33981 datasheet(15/37 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33981

FUNCTIONAL DEVICE OPERATION

PROTECTION AND DIAGNOSTIC FEATURES

Figure 11. Reverse Battery Protection

GROUND (GND) DISCONNECT PROTECTION

If the DC motor module ground is disconnected from load

ground, the device protects itself and safely turns OFF the

output regardless of the output state at the time of

disconnection. A 10 k resistor needs to be added between

the EN pin and the rest of the circuitry in order to ensure the

device turns off in case of ground disconnect and to prevent

exceeding this pin’s maximum ratings.

FAULT REPORTING

This 33981 indicates the faults below as they occur by

driving the FS pin to logic [0]:

• Over-temperature fault

• Over-current fault on OUT

• Overload fault on the external low side MOSFET

The FS pin will return to logic [1] when the over

temperature fault condition is removed. The two other faults

are latched.

VPWR

VDD

VPWR

MCU

33981

No current

GND

OUT

Diode

10.0 k

Table 6. Functional Truth Table in Fault Mode

Conditions

CONF INHS

INLS

OUT

GLS

TEMP CSNS OCLS

Comments

Over-temperature

on OUT

The 33981 is currently in Fault Mode.

The OUT is OFF. TEMP at 0V indicates

this fault. Once the fault is removed

33981 recovers its normal mode.

Over-temperature

on GLS

The 33981 is currently in Fault Mode.

The OUT is OFF and GLS is at 0V.

TEMP at 0V indicates this fault. Once

the fault is removed 33981 recovers its

Normal Mode.

Over-current

on OUT

The 33981 is currently in Fault Mode.

The OUT is OFF. It is reset by a

logic [0] at INHS for at least

tRST(DIAG).

When INHS goes to 0V, CSNS goes to

5.0 V.

Overload

on External Low

Side MOSFET

The 33981 is currently in Fault Mode.

GLS is at 0 V and OCLS internal

current source is off. The external

resistance connected between OCLS

and GND pin will pull OCLS pin to 0V.

The fault is reset by a logic [0] at INLS

for at least

tRST(DIAG).

H = High level

L = Low level

x = Don’t care

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