H-Bridge and Dual Half Bridge Driver IC

TLE7181EM

Data Sheet

18

Rev 1.1, 2010-09-30

5.2.2

Short Circuit Protection

The TLE7181EM provides a short circuit protection for the external MOSFETs by monitoring the drain-source

voltage of the external MOSFETs.

This monitoring of the short circuit detection for a certain external MOSFET is active as soon as the corresponding

driver output stage is set to “on” and the dead time and the blanking time are expired.

The blanking time starts when the dead time has expired and assures that the switch on process of the MOSFET

is not taken into account. It is recommended to keep the switching times of the MOSFETs below the blanking time.

The short circuit detection level is adjustable in an analog way by the voltage setting at the SCDL pin. There is a

1:1 translation between the voltage applied to the SCDL pin and the drain-source voltage limit. E.g. to trigger the

SCD circuit at 1 V drain-source voltage, the SCDL pin must be set to 1 V. The drain-source voltage limit can be

chosen between 0.2 ... 2 V.

If after the expiration of the blanking time the drain source voltage of the observed MOSFET is still higher then the

SCDL level, the SCD filter time

t

reaches a specific level (filter time

t

condition is removed before the SC is detected, the capacitor is discharged with the same current. The discharging

of the capacitor happens as well when the MOSFET is switched off. It has to be considered that the high side and

the low side output of one phase are working with the same capacitor.

5.2.3

SCDL Pin Open Detection

An integrated structure at the SCDL pin assures that in case of an open pin the SCDL voltage is pulled to a medium

voltage level. The external MOSFETs are actively switched off and an ERR flag is set. This error is self-clearing.

5.2.4

Vs and VDH Over Voltage Warning

The TLE7181EM has an integrated over voltage warning to minimize risk of destruction of the IC at high supply

voltages caused by violation of the maximum ratings. For the over voltage warning the voltage is observed at the

pin VS and VDH. If the voltage level has reached, the fixed over voltage threshold

V

warning at ERR pin is set and TLE7181EM will go in normal operation with warning.

The over voltage warning is self clearing. If the voltage at pin VS and VDH returns into the specified voltage range,

the Error register will be cleared and TLE7181EM returns to normal operation mode.

It is the decision of the user, if and how to react on the over voltage warning.

5.2.5

VS Under Voltage Shutdown

The TLE7181EM has an integrated VS Under Voltage Shutdown, to assure that the behavior of the complete IC

is predictable in all supply voltage ranges. As soon as the under voltage threshold

V

filter time the TLE7181EM is in VS_UVLO error mode. The error signal will be set and output stages, voltage

regulator and charge pump will be switched off so the IC will go into sleep mode. An enable is necessary to restart

the TLE7181EM.

5.2.6

VREG Under Voltage Warning

The TLE7181EM has an integrated under voltage warning detection at VREG. If the supply voltage at VREG

reaches the VREG under voltage threshold

V

VREG error mode. In case of VREG error mode all output stages will actively switched off to prevent low gate

source voltages at the power MOSFETs causing high RDSon. If supply voltage at the VREG pin recovers; the

error flag will be cleared and the TLE7181EM will return in normal operation mode.