STMicroelectronics VIPER50A

Overview

VIPER50A from STMicroelectronics is a high-voltage integrated primary-side SMPS controller combining a 700V avalanche-rugged vertical power MOSFET and current-mode PWM control circuitry in a single PowerSO-10™ package. It delivers up to 50W output in single-range configurations, features adjustable switching frequency up to 200 kHz, internal 13V VDD regulation, and automatic burst-mode operation for <1W standby consumption compliant with the German "Blue Angel" norm.

For engineers reviewing the VIPER50A datasheet, VIPER50A pinout, VIPER50A application, or VIPER50A equivalent, key selection considerations include its integrated 700V/1.5A MOSFET, programmable peak current limit (1.5–2.7 A), thermal shutdown at 140–170°C, and compatibility with both primary- and secondary-side regulation topologies using optocoupler feedback or auxiliary winding sensing.

Technical Context

The VIPER50A implements current-mode control with dual-loop regulation: an inner loop senses primary-side peak current via integrated SenseFET and compares it to the COMP pin voltage, while the outer loop uses transconductance error amplification (Gm = 1.1–1.9 mA/V) to adjust duty cycle. Its oscillator supports external Rt-Ct programming (e.g., 8.2 kΩ + 2.4 nF yields 100 kHz) and synchronization via the OSC pin.

Startup relies on an internal high-voltage current source connected to the DRAIN pin, enabling direct connection to rectified AC mains without auxiliary startup circuitry. Undervoltage lockout (UVLO) operates with hysteresis (VDDoff = 7.5–9 V, VDDon = 11–12 V), and overtemperature protection triggers at 140–170°C with 40°C hysteresis, latching shutdown until reset by VDD cycling.

Key Specifications

Pinout & Package

Package: PowerSO-10™ (022Y), surface-mount, thermally enhanced 10-pin package with exposed die pad for improved heat dissipation (R_thj-case = 1.9°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SMPS primary-side controller applications.

Compared with ICE2QS03G and LNK306P, VIPER50A offers unique programmability of switching frequency and peak current, full COMP pin accessibility for custom loop design, and integrated burst-mode logic - making it optimal for designers needing regulatory compliance, thermal resilience, and topology flexibility in 25–50W applications.

Availability

VIPER50A is available at Aetrix Electronics and suitable for AC-DC adapters, set-top box power supplies, smart meter auxiliary supplies, and industrial IoT sensor power requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for VIPER50A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, MCU, and automotive ICs with strong manufacturing and R&D infrastructure across Europe and Asia.

The VIPer™ family was designed specifically for highly integrated, cost-optimized offline SMPS in consumer and industrial applications - emphasizing high-voltage integration, low standby power, and simplified board layout without compromising reliability or safety compliance.

FAQ

What is the maximum continuous output power achievable with VIPER50A in a flyback design?

The VIPER50A supports up to 50W output in single-range configurations (e.g., 230 VAC input) and 25W in universal-input (85–265 VAC) designs. This assumes proper heatsinking (R_thj-amb ≤ 50°C/W), operation below 100°C junction temperature, and use of recommended transformer design guidelines from ST Application Note AN2359.

Can VIPER50A be used in primary-side regulation (PSR) without an optocoupler?

Yes - VIPER50A supports primary-side regulation using the auxiliary winding on the transformer to feed back to the VDD pin. The internal 13V regulator acts as a precision reference, and the COMP pin remains unconnected; regulation accuracy depends on transformer turns ratio stability and VDD clamping tolerance (±2% over temperature).

How does the internal blanking time prevent false triggering during MOSFET turn-on?

The VIPER50A applies a fixed 250 ns blanking window after each MOSFET turn-on event, during which the current-sense comparator is disabled. This avoids misinterpretation of high dv/dt-induced spikes from transformer leakage inductance or secondary rectifier reverse recovery, ensuring accurate peak current detection and stable PWM operation.

Is external synchronization of the switching frequency supported, and what are the electrical requirements?

Yes - the OSC pin accepts external TTL/CMOS clock signals for synchronization. Input pulses must be ≤500 ns wide, with amplitude between 0 V and V_DD, and driven by a low-impedance source. Exceeding 500 ns increases quiescent current; synchronization is disabled if the OSC pin voltage falls below 3.7 V or rises above 7.1 V (oscillator valley/peak thresholds).