M51995AP/AFP
How to Get the Narrow Pulse Width During the Start of Operation
Figure 43 shows how to get the narrow pulse width during the start of the operation. If the pulse train of forcedly
narrowed pulse-width continues too long, the misstart of operation may happen, so it is recommended to make the
output pulse width narrow only for a few pulse at the start of operation. 0.1µF is recommended for the C.
F/B
M51995A
100 Ω
To photo
coupler
C
Figure 43 How to Get the Narrow Pulse Width During the Start of Operation
How to Synchronize with External Circuit
Type M51995A has no function to synchronize with external circuit, however, there is some application circuit for
synchronization as shown in figure 44. If this circuit is used, the synchronization may be out of order at the overload
condition when the current limiting function starts to operate and VF terminal voltage becomes lower than 3 V.
M51995A
T-ON
CF
T-OFF
CT
+
CT
RON
CF
ROFF
120 µA
Synchronous
pulse
Q1
Q2
Oscillating
waveform
0 V
Synchronize
waveform
0 V
Minimum pulse width of
synchronous pulse
Maximum pulse width of
synchronous pulse
Figure 44 How to Synchronize with External Circuit
REJ03D0835-0300 Rev.3.00 Jun 06, 2008
Page 38 of 40
RENESAS [ RENESAS TECHNOLOGY CORP ]
