DRV8830_16 Datasheet, PDF (20/22 Pages) Texas Instruments – Low-Voltage Motor Driver With Serial Interface

DRV8830
SLVSAB2G – MAY 2010 – REVISED DECEMBER 2015
10 Layout
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10.1 Layout Guidelines
The VCC pin should be bypassed to GND using low-ESR ceramic bypass capacitors with a recommended value
of 0.1-μF rated for VCC. This capacitor should be placed as close to the VCC pin as possible with a thick trace
or ground plane connection to the device GND pin.
The VCC pin must be bypassed to ground using an appropriate bulk capacitor. This component may be an
electrolytic and should be located close to the DRV8830.
10.2 Layout Example
10 µF
OUT2
ISENSE
OUT1
VCC
GND
SCL
SDA
A1
A0
FAULTn
Figure 18. Layout Recommendation
10.3 Thermal Considerations
The DRV8830 has thermal shutdown (TSD) as described in Thermal Shutdown (TSD). If the die temperature
exceeds approximately 160°C, the device will be disabled until the temperature drops to a safe level. Any
tendency of the device to enter TSD is an indication of either excessive power dissipation, insufficient
heatsinking, or too high an ambient temperature.
10.3.1 Power Dissipation
Power dissipation in the DRV8830 is dominated by the power dissipated in the output FET resistance, or R_DS(ON).
Average power dissipation when running a stepper motor can be roughly estimated by Equation 3.
P = 2 R (I )²
TOT
· _DS(ON) · _OUT(RMS)
(3)
where P_TOT is the total power dissipation, R_DS(ON) is the resistance of each FET, and I_OUT(RMS) is the RMS output
current being applied to each winding. I_OUT(RMS) is equal to the approximately 0.7x the full-scale output current
setting. The factor of 2 comes from the fact that at any instant two FETs are conducting winding current for each
winding (one high-side and one low-side).
The maximum amount of power that can be dissipated in the device is dependent on ambient temperature and
heatsinking.
Note that R_DS(ON) increases with temperature, so as the device heats, the power dissipation increases. This must
be taken into consideration when sizing the heatsink.
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