SN75372D datasheet(7/11 Pages) TI

7 / 11 page

SN75372

DUAL MOSFET DRIVER

SLLS025A – JULY 1986

3–7

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

THERMAL INFORMATION

power dissipation precautions

Significant power may be dissipated in the SN75372 driver when charging and discharging high-capacitance

loads over a wide voltage range at high frequencies. Figure 5 shows the power dissipated in a typical SN75372

as a function of load capacitance and frequency. Average power dissipated by this driver is derived from the

equation

PT(AV) = PDC(AV) + PC(AV) = PS(AV)

where PDC(AV) is the steady-state power dissipation with the output high or low, PC(AV) is the power level during

charging or discharging of the load capacitance, and PS(AV) is the power dissipation during switching between

the low and high levels. None of these include energy transferred to the load, and all are averaged over a full

cycle.

The power components per driver channel are

C(AV) [

CV2

tHL

tLH

T = 1/f

Figure 12. Output Voltage Waveform

where the times are as defined in Figure 14.

PDC(AV) =

PH t H + PL t L

PS(AV) =

PLH t LH + PHL t HL

PL, PH, PLH, and PHL are the respective instantaneous levels of power dissipation, C is the load capacitance.

VC is the voltage across the load capacitance during the charge cycle shown by the equation

VC = VOH – VOL

PS(AV) may be ignored for power calculations at low frequencies.

In the following power calculation, both channels are operating under identical conditions:

VOH =19.2 V and VOL = 0.15 V with VCC1 = 5 V, VCC2 = 20 V, VC = 19.05 V, C = 1000 pF, and the

duty cycle = 60%. At 0.5 MHz, PS(AV) is negligible and can be ignored. When the output voltage is high, ICC2

is negligible and can be ignored.

On a per-channel basis using data sheet values,

DC(AV) +

(5 V)

2mA

) (20 V) 0mA

(0.6)

) (5 V) 16 mA

) (20 V) 7mA

(0.4)

PDC(AV) = 47 mW per channel

Power during the charging time of the load capacitance is

PC(AV) = (1000 pF) (19.05 V)2 (0.5 MHz) = 182 mW per channel

Total power for each driver is

PT(AV) = 47 mW + 182 mW = 229 mW

and total package power is

PT(AV) = (229) (2) = 458 mW.

SN75372D Datasheet(PDF) 7 Page - Texas Instruments

SN75372D Datasheet(HTML) 7 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11

Datasheet Download

Link URL