DRV8801-Q1 Datasheet, PDF (14/23 Pages) Texas Instruments – DMOS FULL-BRIDGE MOTOR DRIVERS

DRV8800-Q1
DRV8801-Q1
SLVSAS7 – FEBRUARY 2011
APPLICATION INFORMATION
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Power Dissipation
First-order approximation of power dissipation in the DRV8800-Q1/DRV8801-Q1 can be calculated by examining
the power dissipation in the full-bridge during each of the operation modes. DRV8800-Q1/DRV8801-Q1 utilize
synchronous rectification. During the decay cycle, the body diode is shorted by the low-R_ds(ON) driver, which in
turn reduces power dissipation in the full-bridge. In order to prevent shoot through (high-side and low-side drivers
on the same side are ON at the same time), DRV8800-Q1/DRV8801-Q1 implement a 500-ns typical crossover
delay time. During this period, the body diode in the decay current path conducts the current until the DMOS
driver turns on. High current and high ambient temperature applications should take this into consideration. In
addition, motor parameters and switching losses can add power dissipation that could affect critical applications.
Drive Current
This current path is through the high-side sourcing DMOS driver, motor winding, and low-side sinking DMOS
driver. Power dissipation I2R loses in one source and one sink DMOS driver, as shown in Equation 1.
) P_D = I²(R_DS(on)Source + R_DS(onSink)
(1)
DRV8800-Q1
VBB
1
3
2
1 Drive Current
2 Fast decay with synchronous rectification (reverse)
3 Slow decay with synchronous rectification (brake)
14
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