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ON Semi PWM controllers with PFC shut-down feature

Posted: 03 Feb 2005 ?? ?Print Version ?Bookmark and Share

Keywords:pwm controller? on semiconductor? switched mode power supply? smps? ncp1230?

The new PWM controllers from ON Semiconductor address the need of Switched Mode Power Supplies (SMPS) manufacturers to reduce the standby power consumption at input levels higher than 75W.

According to the press release, the NCP1230 and NCP1231 devices allow the power supply designer to shut-down the Power Factor Correction (PFC) stage in light or no-load conditions. Both families of PWM controllers are the only devices on the market offering the PFC shut-down feature, touted ON Semi.

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

"ON Semiconductor's NCP1230 and NCP1231 devices provide power supply designers with a unique tool to meet global power stand-by regulations," commented Andy Williams, the company's director for its Power Conversion products. "These current mode controllers are compatible with any power factor correction IC and address the challenges of improving efficiency and lowering electromagnetic interference (EMI) in both the active and stand-by power modes."

The two current mode controllers offer cycle skipping at light loads, internal ramp compensation and frequency dithering for improved EMI performance. Both product families are available in three frequency options65kHz, 100kHz and 133kHz. A short-circuit protection independent of the auxiliary winding insures a safe and robust design.

The NCP1230 integrates a 2.5ms soft-start and an internal high-voltage start-up current source for lossless start-up; while in the NCP1231, the soft start is adjustable and a brown out function has been added. The NCP1230A also includes a proprietary soft-skipping mode at light loading that prevents acoustic noise generation.

Both the NCP1230 and NCP1231 families are offered in SO-8 and PDIP-8 packages (minus pin # 7) and are priced at 50 cents per unit in 10,000-piece quantities.

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