductance Icomp = -0.1mA to 0.1mA
VCOMP = 1.9V
2.3 mS
SYNC FUNCTION
High Input Voltage VCC = 4.4V to 36V 2.5 VREF V
Low Input Voltage VCC = 4.4V to 36V 0.74 V
Slave Sink Current Vsync = 0.74V
0.11
0.25 mA
Vsync = 2.33V
0.21
0.45 mA
Master Output Amplitude Isource = 3mA 2.75 3 V
Output Pulse Width
REFERENCE SECTION
no load, Vsync = 1.65V 0.20 0.35 μs
Reference Voltage 3.234 3.3 3.366 V
IREF = 0 to 5mA
VCC = 4.4V to 36V
* 3.2 3.3 3.399 V
Line Regulation IREF = 0mA
VCC = 4.4V to 36V
5 10 mV
Load Regulation IREF = 0 to 5mA 8 15 mV
Short Circuit Current 10 8 30 mA
Notes: 1. Specification over the -40 to +125 Tj Temperature range are assured by design, characterization and statistical correlation.
2. Guaranteed by design.
3/10

L5973D
Figure 1. Line Regulation
Vo (V)
3.312
3.308
3.304
3.3
3.296
3.292
3.288
3.284
3.28
3.276
Figure 2. Output Voltage vs. Junction
Temperature
Vo (V)
1.25
1.24
1.23
1.22
1.21
1.2
Figure 3. Quiescent Current vs. Junction
Temperature
4/10
Vcc = 12V
Vo = 3.3V
Tj = 25°C
Tj = 125°C
0 10 20 30 40
Vcc (V)
Vcc = 12V
Vcc=12V
-50 0 50
Tj (°C)
100 150
Iq (mA)
2
1.8
1.6
1.4
1.2
Vcc = 12V
DC = 0%
-50 0 50 100 150
Tj (°C)
Figure 4. Shutdown Current vs.Junction
Temperature
Ishd (μA)
70
60
50
40
30
Vcc = 12V
-50 0 50
Tj (°C)
100 150
Figure 5. Switching Frequency vs.Junction
Temperature
Fsw (KHz)
260
250
240
230
220
Vcc = 12V
Vo = 3.3V
-50 0 50 100 150
Tj (°C)

APPLICATION CIRCUIT
L5973D
In figure 6 is shown the demo board application circuit, where the input supply voltage, Vcc, can range from 4.4V
to 25V due to the rated voltage of the input capacitor and the output voltage is adjustable from 1.235V to Vcc.
Figure 6. Demo board Application Circuit
VIN = 4.4V to 25V
C1
10μF
25V
CERAMIC
Table 1. Component List
3.3V
C4
22nF
C3
220pF
VREF
VCC
SYNC.
COMP
R3
4.7K
6
8
2
4
INH
L5973D
3
D03IN1440
Reference Part Number Description Manufacturer
C1 10μF, 25V TOKIN
C2 POSCAP 6TPB330M 330μF, 6.3V Sanyo
C3 C1206C221J5GAC 220pF, 5%, 50V KEMET
C4 C1206C223K5RAC 22nF, 10%, 50V KEMET
R1 5.6K, 1%, 0.1W 0603 Neohm
R2 3.3K, 1%, 0.1W 0603 Neohm
R3 4.7K, 1%, 0.1W 0603 Neohm
D1 STPS2L25U 2A, 25V ST
L1 DO3316P-153 15μH, 3A COILCRAFT
7
GND
1
5
OUT
FB
L1 15μH
D1
STPS2L25U
R1
5.6K
R2
3.3K
VOUT=3.3V
C2
330μF
6.3V
5/10

L5973D
Figure 7. PCB layout (component side)
Figure 8. PCB layout (bottom side)
Figure 9. PCB layout (front side)
Below some graphs show the Tj versus output current in different conditions of the input and output voltage and
some efficiency measurements.
6/10
42mm
34mm

Figure 10. Junction Temperature vs. Output
Current (VCC = 5V)
Tj(°C)
120
110
100
90
80
70
60
50
40
30
20
Vin=5V
Tamb=25°C
Vo=3.3V
Vo=2.5V
Vo=1.8V
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Io(A)
2 2.2 2.4 2.6
Figure 11. Junction Temperature vs. Output
Current (VCC = 12V)
Tj (°C)
120
110
100
90
80
70
60
50
40
30
20
Vin=12V
Tamb=25°C
Vo=5V
Vo=3.3V
Vo=2.5V
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6
Io (A)
Figure 12. Efficiency vs. Output Current
(VCC = 5V)
Efficiency (%)
95
93
91
89
87
85
83
81
79
77
75
73
71
69
67
Vcc=5V
Vo=2.5V
Vo=1.8V
Vo=3.3V
Figure 13. Efficiency vs. Output Current
(VCC = 12V)
Efficiency (%)
91
89
87
85
83
81
79
77
75
L5973D
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
Io (A)
Vo=5V
Vo=3.3V
Vo=2.5V
73
71
69
67
Vcc=12V
65
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3
Io (A)
7/10

L5973D
APPLICATION IDEAS
Figure 14. Positive Buck-Boost regulator
VIN=5V
C1
10uF
10V
Ceramic
Figure 15. Buck-Boost regulator
Figure 16. Dual output voltage with auxiliary winding
8/10
VIN=5V
C1
10uF
10V
Ceramic
VIN=12V
C1
10uF
25V
Ceramic
C2
220pF
C3
22nF
R3
4.7k
C2
10uF
25V
Ceramic
C2
220pF
Vcc
COMP
C3
220pF
C3
22nF
R3
4.7k
8
4
2
SYNC VREF
VCC
COMP
C4
22nF
R3
4.7k
8
L5973D
6
3.3V
Vcc
COMP
4
2
SYNC VREF
GND
8
7
4
2
1
5
3
SYNC VREF
L5973D
6
3.3V
GND
7
INH
OUT
FB
L5973D
6
3.3V
GND
1
5
3
INH
D1
STPS2L25U
7
OUT
FB
1
5
3
INH
OUT
FB
L1
15uH
2.7k
24k
N1/N2=2
D1
STPS25L25U
M1
STN4NE03L
D1
STPS2L25U
C5
100uF
16V
D2
1N4148
Lp=22uH
D2
STPS2L25U
L1
15uH
24k
2.7k
C4
100uF
10V
VOUT=12V/0.6A
C4
100uF
16V
VOUT=-12V/0.6A
VOUT1=5V
50mA
VOUT=3.3V
0.5A
C5
47uF
10V

DIM.
mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A 1.350 1.750 0.531 0.069
A1
A2
B
C
D
E
e
H
h
L
0.100 0.250 0.004 0.010
1.100 1.650 0.043 0.065
0.330 0.510 0.013 0.020
0.190 0.250 0.07 0.010
4.800 5.000 0.189 0.197
3.800 4.000 0.150 0.157
1.270 0.05
5.800 6.200 0.228 0.244
0.250 0.500 0.010 0.020
0.400 1.270 0.016 0.05
k 0˚ (min), 8˚ (max)
ddd 0.100 0.010
(1) Dimension D does not include mold flash, protusions
or gate burrs shall not exeed 0.15mm (both side).
Exposed Pad:
D1 = 3.1mm
E1 = 2.41mm
OUTLINE AND
MECHANICAL DATA
HSOP8
(Exposed Pad)
L5973D
7195016
9/10

L5973D
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by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
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