Data Sheet

17

Rev. 1.0, 2010-05-28

High Current H-Bridge

BTM7745G

Block Description and Characteristics

6.4

Control and Diagnostics

6.4.1

Input Circuit

The control inputs INx and INH consist of TTL/CMOS compatible schmitt triggers with hysteresis which control the

integrated gate drivers for the MOSFETs. To set the device in stand-by mode, INH and INx pins need to be all

connected to GND. When the INH is high, in each half bridge one of the two power switches (HSx or LSx) is

switched on, while the other power switch is switched off, depending on the status of the INx pin. When INH is low,

a high INx signal will turn the corresponding highside switches on. This provides customer the possibility to switch

on one high side switch while keeping the other switches off and therefore to do an open load detection together

with external circuitry (see also Chapter 7 - Application Information). A low on all INx and INH signal will turn off

both power switches. To drive the logic inputs no external driver is needed, therefore the BTM7745G can be

interfaced directly to a microcontroller.

6.4.2

Dead Time Generation

In bridge applications it has to be assured that the highside and lowside MOSFET are not conducting at the same

time, connecting directly the battery voltage to GND. This is assured by a circuit in the driver IC, which senses the

status of the MOSFETs to ensure that the high or low side switch can be switched on only if the corresponding

low or high side switch is completely turned off.

6.4.3

Status Flag Diagnosis

The status pin provides diagnostic signal of the device. It is an open drain output which requires a pull-up resistor.

In case of overvoltage, overtemperature and overcurrent situation the status output is switched to low. In case of

current limitation the status output is activated for 1.5 *

t