Off-line converter enables ultra-low-power aux/domestic PSUs

July 21, 2016 // By Graham Prophet
Aimed at power supplies in smart home and industrial applications this high-voltage power converter enables ultra-low-consumption, simple, and cost-effective SMPSs with a 5V output for home appliances, building, lighting, and motion control, as well as small industrial and consumer applications.

ST’s VIPER01 operates directly from a rectified mains supply and integrates an 800V avalanche-rugged Power MOSFET with PWM (Pulse-Width Modulation) current-mode control and multiple protection circuits. The converter is tailored to provide the auxiliary supply to microcontrollers in IoT devices that are permanently connected to the Internet or a local network.

The new device belongs to the VIPerPlus family of high-voltage converters, now in its second generation, and uses ST’s BCD (Bipolar-CMOS-DMOS) technology. BCD allows the integration in a single chip of a high-performance PWM controller with a high-voltage logic-level control transistor, protection and diagnostic circuitry, without significantly impacting the robustness and reliability of the power transistor.

VIPER01 enables designers to meet the most stringent energy-saving standards, as it has very low power consumption and switches automatically to pulse frequency modulation under light load conditions. It can be used in fly-back, buck, and buck-boost converter topologies, while the integrated high-voltage start-up, sense-FET, error amplifier, and oscillator with jitter allow a complete application to be designed with the minimum number of external components.

Features of the VIPER01 include:

  • 800 V avalanche-rugged Power MOSFET allowing ultra-wide VAC input range;
  • Embedded HV start-up and sense-FET;
  • Current mode PWM controller;
  • Drain current limit protection;
  • Wide supply-voltage range from 4.5V to 30V;
  • Self-supply option allows auxiliary winding or bias components to be removed;
  • Jittered switching frequency reduces the EMI filter cost;
  • Embedded error amplifier with 1.2V reference voltage;
  • Protections with automatic restart include overload/short-circuit, line or output OVP, maximum duty cycle counter, VCC clamp;
  • Embedded thermal shutdown;
  • Built-in soft-start for improved system reliability.

The VIPER01 comes with a set of tools including evaluation kits, application notes, and spice models to jumpstart more robust, safer, and cost-effective SMPS designs, and costs $0.364 (1,000)

STMicroelectronics; www.st.com/viperplus