M51995AP/AFP

REJ03D0835-0300 Rev.3.00 Jun 06, 2008

Page 27 of 40

As the OVP reset voltage is settled on the rather high voltage of 9.0 V, SMPS can be reset in rather short time from the

switch-off of the AC power source if the smoothing capacitor is not so large value.

OVP

GND

8 k

12 k

Q1

Q2

2.5 k

400

7.8 V

100

µA

Q3

Figure 20 Detail Diagram of OVP Circuit

8

7

6

5

4

2

0

3

1

0

5

10

15

25

35

20

30

40

OVP reset point

8.82 V (

−30 °C)

8.97 V (25

°C)

9.07 V (85

°C)

Ta = 25

°C

Ta = 85

°C

Ta =

−30 °C

Figure 21 Circuit Current vs. Supply Voltage (OVP Operation)

Output Section

It is required that the output circuit has the high sink and source abilities for MOS FET drive. It is well known that the

totempole circuit has high sink and source ability. However, it has the demerit of high through current.

For example, the through current may reach such the high current level of 1 A, if type M51995A has the “conventional”

totempole circuit. For the high frequency application such as higher than 100 kHz, this through current is very

This IC uses the improved totempole circuit, so without deteriorating the characteristic of operating speed, its through

current is approximately 100 mA.