M51995AP/AFP

REJ03D0835-0201 Rev.2.01 Nov 14, 2007

Page 16 of 40

Function Description

Type M51995AP and M51995AFP are especially designed for off-line primary PWM control IC of switching mode

power supply (SMPS) to get DC voltage from AC power supply.

Using this IC, smart SMPS can be realized with reasonable cost and compact size as the number of external electric

parts can be reduced and also parts can be replaced by reasonable one.

In the following circuit diagram, MOS FET is used for output transistor, however bipolar transistor can be used with no

problem.

Start-up Circuit Section

The start-up current is such low current level as typical 90

µA, as shown in figure 1, when the V

CC voltage is increased

from low level to start-up voltage VCC(START).

In this voltage range, only a few parts in this IC, which has the function to make the output voltage low level, is alive

and ICC current is used to keep output low level. The large voltage difference between VCC(START) and VCC(STOP) makes

start-up easy, because it takes rather long duration from VCC(START) to VCC(STOP).

Supply Voltage VCC (V)

ICCO

≈ 14 mA

ICCL

≈ 90 µA

VCC

(STOP)

≈ 9.9 V

VCC

(START)

≈ 16.2 V

Figure 1 Circuit Current vs. Supply Voltage