STMicroelectronics VIPER222LSTR

Overview

VIPER222LSTR from STMicroelectronics is a 730 V high-voltage PWM controller with integrated avalanche-rugged power MOSFET, optimized for flyback and buck topologies. It operates at 54–66 kHz switching frequency, delivers up to 13 W in open-frame designs, features 1.2 V internal reference, frequency jittering for EMI reduction, and burst-mode operation enabling ≤40 mW no-load input power at 230 VAC - used in auxiliary SMPS for home appliances and industrial lighting.

For engineers reviewing the VIPER222LSTR datasheet, VIPER222LSTR pinout, VIPER222LSTR application, or VIPER222LSTR equivalent, key selection considerations include its integrated high-voltage startup current source, DRAIN-referenced OCP threshold (0.62 A typ.), thermal shutdown at 155 °C, and SSOP10 package with five DRAIN terminals for enhanced thermal dissipation.

Technical Context

The VIPER222LSTR implements current-mode PWM control with internal error amplifier (EA-IN/EA-OUT), cycle-by-cycle primary current sensing, and dual-loop protection: OCP triggers at 0.62 A (ILIM) with pulse skipping below tON(MIN) = 350 ns, while short-circuit protection activates after 440 ms overload delay (tOVLmax) followed by 1.2 s restart. Its soft-start time is fixed at 8 ms (tSS).

Startup relies on a three-stage high-voltage current source (ICH1/ICH2/ICH3) drawn from DRAIN to charge VCC, disabling once VCC reaches 16 V (VON); VCC is clamped at 30 V (VCLAMP) with overcurrent shutdown after 500 µs (tCC_FAIL). Feedback supports both primary-side resistor-divider regulation and secondary-side optocoupler-based isolation via EA-OUT voltage modulation between 0.8 V (VEA-BM) and 3 V (VEA-SAT).

Key Specifications

Pinout & Package

Package: SSOP10 (3.9 × 4.9 mm, 1.25 mm height), RoHS-compliant ECOPACK® with exposed thermal pad recommended for PCB copper area mounting to achieve RTH-JA = 95 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICE2QS03G and VIPER06XS, the VIPER222LSTR uniquely combines 730 V ruggedness, frequency jittering, and burst-mode operation to deliver certified Level VI standby performance in minimal board area - making it optimal for cost-sensitive, space-constrained auxiliary supplies.

Availability

VIPER222LSTR is available at Aetrix Electronics and suitable for home appliance auxiliary SMPS, industrial lighting drivers, and consumer electronics adapters requiring stable component supply across multi-year production cycles.

Supply support for VIPER222LSTR 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The VIPER™ family targets highly integrated, cost-optimized offline AC-DC conversion - specifically engineered to replace discrete MOSFET + controller designs in auxiliary and low-power primary-side regulated SMPS.

FAQ

What is the maximum continuous output power achievable with VIPER222LSTR in an open-frame design?

The VIPER222LSTR delivers up to 13 W continuous output power in open-frame configurations at 50 °C ambient temperature when mounted on a PCB with 100 mm² of 35 μm-thick copper. This rating assumes adequate heat sinking and accounts for thermal resistance of 95 °C/W (junction-to-ambient) under those conditions, as specified in Table 2 of DS13192 Rev 2.

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

Burst mode activates when EA-OUT falls below 0.8 V (VEA-BM), reducing DRAIN peak current to 105–155 mA (ILIM_BM) and lowering switching frequency well below 20 kHz - the human audible range. This eliminates coil whine caused by magnetostriction in transformers operating near resonance, while maintaining regulation without sacrificing efficiency.

Can VIPER222LSTR 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; regulation requires an external TL431 or equivalent on the secondary side, with feedback transferred via optocoupler to modulate EA-OUT voltage between 0.8 V and 3 V. The internal EA is only used in non-isolated configurations.

What is the purpose of the five paralleled DRAIN pins in the SSOP10 package?

The five DRAIN pins (pins 6–10) are internally connected to the MOSFET drain and serve to reduce both electrical resistance and thermal impedance. They allow direct connection to large PCB copper areas for heat dissipation and lower parasitic inductance - critical for managing 730 V avalanche energy and sustaining 2 A pulse current without excessive voltage overshoot.