MP6531A – 5V - 60V, THREE-PHASE BLDC MOTOR PRE-DRIVER

MP6531A Rev. 1.02

www.MonolithicPower.com

12

6/20/2017

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Over-Current Protection (OCP)

The MP6531A can implement output over-

current protection (OCP) by monitoring the

current

through

a

low-side

shunt

resistor

connected to the LS-FETs. This resistor is

connected to the LSS input pin and the LS-FET

source terminals. If the OCP function is not

desired,

LSS

and

the

MOSFET

source

terminals should all be connected to ground

directly.

If the LSS voltage (the voltage across the shunt

resistor) exceeds the LSS OCP threshold

Once an OCP event is detected, the MP6531A

enters a latched fault state and disables all

functions. The device remains latched off until it

is reset by nSLEEP or VIN UVLO. The OCP

current limit level is selected by the value of the

current sense resistor at LSS.

OCP protection can be disabled by connection

a 100k

Ω resistor from VREG to the OCREF pin.

Short-Circuit and OCP Deglitch Time

There is often a current spike during switching

transitions caused by the body diode reverse-

recovery current or the distributed capacitance

of the load. This current spike requires filtering

to prevent it from erroneously triggering OCP.

output of the VDS monitor when the outputs are

switched.

Dead-Time Adjustment

To prevent shoot-through in any phase of the

bridge, it is necessary to have a dead time

the next complementary turn-on event. The

dead time for all three phases is set by a single

ground with Equation (1):

(1)

If DT is tied to ground directly, an internal

minimum dead time (130ns) is applied.

Under-Voltage Lockout (UVLO) Protection

If at any time the voltage on VIN falls below the

circuitry in the device is disabled, and the

internal logic is reset. Operation resumes with

the power-up sequence when VIN rises above

the UVLO thresholds.

After power-up, if the voltage on VREG drops

enters a latched fault state and disables all

functions. nFAULT is driven active low. The

device remains latched off until it is reset by

nSLEEP or VIN UVLO.

Thermal Shutdown

If the die temperature exceeds safe limits, the

MP6531A enters a latched fault state and

disables all functions. The device remains

latched off until it is reset by nSLEEP or VIN

UVLO.