DRV10987 Datasheet, PDF (12/69 Pages) Texas Instruments – DRV10987 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10987
SLVSE89 – AUGUST 2017
Feature Description (continued)
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IC
5V
V_CC VREG
47 µH
SW
10 µF
SWGND
Load
IC
5V
V_CC VREG
39 Ω
SW
10 µF
SWGND
Buck Regulator With External Inductor
Buck Regulator With External Resistor
Figure 3. Step-Down Regulator Configurations
8.3.1.2 3.3-V and 1.8-V LDOs
The DRV10987 device includes a 3.3-V LDO and a 1.8-V LDO. The 1.8-V LDO is for internal circuits only. The
3.3-V LDO is mainly for internal circuits, but can also drive external loads not to exceed I_{V3P3_MAX}. For example, it
can work as a pullup voltage for the FG, DIR, SDA, and SCL interfaces.
Both the V1P8 and V3P3 capacitors must be connected to GND.
8.3.2 Protection Circuits
8.3.2.1 Thermal Shutdown
The DRV10987 device has a built-in thermal shutdown function, which shuts down the device when the junction
temperature is more than T_SDN˚C and recovers operating conditions when the junction temperature falls to T_SDN –
T_{SDN_HYS}˚C.
The OverTemp status bit (address 0x00, bit 15) is set during thermal shutdown. In addition to the thermal
shutdown function, there is a warning bit that is set whenever the device exceeds T_WARN and is indicated by the
TempWarning bit of the FaultReg register (address 0x00, bit 14).
8.3.2.2 UVLO
The DRV10987 device has a built-in UVLO function block. The device is locked out when V_CC is below V_{UVLO_F}
and is unlocked when V_CC is above V_{UVLO_R}. The hysteresis of the UVLO threshold is V_{UVLO_HYS}. In addition to
the main supply, the step-down regulator, charge pump, and 3.3-V LDO all have undervoltage lockout monitors.
8.3.2.3 Current Protection
The overcurrent shutdown function acts to protect the device if the current, as measured from the FETs, exceeds
the I_OC-limit threshold. The overcurrent shutdown function protects the device in the event of a short-circuit
condition on the motor phases. A short-circuit condition includes phase shorts to GND, phase shorts to phase, or
phase shorts to V_CC. The DRV10987 device places the output drivers into a high-impedance state until the lock
time t_{LOCK_OFF} has expired. The OverCurr status bit of the FaultReg register (address 0x00, bit 11) is set.
The DRV10987 device also provides acceleration current-limit and lock-detection current-limit functions to protect
the device and motor (see Current Limit and Lock Detect and Fault Handling ).
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