M51995AFP#CF0J Renesas Electronics America, M51995AFP#CF0J Datasheet - Page 25

• 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
Intermittent Action Circuit Section
Intermittent action circuit will start to operate when the output signal from the intermittent action and oscillation control
circuit are “high” and also VF terminal voltage is lower than V
Figure 12 shows the block diagram of intermittent action circuit. Transistor Q is on state when VF terminal voltage is
higher than V
When VF terminal voltage is lower than V
Under this condition, if the intermittent action and oscillation control signal become “high” the switch SWA will close
only in this “high” duration and C
potential will rise. The output pulse can be generated only this duration. When the CT terminal voltage reaches to 8 V,
the control logic circuit makes the SW
The IC operation will be ceased in the falling duration.
On the other hand, when CT terminal voltage decreases to lower than 2 V, the IC operation will be reset to original state,
as the control logic circuit makes the SW
Therefore the parts in power circuit including secondary rectifier diodes are protected from the overheat by the over
current.
Figure 14 shows the I
In this duration the power is not supplied to IC from the third winding of transformer but through from the resistor R1
connected to V
If the R1 shown in Application Example is selected adequate value, V
low but adequate value, as the I
To ground the CT terminal is recommended, when the intermittent mode is not used.
In this case the oscillated frequency will become low but the IC will neither stop the oscillation nor change to the
intermittent action mode, when the current limit function becomes to operate and the VF terminal voltage becomes low.
REJ03D0835-0300 Rev.3.00 Jun 06, 2008
Page 23 of 40
THTIME
CC
line.
of about 3 V, so the CT terminal voltage is near to GND potential.
CC
versus V
Figure 12 Block Diagram of Intermittent Action Circuit
VF
V
CC
THTIME
CC
T
versus V
is charged up by the current of 120 µA through SW
in this timer-off duration.
Figure 13 Waveform of CT Terminal
A
−
+
(≈ 3 V)
“off” and SW
A
THTIME
“on” and SW
CC
characteristics has such the one shown in figure 14.
No operating
, Q becomes “off” and the CT has the possibility to be charged up.
duration
Q
B
“on”, in order to flow in the I
CT
B
“off”.
+
C
T
THTIME
2 V
SW
SW
I
(≈ 120 µA)
I
(≈ 15 µA)
TIMEON
TIMEOFF
A
B
of about 3 V.
CC
A
B
8 V
terminal voltage will be kept at not so high or
Control
logic
TIMEOFF
A
(SW
of 15 µA to CT terminal.
B
is open) and CT terminal