Datasheet

PWM_HS
PWM_LS
Load
Current
CurrentLimit
T_HS
T_OC
PVDD
GND_X
PWM_HS
PWM_LS
Load
T_LS
CBCwithHighSideOC
DuringT_OCPeriod
DRV8412
DRV8432
www.ti.com SLES242C –DECEMBER 2009–REVISED MAY 2010
DIFFERENT OPERATIONAL MODES half bridges C and D. In this mode, the operation of
half bridge B is complementary to half bridge A, and
The DRV8412/32 support four different modes of
the operation of half bridge D is complementary to
operation:
half bridge C. For example, when PWM_A is high,
1. Dual full bridges (FB) (two PWM inputs each full
high side FET in half bridge A and low side FET in
bridge) or four half bridges (HB) with CBC current
half bridge B will be on and low side FET in half
limit
bridge A and high side FET in half bridge B will be
off. Since PWM_B and PWM_D pins are not used in
2. Dual full bridges (two PWM inputs each full
this mode, it is recommended to connect them to
bridge) or four half bridges with OC latching
ground.
shutdown (no CBC current limit)
3. Parallel full bridge (PFB) with CBC current limit
Because each half bridge has independent supply
and ground pins, a shunt sensing resistor can be
4. Dual full bridges (one PWM input each full bridge)
inserted between PVDD to PVDD_X or GND_X to
with CBC current limit
GND (ground plane). A high side shunt resistor
In mode 1 and 2, PWM_A controls half bridge A,
between PVDD and PVDD_X is recommended for
PWM_B controls half bridge B, etc. Figure 8 shows
differential current sensing because a high bias
an application example for full bridge mode operation.
voltage on the low side sensing could affect device
operation. If low side sensing has to be used, a shunt
In parallel full bridge mode (mode 3), PWM_A
resistor value of 10 mΩ or less or sense voltage 100
controls both half bridges A and B, and PWM_B
mV or less is recommended.
controls both half bridges C and D, while PWM_C
and PWM_D pins are not used (recommended to
The DRV8412/32 can be used for stepper motor
connect to ground). Bridges A and B are
applications as illustrated in Figure 10; they can be
synchronized internally (even during CBC), and so
also used in three phase permanent magnet
are bridges C and D. OUT_A and OUT_B should be
synchronous motor (PMSM) and sinewave brushless
connected together and OUT_C and OUT_D should
DC motor applications. Figure 11 and Figure 12 show
be connected together after the output inductor or
the three-phase application example with different
ferrite bead. Figure 9 shows an example of parallel
current sense locations.
full bridge mode connection.
Figure 13 shows an example of a TEC driver
In mode 4, one PWM signal controls one full bridge to
application. Same configuration can also be used for
relieve some I/O resource from MCU, i.e., PWM_A
DC output applications.
controls half bridges A and B and PWM_C controls
Figure 6. Cycle-by-Cycle Operation with High Side OC (dashed line: normal operation; solid line: CBC
event)
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