M51995AP/AFP

REJ03D0835-0300 Rev.3.00 Jun 06, 2008

Page 38 of 40

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. 0.1

µF is recommended for the C.

M51995A

F/B

To photo

coupler

100

Ω

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

Q1

Q2

+

120

µA

Synchronous

pulse

0 V

0 V

Maximum pulse width of

synchronous pulse

Minimum pulse width of

synchronous pulse

Synchronize

waveform

Oscillating

waveform

Figure 44 How to Synchronize with External Circuit