DRV8800_12 Datasheet, PDF (14/27 Pages) Texas Instruments – DMOS FULL-BRIDGE MOTOR DRIVERS

DRV8800
DRV8801
SLVS855F – JULY 2008 – REVISED JANUARY 2012
APPLICATION INFORMATION
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Power Dissipation
First-order approximation of power dissipation in the DRV8800/DRV8801 can be calculated by examining the
power dissipation in the full-bridge during each of the operation modes. DRV8800/DRV8801 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/DRV8801 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
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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