Data Sheet

11

Rev 1.1, 2010-09-30

H-Bridge and Dual Half Bridge Driver IC

TLE7181EM

Description and Electrical Characteristics

Figure 3

Block Diagram of Driver Stages including Short Circuit Detection

5.1.3

Dead Time

In bridge applications it has to be assured that the external high side and low side MOSFETs are not “on” at the

same time, connecting directly the battery voltage to GND. The dead time generated in the TLE7181EM can be

programmed by applying an resistor between the DT pin and GND. Higher external resistor values lead to higher

dead time.

A minimum dead time applied, if the DT pin is connected to GND.

The typical dead time can be calculated with the following formula:

If an exact dead time of the bridge is needed, the use of the µC PWM generation unit is recommended.

5.1.4

Bootstrap Principle

The TLE7181EM provides a bootstrap based supply for its high side output stages.

The bootstrap capacitors are charged by switching on the external low side MOSFETs, connecting the bootstrap

capacitor to GND. Under this condition the bootstrap capacitor will be charged from the VREG capacitor via the

integrated bootstrap diode. If the low side MOSFET is switched off and the high side MOSFET is switched on, the

bootstrap capacitor will float together with the SHx voltage to the supply voltage of the bridge. Under this condition

the supply current of the high side output stage will discharge the bootstrap capacitor. This current is specified.

The size of the capacitor together with this current will determine how long the high side MOSFET can be kept on

without recharging the bootstrap capacitor.

GHx

SHx

VDH

V

SCP

+

-

Level

shifter

Floating HS driver 2x

GLx

SL

+

-

Level

shifter

Floating LS driver 2x

VREG

Voltage regulator

BHx

VREG

ENA

VS

Error logic

Reset

Power On Reset

____

ERR

short circuit filter

SCD

SCD

SCD

Input Logic

Dead Time

lock /

unlock

PWM

DIR

ON / OFF

ON / OFF

GND

DT

Short Circuit

Detection Level

SCDL

VDH

VRE G

blanking

DRVDIS

Charge pump

RPP

]

[

4

4

.

2

02

.

0

081

.

0

]

[

Ω

+

+

=

k

Rdt

t