TLE7183F Datasheet, PDF (16/28 Pages) Infineon Technologies AG – 3-Phase Bridge Driver IC

TLE7183F
5.2
Protection and Diagnostic Functions
5.2.1 Short Circuit Protection
The TLE7183F provides a short circuit protection for the external MOSFETs. It is a monitoring of the drain-source
voltage of the external MOSFETs. As soon as this voltage is higher than the short circuit detection limit, a timer
will start to run.
The short circuit detection level is programmed fix in the chip. 5 different short circuit level options are available:
Table 2 Short circuit detection level options
TLE7183
SCD1
SCD2
SCD3
SCD4
SCD5
typ. short ciruit detection level
0.5V
0.75V
1.0V
1.5V
2.0V
After a delay of about 6 µs all external MOSFETs will be switched off until the driver is reset by the ENAx pin. The
error flag is set.
The drain-source voltage monitoring of the short circuit detection for a certain external MOSFET is active as soon
as the corresponding input is set to "on" and the dead time is expired.
5.2.2 Overcurrent Warning
The TLE7183F offers the possibility to shut down the output stages if a current threshold is reached. (see Figure 4
). The output of the current sense OpAmp is connected to an integrated comparator, comparing the amplified
current sense signal with an external adjustable threshold value. After the comparator a blanking time (1.5 µs typ.)
is implemented to avoid false triggering caused by overswing of the current sense signal.
If the overcurrent situation is detected, only an error signal is given. During overcurrent the driver IC works
normally. The error signal disappears as soon as the current decreases below the overcurrent limit set on the
VTHOC pin. The error signal disappears as well when the current commutates from the low side MOSFET to the
associated high side MOSFET (no current through the shunt resistor).
It is the decision of the user to react on the over current signal by modifying the Ixx patterns to lower the current.
5.2.3 Dead Time and Shoot Through Protection
In bridge applications it has to be assured that the external high side and low side Mosfet are not "on" at the same
time, connecting directly the battery voltage to GND. The dead time generated in the TLE7183F is fixed to a
minimum value of 50..200ns if the DT pin is connected to GND. This function assures a minimum dead time if the
input signals coming from the µC are faulty.
The dead time can be increased beyond the internal fixed dead time by connecting the DT pin via a dead time
resistor R_DT to GND - the larger the dead time resistor the larger the dead time (for details pls. see the “Dynamic
Characteristic” table in the MOSFET driver section).
The exact dead time of the bridge is usually controlled by the PWM generation unit of the µC.
In addition to this dead time, the TLE7183F provides a locking mechanism, avoiding that both external MOSFETs
of one half bridge can be switched on at the same time. This functionality is called shoot through protection.
If the command to switch on both high and low side switches in the same half bridge is given at the input pins, the
command will be ignored.
Data Sheet
16
V2.1, 2008-04-30