AN8029 查看數據表（PDF） - Panasonic Corporation

零件编号

产品描述 (功能)

生产厂家

AN8029

Self-excited RCC pseudo-resonance type AC-DC switching power supply control IC

Panasonic Corporation 

Voltage Regulators

s Terminal Equivalent Circuits (continued)

Pin No.

Equivalent circuit

8

VCC

7.3 V

Comp.

5 µA

8

9

VCC

TON

9

AN8029

Description

I/O

TIM/OVP:

I

Terminal for use both OVP (overvoltage protec-

tion circuit) and timer latch.

[OVP]

When overvoltage signal of the power supply is

detected and high is inputted to the terminal, it

turns off the internal circuit. At the same time, it

holds that condition (latch). To reset the OVP latch,

the VCC should be decreased to a voltage lower

than the release voltage.

[Timer latch]

It detects the output voltage fall due to the

overcurrent condition of the power supply output

through the current level inputted to IFB. When

the IIFB decreases under the current of certain

value, the charge current flows in the capacitor

which is connected to this terminal. Then, when

the capacitor is charged up to the threshold volt-

age of the OVP, the OVP works so that the IC

could keep the operation stop condition.

FB:

I

Terminal for connecting the photocoupler for er-

ror voltage feedback of the power supply output.

It is possible to cancel about 180 mA of the dark

current of photocoupler.

s Application Notes

[1] Operation descriptions

1. Start/stop circuit block

• Start mechanism

When AC voltage is applied and the sup-

ply voltage reaches the start voltage through

the current from start resistance, the IC starts

operation. Then the power MOSFET driving

starts. Thereby, bias is generated in the trans-

former and the supply voltage is given from

the bias coil to the IC. (point a in figure 1)

During the period from the time when the

start voltage is reached and the voltage is gen-

erated in the bias coil to the time when the IC

is provided with a sufficient supply voltage,

the supply voltage of the IC is supplied by the

capacitor (C8) connected to VCC .

After AC rectification

Start resistance

R1

VCC

C8

VOUT

GND

Start

voltage

Stop

voltage

Before start

a

Start

Voltage supplied

from bias coil

Start condition

b

Figure 1

c Start failure

5

Share Link: