PGND1

PGND2

PGND3

COMPP

COMPO

COMPN

Current Limit

R

SENSE

V

REF

V3P3OUT

B0482-01

–

DRV8313

SLVSBA5A – OCTOBER 2012 – REVISED NOVEMBER 2012

www.ti.com

Comparator

The DRV8313 includes an uncommitted comparator, which can find use as a current-limit comparator or for other

purposes.

The following diagram shows connections to use the comparator to sense current for implementing a current

limit. Current from all three low-side FETs is sensed using a single low-side sense resistor. The voltage across

the sense resistor is compared with a reference, and when the sensed voltage exceeds the reference, a current-

limit condition is signaled to the controller. The V3P3OUT internal voltage regulator can be used to set the

reference voltage of the comparator.

Figure 3. DRV8313 Comparator

nRESET and nSLEEP Operation

The nRESET pin, when driven active-low, resets any faults. It also disables the output drivers while it is active.

The device ignores all inputs while nRESET is active. Note that there is an internal power-up-reset circuit, so that

driving nRESET at power up is not required.

Driving nSLEEP low puts the device into a low-power sleep state. Entering this state disables the output drivers,

stops the gate-drive charge pump, resets all internal logic (including faults), and stops all internal clocks. In this

state, the device ignores all inputs until nSLEEP returns inactive-high. When returning from sleep mode, some

time (approximately 1 ms) must pass before the motor driver becomes fully operational. Note that the V3P3

regulator remains operational in sleep mode.

Protection Circuits

The DRV8313 has full protection against undervoltage, overcurrent, and overtemperature events.

OVERCURRENT PROTECTION (OCP)

An analog current-limit circuit on each FET limits the current through the FET by removing the gate drive. If

this analog current limit persists for longer than the OCP deglitch time, the device disables the channel

experiencing the overcurrent and drives the nFAULT pin low. The driver remains off until either assertion of

nRESET or the cycling of VM power.

Overcurrent conditions on both high- and low-side devices, that is, a short to ground, supply, or across the

motor winding, all result in an overcurrent shutdown.

THERMAL SHUTDOWN (TSD)

If the die temperature exceeds safe limits, the device disables all outputs and drives the nFAULT pin low.

Once the die temperature has fallen to a safe level, operation automatically resumes.

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