The STMicroelectronics VIPER17LDTR is an offline flyback switching regulator from the VIPer™ plus series, integrating the 800 V power MOSFET and PWM controller. It delivers up to 10 W in a flyback topology, switching at 60 kHz with a 70% maximum duty cycle. Built-in fault protections — current limiting, over-temperature, and over-voltage — cover common failure modes. The wide Vcc range (8.5 V to 23.5 V) and 14 V start-up threshold suit universal AC-input designs for auxiliary power bricks, appliance control boards, and industrial SMPS.
60 kHz switching — transformer and EMI planning
At 60 kHz, the transformer core size for a 10 W flyback is manageable. That frequency is low enough to keep MOSFET switching losses manageable with the 800 V device, yet high enough that the transformer does not dominate the BOM footprint. Plan the EMI filter corner around the 60 kHz fundamental and its second harmonic. The 70% duty-cycle ceiling gives enough on-time margin for low-line bulk cap charging without hitting the current limit prematurely.
Protection set reduces external component count
The over-temperature protection (OTP) on the die — yes, it is built in — shuts down the gate drive if the junction hits the thermal limit, which is useful for a 10 W supply in a sealed enclosure where airflow is zero. Over-voltage protection (OVP) on the Vcc pin prevents runaway if the auxiliary winding feedback opens. Current limiting is cycle-by-cycle, so a shorted output does not cook the transformer before the fuse blows. All three protections are internal; no external comparator or reset IC needed.