TLE6711_07 Datasheet, PDF (12/25 Pages) Infineon Technologies AG – Multifunctional Voltage Regulator and Watchdog

TLE 6711
Circuit Description
The TLE 6711 G/GL is also protected against several boost loop errors:
In case of a feedback interruption a pull-up current source (I_FB typ. 0.4 µA), integrated at pin BOFB pulls the
voltage at the feedback pin BOFB above the reference voltage. The boost output is switched off by the high error
voltage which controls the PWM-Comparator at a zero duty cycle.
In the case of a resistive loop error caused by leakage currents to ground, the boost output voltage would increase
to very high values. In order to protect the V_BOOST input as well as the external load against catastrophic failures,
an overvoltage protection is provided which switches the output transistor off as soon as the voltage at pin V_BOOST
exceeds the internal fixed overvoltage threshold V_BOOVOFF = typ. 37 V.
Application Note
A short circuit from V_BOOST to ground will not destroy the IC, however, it may damage the external boost diode or
the boost inductance if there is no overcurrent limitation in that path.
V_C
and
V_Error
V_CP
Error Voltage
V_CV
OCLK
t
H
L
PWM
t
H
L
I _BOI
t
I _BOLI
I _DBO
t
V_BOI
t
V_BOOST
V_S
t
Overcurrent Threshold Exceeded
Load-Current Increasing with Time;
Controlled by the Error Amp
Controlled by the
Overcurrent Comp
AED02672
Figure 9 Most Important Waveforms of the Boost Converter Circuit
Data Sheet
12
Rev. 3.4, 2007-08-16