VNH3SP30 datasheet(8/26 Pages) STMICROELECTRONICS

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VNH3SP30

REVERSE BATTERY PROTECTION

Three possible solutions can be thought of:

a) a Schottky diode D connected to VCC pin

b) a N-channel MOSFET connected to the GND pin (see Typical Application Circuit on page 7)

c) a P-channel MOSFET connected to the VCC pin

The device sustains no more than -30A in reverse battery conditions because of the two Body diodes of

the Power MOSFETs. Additionally, in reverse battery condition the I/Os of VNH2SP30 will be pulled down

to the VCC line (approximately -1.5V). Series resistor must be inserted to limit the current sunk from the

microcontroller I/Os. If IRmax is the maximum target reverse current through µC I/Os, series resistor is:

OPEN LOAD DETECTION IN OFF-MODE

It is possible for the microcontroller to detect an open load condition by adding a simply resistor (for

example 10k

Ω) between one of the outputs of the bridge (for example OUT

B) and one microcontroller

input. A possible sequence of inputs and enable signals is the following: INA=1, INB=X, ENA= 1, ENB=0.

normal condition: OUTA=H and OUTB=H

open load condition: OUTA=H and OUTB=L: in this case the OUTB pin is internally pulled down to

GND. This condition is detected on OUTB pin by the microcontroller as an open load fault.

SHORT CIRCUIT PROTECTION

In case of a fault condition the DIAGX/ENX pin is considered as an output pin by the device.

The fault conditions are:

- overtemperature on one or both high sides;

- short to battery condition on the output (saturation detection on the Low-Side Power MOSFET).

Possible origins of fault conditions may be:

OUTA is shorted to ground ---> overtemperature detection on high side A.

OUTA is shorted to VCC ---> Low-Side Power MOSFET saturation detection.

(1)

When a fault condition is detected, the user can know which power element is in fault by monitoring the

INA, INB, DIAGA/ENA and DIAGB/ENB pins.

In any case, when a fault is detected, the faulty half bridge is latched off. To turn-on the respective output

(OUTX) again, the input signal must rise from low to high level.

(1) An internal operational amplifier compares the Drain-Source MOSFET voltage with the internal reference (2.7V Typ.).

The relevant Lowside PowerMOS is switched off when its Drain-Source voltage exceeds the reference voltage.

TRUTH TABLE IN FAULT CONDITIONS (detected on OUTA)

INA

INB

DIAGA/ENA

DIAGB/ENB

OUTA

OUTB

OPEN

IO s

–

Rm ax

-------------------------------

Fault Information

Protection Action

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