TC4467/TC4468/TC4469 - Microchip

TC4467/TC4468/TC4469
A resistive-load-caused dissipation for supplyreferenced
loads is a function of duty cycle, load
current and output voltage. The power dissipation is
EQUATION
Quiescent power dissipation depends on input signal
duty cycle. Logic HIGH outputs result in a lower power
dissipation mode, with only 0.6 mA total current drain
(all devices driven). Logic LOW outputs raise the
current to 4 mA maximum. The quiescent power
dissipation is:
EQUATION
P L
= DVOIL D = Duty Cycle
VO = Device Output Voltage
IL = Load Current
P Q
= VS( DI ( H)
+ ( 1 – D)IL)
IH = Quiescent Current with all outputs LOW
(4 mA max.)
IL = Quiescent Current with all outputs HIGH
(0.6 mA max.)
D = Duty Cycle
VS = Supply Voltage
Transition power dissipation arises in the complimentary
configuration (TC446X) because the output stage
N-channel and P-channel MOS transistors are ON
simultaneously for a very short period when the output
changes. The transition power dissipation is
approximately:
1 µF Film 0.1 µF Ceramic
1A
1B
2A
2B
3A
3B
4A
4B
1
2
3
4
5
6
8
9
V DD
7
14
V OUT
470 pF
FIGURE 4-1: Switching Time Test Circuit.
13
12
11
10
+5 V
Input
(A, B)
0V
V DD
Output
0V
EQUATION
Package power dissipation is the sum of load,
quiescent and transition power dissipations. An
example shows the relative magnitude for each term:
Maximum operating temperature is:
EQUATION
PT fVs 10 10 9 –
= ( × )
C = 1000 pF Capacitive Load
VS = 15 V
D = 50%
f = 200 kHz
Note: Ambient operating temperature should not
exceed +85°C for "EJD" device or +125°C
for "MJD" device.
DS21425B-page 10 © 2002 Microchip Technology Inc.
10%
P D
= Package Power Dissipation
= PL + PQ + PT = 45mW + 35mW + 30mW
= 110mW
TJ – θJA( PD) = 141°C
TJ = Maximum allowable junction temperature
(+150°C )
θJA = Junction-to-ambient thernal resistance
(83.3°C/W) 14-pin plastic package
Input: 100 kHz,
square wave,
t RISE = t FALL ≤ 10 nsec
90%
tD1 t R
90%
t D2
10% 10%
90%
t F