Datasheet

PWM OP
0.6V
10kΩ
Oscillator
C8
T
2
R
1
C
1
FB
PWM-Latch
V
1
Gate Driver
Voltage Ramp
V
OSC
Soft-Start Comparator
time delay
circuit (156ns)
X3.2
PWM Comparator
CoolSET
®
-F3
ICE3A1065ELJ
Functional Description
Version 2.3 10 19 Nov 2012
Figure 6 Improved Current Mode
t
t
V
OSC
0.6V
FB
t
max.
Duty Cycle
Gate Driver
Voltage Ramp
156ns time delay
Figure 7 Light Load Conditions
3.3.1 PWM-OP
The input of the PWM-OP is applied over the internal
leading edge blanking to the external sense resistor
R
Sense
connected to pin CS. R
Sense
converts the source
current into a sense voltage. The sense voltage is
amplified with a gain of 3.2 by PWM OP. The output of
the PWM-OP is connected to the voltage source V
1
.
The voltage ramp with the superimposed amplified
current signal is fed into the positive inputs of the PWM-
Comparator C8 and the Soft-Start-Comparator (see
Figure 6).
3.3.2 PWM-Comparator
The PWM-Comparator compares the sensed current
signal of the integrated CoolMOS
®
with the feedback
signal V
FB
(see Figure 8). V
FB
is created by an external
optocoupler or external transistor in combination with
the internal pull-up resistor R
FB
and provides the load
information of the feedback circuitry. When the
amplified current signal of the integrated CoolMOS
®
exceeds the signal V
FB
the PWM-Comparator switches
off the Gate Driver.
X3.2
PWM OP
Improved
Current Mode
PWM Comparator
CS
Soft-Start Comparator
5V
C8
0.6V
FB
Optocoupler
R
FB
PWM-Latch
Figure 8 PWM Controlling