TOP242-249 POWERINT [Power Integrations, Inc.], TOP242-249 Datasheet - Page 26

• Manufacturer Part Number: TOP242-249
• Description: Family Extended Power, Design Flexible,Integrated Off-line Switcher
• Manufacturer: POWERINT [Power Integrations, Inc.]

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
2. A very low cost, low voltage/current, momentary contact
3. No debouncing circuitry for the momentary switch is required.
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TOP242-249
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, L or X pin is open) from
the high voltage DC input.
switch can be used.
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
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4. No external current limiting circuitry is needed for the
5. No high voltage resistors to the input DC voltage rail are
6. Robust design: There is no on/off latch that can be accidentally
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.
operation of the U4 optocoupler output due to internal
limiting of M pin current.
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.
triggered by transients. Instead, the power supply is held in
the on-state through the secondary side microprocessor.