STMicroelectronics VIPER222XSTR

Overview

VIPER222XSTR from STMicroelectronics is a 730 V high-voltage offline PWM converter IC integrating a rugged power MOSFET, current-mode PWM controller, 1.2 V reference, frequency jittering, and burst-mode operation. It delivers up to 11 W in enclosed adapters and 13 W in open-frame designs at 230 VAC, supports flyback/buck topologies, and enables auxiliary SMPS in home appliances and industrial lighting with no external startup resistor required.

For engineers reviewing the VIPER222XSTR datasheet, VIPER222XSTR pinout, VIPER222XSTR application, or VIPER222XSTR equivalent, key selection criteria include its 30 kHz nominal switching frequency, 730 V avalanche-rated drain, integrated soft-start (8 ms), 40 mW no-load input power, and SSOP10 thermal performance with 155 °C/W junction-to-ambient resistance on minimal copper.

Technical Context

The VIPER222XSTR implements current-mode control with internal primary-side current sensing, enabling cycle-by-cycle OCP at 0.62 A typical. Its feedback loop operates via either resistor divider (non-isolated) or optocoupler-coupled external error amplifier (isolated), with EA-IN/EA-OUT pins supporting both configurations.

Startup uses an integrated high-voltage current source (ICH1 = −1.4 mA typ.) that charges VCC through DRAIN, eliminating external bias windings. Protection includes thermal shutdown at 155 °C, short-circuit recovery with 1.2 s restart delay, and VCC clamp protection triggered after 500 µs overvoltage exposure.

Key Specifications

Pinout & Package

Package: SSOP10 (ECOPACK® compliant), 4.9 mm × 6.0 mm × 1.75 mm body height, 0.65 mm pitch, exposed DRAIN pads for thermal conduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage offline SMPS controller applications.

Compared with VIPER222XSTR, ICE2QS03G trades EMI performance and standby efficiency for lower unit cost, while LNK306P sacrifices feedback flexibility for enhanced safety integration - neither matches the 730 V ruggedness, dual-mode feedback, and 40 mW no-load capability of the VIPER222XSTR in compact auxiliary SMPS.

Availability

VIPER222XSTR is available at Aetrix Electronics and suitable for home appliance auxiliary power, industrial LED driver supplies, and smart thermostat power systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant SSOP10 packaging.

Supply support for VIPER222XSTR 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, designing and manufacturing microcontrollers, power ICs, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The VIPER™ family targets cost-sensitive, high-reliability offline SMPS applications, emphasizing integration, ruggedness, and regulatory compliance - with VIPER222XSTR specifically engineered for 30 kHz flyback/buck converters in space-constrained auxiliary power designs.

FAQ

What is the maximum continuous output power achievable with VIPER222XSTR at 230 VAC?

The VIPER222XSTR delivers up to 13 W in open-frame designs with adequate heat sinking (100 mm² copper), and 11 W in non-ventilated enclosed adapters at 50 °C ambient. Power capability is thermally limited by R_TH-JA = 155 °C/W on minimal copper; increasing copper area to 100 mm² reduces R_TH-JA to 95 °C/W, enabling full 13 W operation.

How does the burst mode function reduce audible noise in low-load conditions?

Burst mode activates when EA-OUT falls below 0.8 V, reducing peak drain current from 0.62 A to 130 mA and lowering switching frequency below 15 kHz. This avoids mechanical resonance in transformers and inductors within the 20–200 Hz audible range, eliminating buzz without compromising regulation accuracy or requiring external audio-suppression circuitry.

Can VIPER222XSTR be used in isolated flyback topologies without an external error amplifier?

No - for isolated flyback, the internal error amplifier must be disabled by connecting EA-IN to GND, and regulation requires an external TL431-type shunt regulator on the secondary side coupled via optocoupler to EA-OUT. The device does not support direct secondary-side feedback; EA-OUT serves solely as the control interface for the optocoupler's phototransistor collector.

What thermal design considerations apply to the DRAIN pins in SSOP10 package?

All five DRAIN pins (6–10) are electrically and thermally paralleled and must be connected to a shared PCB copper area. For 13 W operation, ST recommends ≥100 mm² of 35 µm-thick copper (0.155 in²) to achieve R_TH-JA = 95 °C/W; insufficient copper causes thermal derating - e.g., 25 mm² raises R_TH-JA to ~130 °C/W, limiting practical power to ~8 W at 50 °C ambient.