DRV8412 Datasheet, PDF (13/28 Pages) Texas Instruments – Dual Full Bridge PWM Motor Driver

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DIFFERENT OPERATIONAL MODES
The DRV8412/22/32 support four different modes of
operation:
1. Dual full bridges (FB) (two PWM inputs each full
bridge) or four half bridges (HB) with CBC current
limit
2. Dual full bridges (two PWM inputs each full
bridge) or four half bridges with OC latching
shutdown (no CBC current limit)
3. Parallel full bridge (PFB) with CBC current limit
4. Dual full bridges (one PWM input each full bridge)
with CBC current limit
In mode 1 and 2, PWM_A controls half bridge A,
PWM_B controls half bridge B, etc. Figure 8 shows
an application example for full bridge mode operation.
In parallel full bridge mode (mode 3), PWM_A
controls both half bridges A and B, and PWM_B
controls both half bridges C and D, while PWM_C
and PWM_D pins are not used (recommended to
connect to ground). Bridges A and B are
synchronized internally (even during CBC), and so
are bridges C and D. OUT_A and OUT_B should be
connected together and OUT_C and OUT_D should
be connected together after the output inductor or
ferrite bead. Figure 9 shows an example of parallel
full bridge mode connection.
In mode 4, one PWM signal controls one full bridge to
relieve some I/O resource from MCU, i.e., PWM_A
controls half bridges A and B and PWM_C controls
DRV8412
DRV8422
DRV8432
SLES242A – DECEMBER 2009 – REVISED DECEMBER 2009
half bridges C and D. In this mode, the operation of
half bridge B is complementary to half bridge A, and
the operation of half bridge D is complementary to
half bridge C. For example, when PWM_A is high,
high side FET in half bridge A and low side FET in
half bridge B will be on and low side FET in half
bridge A and high side FET in half bridge B will be
off. Since PWM_B and PWM_D pins are not used in
this mode, it is recommended to connect them to
ground.
Because each half bridge has independent supply
and ground pins, a shunt sensing resistor can be
inserted between PVDD to PVDD_X or GND_X to
GND (ground plane). A high side shunt resistor
between PVDD and PVDD_X is recommended for
differential current sensing because a high bias
voltage on the low side sensing could affect device
operation. If low side sensing has to be used, a shunt
resistor value of 10 mΩ or less or sense voltage 100
mV or less is recommended.
The DRV8412/22/32 can be used for stepper motor
applications as illustrated in Figure 10; they can be
also used in three phase permanent magnet
synchronous motor (PMSM) and sinewave brushless
DC motor applications. Figure 11 and Figure 12 show
the three-phase application example with different
current sense locations.
Figure 13 shows an example of a TEC driver
application. Same configuration can also be used for
DC output applications.
During T_OC Period
PVDD
PWM_HS
Load
Current
CBC with High Side OC
Current Limit
Load
PWM_HS
PWM_LS
GND_X
PWM_LS
T_HS T_OC T_LS
Figure 6. Cycle-by-Cycle Operation with High Side OC (dashed line: normal operation; solid line: CBC
event)
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