Controllers cut standby power down to size

Edited by the Electronicstalk editorial team Jan 25, 2005

Two new families of PWM controllers address the growing industry need for switched mode power supply manufacturers to reduce the standby power consumption at input levels higher than 75W.

Two new families of PWM controllers address the growing industry need for switched mode power supply manufacturers to reduce the standby power consumption at input levels higher than 75W.

The NCP1230 and NCP1231 families of current mode controllers are ideal for power supply applications in notebook adapters, offline battery chargers and consumer electronics equipment.

The NCP1230/NCP1231 devices allow the power supply designer to shut down the power factor correction (PFC) stage in light or no-load conditions.

PFC is needed in power supply designs from 50 to 75W, but it typically becomes a liability by continuing to consume power at light loading.

This inherently lowers the overall conversion efficiency of the power supply.

The NCP1230 and NCP1231 families of PWM controllers are the only devices on the market offering the PFC shutdown feature.

"ON Semiconductor's NCP1230 and NCP1231 devices provide power supply designers with a unique tool to meet global power stand-by regulations", said Andy Williams, ON Semiconductor Director of Power Conversion Products.

"These current mode controllers are compatible with any power factor correction IC and address the challenges of improving efficiency and lowering EMI in both the active and standby power modes".

The NCP1230 and NCP1231 families are a series of current mode controllers offering cycle skipping at light loads, internal ramp compensation, and frequency dithering for improved EMI performance.

Both families feature the power factor shutdown feature and are available in three frequency options - 65, 100 and 133kHz.

A short-circuit protection independent of the auxiliary winding ensures a safe and robust design.

The NCP1230 integrates a 2.5ms soft-start, an internal high-voltage startup current source for lossless startup, and in the NCP1231 the soft-start is adjustable and a brownout function has been added.

The NCP1230A device also includes a proprietary soft-skipping mode at light loading which prevents acoustic noise generation.

The NCP1230 and NCP1231 families are offered in both SO-8 and PDIP-8 packages (minus pin 7) and are priced at between $0.48 and $0.53 per unit in 10,000-unit quantities.