TOP201 データシートの表示（PDF） - Power Integrations, Inc

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TOP201

Three-terminal Off-line PWM Switch

Power Integrations, Inc 

TOP200-4/14

VIN

VIN

DRAIN

0

VOUT

0

IOUT

0

VC

0

IC 0

12

812

•••

•••

81

12

812

•••

•••

81

45 mA

VC(reset)

1

2

3

4

1

PI-1119-110194

Figure 6. Typical Waveforms for (1) Normal Operation, (2) Auto-restart, (3) Latching Shutdown, and (4) Power Down Reset.

Shutdown/Auto-restart

To minimize TOPSwitch power

dissipation, the shutdown/auto-restart

circuit turns the power supply on and off

at a duty cycle of typically 5% if an out

of regulation condition persists. Loss of

regulation interrupts the external current

into the CONTROL pin. V regulation

C

changes from shunt mode to the

hysteretic auto-restart mode described

above. When the fault condition is

removed, the power supply output

becomes regulated, V regulation returns

C

to shunt mode, and normal operation of

the power supply resumes.

Latching Shutdown

The output overvoltage protection latch

is activated by a high-current pulse into

the CONTROL pin. When set, the latch

turns off the TOPSwitch output.

Activating the power-up reset circuit by

removing and restoring input power, or

momentarily pulling the CONTROL pin

below the power-up reset threshold resets

the latch and allows TOPSwitch to

resume normal power supply operation.

V is regulated in hysteretic mode when

C

the power supply is latched off.

Overtemperature Protection

Temperature protection is provided by a

precision analog circuit that turns the

output MOSFET off when the junction

temperature exceeds the thermal

shutdown temperature (typically 145°C).

Activating the power-up reset circuit by

removing and restoring input power or

momentarily pulling the CONTROL pin

below the power-up reset threshold resets

the latch and allows TOPSwitch to

resume normal power supply operation.

V is regulated in hysteretic mode when

C

the power supply is latched off.

High-voltage Bias Current Source

This current source biases TOPSwitch

from the DRAIN pin and charges the

CONTROL pin external capacitance

(C ) during start-up or hysteretic

T

operation. Hysteretic operation occurs

during auto-restart and latched

shutdown. The current source is switched

on and off with an effective duty cycle of

approximately 35%. This duty cycle is

determined by the ratio of CONTROL

pin charge (I ) and discharge currents

C

(I and I ). This current source is

CD1

CD2

turned off during normal operation when

the output MOSFET is switching.

5 D

7/96

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