M51995AFP#CF0J Renesas Electronics America, M51995AFP#CF0J Datasheet - Page 23

• Manufacturer Part Number: M51995AFP#CF0J
• Description: IC SWIT PWM SMPS OVP UVLO 20SOIC
• Manufacturer: Renesas Electronics America

Specifications of M51995AFP#CF0J

• Output Isolation: Isolated
• Frequency Range: 170 ~ 207kHz
• Voltage - Input: 9.9 ~ 36 V
• Power (watts): 1.5W
• Operating Temperature: -30°C ~ 85°C
• Package / Case: 20-SOIC (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

M51995AP/AFP
Current Limiting Section
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.
The current limiting circuit has two input terminals, one has the detector-sensitivity of +200 mV to the GND terminal
and the other has −200 mV. The circuit will be latched if the input signal is over the limit of either terminal.
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”.
It is rather recommended to use not "CLM+" but "CLM−" terminal, as the influence from the gate drive current of MOS
FET can be eliminated and wide voltage rating of +4 V to −4 V is guaranteed for absolute maximum rating.
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 Ω for R
some 200 µA from C
REJ03D0835-0300 Rev.3.00 Jun 06, 2008
Page 21 of 40
LM
terminal and C
Figure 9 Operating Waveforms of Current Limiting Circuit
OSC waveform of
CF terminal
Waveform of
CLM+ terminal
Current limit signal
to set latch
Waveform of
V
OSC waveform of
CF terminal
Waveform of
CLM− terminal
Current limit signal
to set latch
Waveform of
V
OUT
OUT
terminal
terminal
CLM
NF
is designed to have the enough value to absorb the noise voltage.
during the switching of power transistor due to the snubber circuit and stray
NF
because such range of R
V
(a) +current limit
V
(b) −current limit
THCLM
THCLM
≈ 200 mV
≈ −200 mV
NF
is not influenced by the flow-out current of
NF
and C
NF
is used as