TOP250F datasheet(25/52 Pages) POWERINT

25 / 52 page

TOP242-250

12/04

In addition to using a minimum number of components,

TOPSwitch-GX

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-GX

consumes very little power and the external circuitry does

not consume any current (either M, Lor X 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 ms 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

requiredtopowertheexternalcircuitryintheprimary. 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.

TOP250F 데이터시트(PDF) 25 Page - Power Integrations, Inc.