Datasheet

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SLRS028A − SEPTEMBER 1988 − REVISED NOVEMBER 2004
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THERMAL INFORMATION
power-dissipation precautions (continued)
P
L
, P
H
, P
LH
, and P
HL
are the respective instantaneous levels of power dissipation, and C is the load capacitance.
V
C
is the voltage across the load capacitance during the charge cycle shown by the equation:
V
C
= V
OH
− V
OL
P
S(AV)
may be ignored for power calculations at low frequencies.
In the following power calculation, all four channels are operating under identical conditions: f = 0.2 MHz,
V
OH
= 19.9 V and V
OL
= 0.15 V with V
CC1
= 5 V, V
CC2
= 20 V, V
CC3
= 24 V, V
C
= 19.75 V, C = 1000 pF, and the
duty cycle = 60%. At 0.2 MHz for C
L
< 2000 pF, P
S(AV)
is negligible and can be ignored. When the output voltage
is low, I
CC2
is negligible and can be ignored.
On a per-channel basis using data-sheet values,
P
DC(AV)
+
ƪ
5V
ǒ
4mA
4
Ǔ
) 20 V
ǒ
−2.2 mA
4
Ǔ
) 24 V
ǒ
2.2 mA
4
Ǔ
ƫ
0.6 )
ƪ
5V
ǒ
31 mA
4
Ǔ
) 20 V
ǒ
0mA
4
Ǔ
) 24 V
ǒ
16 mA
4
Ǔ
ƫ
0.4
P
DC(AV)
= 58.2 mW per channel
Power during the charging time of the load capacitance is
P
C(AV)
= (1000 pF)(19.75 V)
2
(0.2 MHz) = 78 mW per channel
Total power for each driver is:
P
T(AV)
= 58.2 mW + 78 mW = 136.2 mW
The total package power is:
P
T(AV)
= (136.2)(4) = 544.8 mW