TOP234P datasheet(18/38 Pages) POWERINT

18 / 38 page

Rev. D 10/20

TOP232-234

www.power.com

In addition to using a minimum number of components,

TOPSwitch-FX provides many technical advantages in this

type of application:

1. Extremely low power consumption in the off mode: 80 mW

typical at 110 VAC and 160 mW typical at 230 VAC. This is

because in the remote/off mode the TOPSwitch-FX

consumes very little power, and the external circuitry does

not consume any current (M pin is open) from the high-

voltage DC input.

2. A very low cost, low voltage/current, momentary contact

switch can be used.

3. No debouncing circuitry for the momentary switch is

required. During turn-on, the start-up time of the power

supply (typically 10 to 20 ms) plus the microprocessor

initiation time act as a debouncing filter, allowing a turn-on

only if the switch is depressed firmly for at least the above

delay time. During turn-off, the microprocessor initiates the

shutdown sequence when it detects the first closure of the

switch, and subsequent bouncing of the switch has no

effect. If necessary, the microprocessor could implement

the switch debouncing in software during turn-off, or a filter

capacitor can be used at the switch status input.

4. No external current limiting circuitry is needed for the

operation of the U4 optocoupler output due to internal

limiting of M pin current.

5. No high-voltage resistors to the input DC voltage rail are

required to power the external circuitry in the primary. Even

the LED current for U3 can be derived from the CONTROL

pin. This not only saves components and simplifies layout,

but also eliminates the power loss associated with the

high-voltage resistors in both on and off states.

6. Robust design: There is no on/off latch that can be

accidentally triggered by transients. Instead, the power

supply is held in the on-state through the secondary side

microprocessor.

TOP234P データシート(PDF) 18 Page - Power Integrations, Inc.

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