STMicroelectronics – The STNRG digital-controller family : Easy-to-configure controllers simplify digital power conversion

The STNRG digital-controller family from STMicroelectronics provides an easy way for designers to implement an efficient digital power-conversion system with enhanced safety features and generous provision of diagnostic information.

The rugged STNRG ICs contain ST’s unique State Machine Event Driven (SMED) high resolution PWM generator, together with an 8-bit supervisory controller core. The SMED circuitry is a proven method for implementing high-performance digital control in STLUX ICs for LED lighting.

The STNRG parts also include a 32kbyte EEPROM, 6kbyte RAM, an ADC, op amp, I2C port and general-purpose I/Os.

Configuring the SMED calls for no specialist software expertise, unlike the usual DSP- or microcontroller-based approaches to digital power control.

The SMED can be triggered from the internal timer or by an external event such as peak current, over-current or zero crossing. This enables a peak-current detecting buck converter, with constant off-time set by the timer, to operate without intervention by the core processor. A simple proportional-integral loop executed in the core sets the peak-current value for output regulation.

The STNRG family is comprised of the STNRG288A with four SMED-controlled outputs, the STNRG328A with five SMED outputs, and the STNRG388A with six SMED outputs. Designers have the option to connect two SMED cells together to generate dual gate-drive signals with inserted dead time for half-bridge configurations.


  • Four analogue comparators
  • Internal 96MHz PLL
  • System, auxiliary and basic timers
  • Multiple low-power modes
  • UART interface
  • I2C master/slave interface
  • Operating-temperature range: -40°C to 105°C


  • High-end industrial applications
  • Solar-power converters
  • Electric-vehicle charging stations
  • Industrial switched-mode power supplies



The EVLSTNRG-170W evaluation board is intended for evaluating the STNRG388A digital controller in off-line power-conversion applications. The board implements a PFC stage followed by a resonant LLC stage, supplying a load of up to 170W.
Orderable Part Number: EVLSTNRG-170W