STDRIVE102BH datasheet(36/56 Pages) STMICROELECTRONICS

36 / 56 page

Referring to Table 16, the state of the functional blocks can assume three different conditions:

•

Active: the block is fully operative.

•

LOW (gate drivers only): despite the digital inputs, the drivers are set LOW and they sink current.

Therefore, the external power MOSFET is turned off regardless of the digital input applied.

•

Disable: the functional block is disabled.

5.6.1

Automatic re-arm using the nFAULT pin

The VDS monitoring protection and the AFE comparators protection are latched: in case one of these protections

is triggered, the device latches and it cannot operate until the FAULT condition is released.

The release condition can be forced by applying a low pulse on the EN pin. Otherwise, the latch can be released

automatically, connecting together the EN and the nFAULT pins as shown in Figure 26.

Figure 26. Automatic re-arm using EN and nFAULT pins

nFAULT

GPIO

MCU

STDRIVE102

configuration

open drain

delay introduce by CENREN

time constant

EN/nFAULT

Drivers

Protection is triggered

Latch event

Gate Drivers Active

Gate Drivers LOW

Automatic re-arm

Vrelease

VIH

tdelay,EN

VDD

REN

CEN

When a protection is triggered, the nFAULT open-drain drives low the EN pin and its voltage falls below the

Vrelease threshold: the latch is then released. To avoid an immediate re-arm of the power stage, a delay can be

introduced using a capacitor CEN together with the pull-up resistor REN. The time required to reach the digital

threshold VIH increases, due to the smooth rising slope of the EN pin, thus delaying the re-arm of the drivers.

If a microcontroller is also connected to the EN pin, care must be taken to use an open-drain configuration for the

GPIO to avoid any conflict.

It is important to consider that the EN pin has an internal pull-down resistor RPD,EN so the voltage of the EN pin at

the end of the rising transient is:

Equation 5

VEN,ℎigℎ=VDD∙ RPD,EN

RPD,EN+REN

(5)

STDRIVE102BH, STDRIVE102H

Device description

DS14545 - Rev 1

page 36/56

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