STMicroelectronics VIPER28HN

Overview

VIPER28HN from STMicroelectronics is a high-voltage AC-DC converter IC integrating an 800 V avalanche-rugged power MOSFET, current-mode PWM controller, and embedded HV startup circuit. It delivers up to 26 W peak power at 230 VAC, operates at 115 kHz (H-type), achieves ≤30 mW no-load consumption, and features dual OCP thresholds (0.8 A and 1.2 A) for transformer saturation and secondary diode short-circuit protection. It is used in auxiliary power supplies for smart meters and energy data concentrators.

For engineers reviewing the VIPER28HN datasheet, VIPER28HN pinout, VIPER28HN application, or VIPER28HN equivalent, key selection considerations include its 115 kHz switching frequency, 800 V drain-source breakdown, EPT-enabled overload sustain capability, and DIP-7 package thermal performance with R_thJA = 90 °C/W on standard FR4.

Technical Context

The VIPER28HN implements a current-mode flyback controller with integrated 800 V power switch, enabling ultra-wide input range (85–265 VAC) without external HV startup components. Its oscillator includes ±8 kHz frequency jitter at 115 kHz nominal to reduce EMI peaks, and burst-mode operation below 0.6 V on FB pin ensures <30 mW no-load consumption.

Protection architecture includes two-tier overcurrent detection: cycle-by-cycle limiting at 0.8 A (adjustable via CONT pin resistor) and second-level hiccup-mode shutdown at 1.2 A. Output overvoltage protection triggers at 3.0 V (±0.3 V) on FB with 2.2 µs digital strobe filtering, while thermal shutdown activates at 155 °C with 30 °C hysteresis.

Key Specifications

Pinout & Package

VIPER28HN is housed in a 7-pin DIP (Dual In-line Package) with exposed drain pads (pins 1, 2, 7) for enhanced thermal dissipation. The package complies with JEDEC MS-001 and supports through-hole mounting on standard FR4 PCBs with ≥100 mm² copper pour under drain pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICE3B0565J, VIPER28HN offers superior surge robustness and lower standby loss; versus VIPER06HS, it delivers higher peak power and tighter EMI control via 115 kHz jitter-making it optimal for compact, high-density 26 W auxiliary supplies.

Availability

VIPER28HN is available at Aetrix Electronics and suitable for smart energy metering, industrial data concentrators, and low-cost AC-DC adapters requiring stable component supply across multi-year production cycles.

Supply support for VIPER28HN 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, MCU, power, and sensing solutions for industrial, automotive, and consumer markets.

VIPER28HN belongs to the VIPerPlus family of high-voltage offline controllers, engineered specifically for cost-optimized, low-component-count AC-DC conversion in auxiliary and adapter applications demanding high reliability and energy efficiency.

FAQ

What is the maximum continuous output power achievable with VIPER28HN in an open-frame design?

VIPER28HN delivers up to 12 W continuous output power in an open-frame configuration at 50 °C ambient temperature with adequate heat sinking, as verified in ST's reference design AN4027. Peak power reaches 20 W for ≤2 seconds using the Extra Power Timer function, limited by thermal derating above 60 °C ambient.

How does the EPT (Extra Power Timer) function operate, and what capacitor value is required for a 3-second overload window?

The EPT pin uses an external capacitor to set overload sustain time: C_EPT = t_EPT / 5.6 µA. For a 3-second window, a 536 nF capacitor (e.g., 560 nF standard value) is required. During overload, the IC maintains switching until the EPT capacitor discharges to 0.6 V, then enters hiccup mode. The pin must be tied to GND if unused.

Can VIPER28HN replace VIPER22A in an existing design, and what layout changes are needed?

VIPER28HN is not a drop-in replacement for VIPER22A due to different pin functions: VIPER22A's pin 4 is SOURCE, while VIPER28HN's pin 4 is VDD. Layout changes required include re-routing VDD supply to pin 4, relocating the feedback network to pin 6 (FB), and connecting the EPT capacitor to pin 8. Thermal pad area under drain pins (1,2,7) must also be enlarged per ST's DIP-7 thermal guidelines.

What is the recommended minimum creepage distance between DRAIN pins and low-voltage traces on the PCB?

Per IEC 62368-1 and ST's layout recommendations, minimum creepage distance from any DRAIN pin (1,2,7) to low-voltage traces (GND, FB, CONT, VDD) must be ≥4.0 mm for reinforced insulation at 300 V RMS working voltage. ST recommends using slots or isolation gaps under the DIP-7 body and avoiding routing low-voltage traces beneath the package footprint.