April 2009

Doc ID 15305 Rev 1

1/23

AN2872

Application note

Super wide-range buck converter based on the VIPer16

1

Introduction

This document describes the STEVAL-ISA010V1 demonstration board, which is designed

as an example of a simple non-isolated auxiliary power supply for a range of input voltages

from 85 VAC to 500 VAC.

There is an ever-increasing demand for small power supplies capable of working without

voltage range limitations, even at nominal levels of 400 VAC and 415 VAC, respectively. The

real voltage levels can reach 500 VAC (415 V + 20%). The major markets for this type of

SMPS are home appliances and metering.

The new STMicroelectronics™ family of monolithic converters is well-suited for this range of

input voltages, thanks to the 800 V avalanche-rugged MOSFET integrated within the same

package with the control chip. This application note describes a low power SMPS with

a buck topology using STMicroelectronics’ VIPer16 fixed-frequency off-line converter as

a main circuit. The VIPer16 device includes an 800 V rugged power switch, a PWM

controller, programmable overcurrent, overvoltage, overload, a hysteretic thermal protection,

soft-start and safe auto-restart after any fault condition removal. Burst mode operation at

light load combined with the very low consumption of the device helps to meet standby

energy-saving regulations. The significant benefit of this new chip derives from the jitter of

the switching frequency and the possibility to supply the chip directly from the DC HV bus,

so auxiliary supply is not mandatory. The VIPer16 is suitable for flyback or buck topologies,

and thanks to an internal self-supply circuit it does not require an auxiliary supply.

Figure 1.

The STEVAL-ISA010V1 demonstration board

www.st.com