m51996ap Renesas Electronics Corporation., m51996ap Datasheet - Page 18

• Manufacturer Part Number: m51996ap
• Description: Switching Regulator Control
• Manufacturer: Renesas Electronics Corporation.

M51996AP/AFP
When the current-limit signal is applied before the crossing instant of “A” pint potential and CF terminal voltage shown
in figure 7, this signal makes the output “off” and the off state will continue until next cycle. Figure 9 shows the timing
relation among them.
If the current limiting circuit is set, no waveform is generated at output terminal, however this state is reset during the
succeeding dead-time.
So this current limiting circuit is able to have the function in every cycle, and is named “pulse-by-pulse current limit”.
There happen some noise voltage on R
capacitor of the transformer windings.
To eliminate the abnormal operation by the noise voltage, the low pass filter, which consists of R
shown in figure 10.
It is recommended to use 10 to 100
some 200 A from CLM terminal and C
REJ03D0836-0201 Rev.2.01 Nov 14, 2007
Page 18 of 35
Figure 9 Operating Waveform of Current Limiting Circuit
Figure 10 Connection Diagram of Current Limit Circuit
Current limit signal
OSC waveform of
CLM+ terminal
V
Waveform of
Waveform of
OUT
CF terminal
to set latch
for R
CLM
terminal
NF
during the switching of power transistor due to the snubber circuit and stray
M51996A
NF
CLM+
is designed to have the enough value to absorb the noise voltage.
V
GND
because such range of R
OUT
Point D
V
C
THCLM
R
NF
NF
≈ 200 mV
NF
R
is not influenced by the flow-out current of
CLM+
NF
and C
NF
is used as