STEVAL-ISA042V1

The STEVAL-ISA042V1 is an evaluation board designed to fit into the DC/DC & AC/DC (Off-Line) SMPS product family. It illustrates a controller based supply featuring the STGIPNOL80A and provides a reference design for a 1 W output power supply with an input range from 90 to 265 V AC.

The main features of this product are the following:

• Wide input voltage range: from 90 to 265 V AC
• High efficiency up to 85%
• Protected against over-voltage, over-temperature, over-current and overload conditions
• Compact design (board size: 74.68 x 107.95 mm)
• Cost effective solution

The STEVAL-ISA042V1 is designed based on an AC/DC flyback topology with an auxiliary winding for the bias of the main main power switch. The standby power for the IC is supplied through the auxiliary winding of the transformer, while the auxiliary pin of the controller is used for the detection of the zero crossing of the AC line voltage. The power stage features an LLC Resonant converter with two isolated outputs for the main output and for the standby output connection. The stand-by part provides a regulated 5VDC output voltage.

The main output is realized using a single active power switch connected to the primary side of the transformer which is driven by the STGIPNOL80A. The primary side is also rectified using a diode and a snubber circuit to reduce the voltage spikes. The output power is determined by a feedback network consisting of an opto-coupler (CTR: 200%) and an external reference voltage. The reference voltage can be adjusted using a 10-turn precision trimmer potentiometer (VR1).

The STEVAL-ISA042V1 also provides an additional protection mechanism in case of over temperature, over current or overload conditions. The input line is equipped with an inrush current limiter and an over voltage protection circuit. The thermal protection is provided through an NTC thermistor placed close to the main power switch. The maximum power dissipated by the main power switch is monitored using a monitoring chip (LM75B).

The STEVAL-ISA042V1 is an ideal evaluation board for anyone requiring a low cost, efficient and reliable energy conversion solution. It provides all the necessary components for a complete DC/DC & AC/DC (Off-Line) SMPS and the board size is small enough to be used in a wide variety of applications.

The STEVAL-ISA042V is just one example of a high performance, cost effective DC/DC and AC/DC (Off-Line) SMPS solution offered by STMicroelectronics. With its wide input voltage range, high efficiency, and small footprint, it can be used in a variety of applications, including power supplies for consumer, industrial, and automotive applications.