DRV8307_15 Datasheet, PDF (17/34 Pages) Texas Instruments – DRV8307 Brushless DC Motor Controller

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DRV8307
SLVSCK2 – APRIL 2014
VM
0.1 µF
35 V
0.1 µF
35 V
VM
CP1
CP2
Charge
Pump
VCP
1 µF
10 V
To Pre-Drivers
Figure 9. Charge Pump Block Diagram
8.3.9 5-V Linear Regulator
A 5-V linear regulator (VREG) is provided to power internal logic and external circuitry, such as the Hall effect
sensors.
A capacitor must be connected from the VREG output to ground, even if the output is not used for external
circuitry. The recommended capacitor value is a 0.1-μF, 10-V ceramic capacitor.
The VREG output is designed to provide up to 30-mA output current, but power dissipation and thermal
conditions must be considered. As an example, with 24 V in and 20 mA out, power dissipated in the linear
regulator is 19 V × 20 mA = 380 mW.
The VREG regulator is shutdown in standby mode (when ENABLEn is inactive).
8.3.10 Power Switch
A low-current switch is provided in the DRV8307 device that can be used to power the Hall sensors or other
external circuitry through the VSW terminal. When ENABLEn is active the switch is turned on, connecting the
VSW terminal to VM. When ENABLEn is inactive the switch is turned off (standby mode).
8.3.11 Protection Circuits
A number of protection circuits are included in the DRV8307 device. Faults are reported by asserting the
FAULTn terminal (an active-low, open-drain output signal).
8.3.11.1 VM Undervoltage Lockout (UVLO)
If the VM power supply drops, there may not be enough voltage to fully turn on the output FETs. Operation in this
condition causes excessive heating in the output FETs. To protect against this, the DRV8307 device contains an
UVLO circuit.
In the event that the VM supply voltage drops below the UVLO threshold (V_UVLO), the FAULTn terminal is driven
active and the motor driver is disabled. After VM returns to a voltage above the UVLO threshold, the FAULTn
terminal is high impedance and operation of the motor driver automatically resumes.
8.3.11.2 VM Overvoltage (VMOV)
In some cases, energy from the mechanical system can be forced back into the VM power supply. This can
result in the VM power supply being boosted by the energy in the mechanical system, causing breakdown of the
output FETs, or damaging the DRV8307 device. To protect against this, the DRV8307 device has overvoltage
protection.
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