DRV8848_16 Datasheet, PDF (11/27 Pages) Texas Instruments – Dual H-Bridge Motor Driver

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DRV8848
SLLSEL7A – OCTOBER 2014 – REVISED NOVEMBER 2015
7.3.3 Parallel Operation
The two drivers can be used in parallel to deliver twice the current to a single motor. To enter parallel mode,
AIN1 and AIN2 must be left Hi-Z during power-up or when exiting sleep mode (nSLEEP toggling from 0 to 1).
BIN1 and BIN2 are used to control the drivers. Tie AISEN and BISEN to a single sense resistor if current control
is desired. To exit parallel mode, AIN1 and AIN2 must be driven high or low and the device must be powered-up
or exit sleep mode. Figure 7 shows a block diagram of the device using parallel mode.
VM
AIN1
AIN2
BIN1
Controller
BIN2
nSLEEP
Gate
Drive
and
VM
OCP
Logic
ISEN
VM
Gate
Drive
and
VM
OCP
AOUT1
AOUT2
AISEN
BOUT1
BOUT2
DCM
ISEN
VREF
Figure 7. Parallel Mode Operation
BISEN
optional
7.3.4 Current Regulation
The current through the motor windings is regulated by a fixed-off-time PWM current regulation circuit. With DC
brushed motors, current regulation can be used to limit the stall current (which is also the startup current) of the
motor.
Current regulation works as follows:
When an H-bridge is enabled, current rises through the winding at a rate dependent on the supply voltage and
inductance of the winding. If the current reaches the current chopping threshold, the bridge disables the current
for a time t_OFF before starting the next PWM cycle. Note that immediately after the current is enabled, the voltage
on the xISEN pin is ignored for a period of time (t_BLANK) before enabling the current sense circuitry. This blanking
time also sets the minimum on-time of the PWM cycle.
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