ICE3BR1765JZ
Functional Description
3.7.3.2
Auto Restart without extended blanking a trigger signal to the base of the externally added
time
transistor, TAE at the BA pin. When the function is
enabled, the gate drive switching will be stopped and
then the IC will enter auto-restart mode if the signal
persists. To ensure this auto-restart function will not be
mis-triggered during start up, a 1ms delay time is
implemented to blank the unstable signal.
VCC undervoltage is the Vcc voltage drop below Vcc
turn off threshold. Then the IC will turn off and the start
up cell will turn on automatically. And this leads to Auto
Restart Mode.
Auto Restart
Mode Reset
V
VCC < 10.5V
1ms
UVLO
counter
Auto-restart BA
Stop
gate
drive
Enable
Signal
8us
Blanking
Time
C9
C2
0.3V
25.5V
VCC
Auto Restart
mode
Short Optocoupler also leads to VCC undervoltage as
there is no self supply after activating the internal
reference and bias.
TAE
120us
Blanking
Time
Spike
VCC
&
Blanking
C1
C4
20.5V
30us
G1
softs_period
4.0V
Voltage
FB
Thermal Shutdown
Reference
T >140°C
j
Control Unit
Figure 26
Auto Restart mode
There are 2 modes of VCC overvoltage protection; one
is during soft start and the other is at all conditions.
The first one is VVCC voltage is > 20.5V and FB is > 4.0V
and during soft_start period and the IC enters Auto
Restart Mode. The VCC voltage is observed by
comparator C1 and C4. The fault conditions are to
detect the abnormal operating during start up such as
open loop during light load start up, etc. The logic can
eliminate the possible of entering Auto Restart mode if
there is a small voltage overshoots of VVCC during
normal operating.
The 2nd one is VVCC >25.5V and last for 120us and the
IC enters Auto Restart Mode. This 25.5V Vcc OVP
protection is inactivated during burst mode.
The Thermal Shutdown block monitors the junction
temperature of the IC. After detecting a junction
temperature higher than 130°C, the Auto Restart Mode
is entered.
In case the pre-defined auto-restart features are not
sufficient, there is a customer defined external Auto-
restart Enable feature. This function can be triggered
by pulling down the BA pin to < 0.33V. It can simply add
Version 2.0
18
12 Nov 2009
INFINEON [ Infineon ]
