STMicroelectronics VIPER37HE

Overview

VIPER37HE from STMicroelectronics is a fixed-frequency offline AC-DC converter IC integrating an 800 V avalanche-rugged N-channel power MOSFET, current-mode PWM controller, dual overcurrent protection (OCP), output overvoltage protection (OVP), brownout detection, hysteretic thermal shutdown, and onboard soft-start. It delivers up to 20 W in open-frame designs at 50 °C ambient and achieves 30 mW standby power at 265 Vac. Used in auxiliary supplies for ATX systems and low-power adapters.

For engineers reviewing the VIPER37HE datasheet, VIPER37HE pinout, VIPER37HE application, or VIPER37HE equivalent, key selection criteria include its 115 kHz switching frequency (H-type), adjustable cycle-by-cycle current limit via CONT pin, 800 V drain-source breakdown, burst-mode operation for light-load efficiency, and integrated high-voltage startup circuit eliminating external bias winding.

Technical Context

The VIPER37HE implements a current-mode flyback controller with internal oscillator jittering (±8 kHz modulation depth at 250 Hz) to reduce EMI filter cost. Its dual OCP includes primary-side cycle-by-cycle limiting (1 A typ.) and secondary-level hiccup-mode protection (1.7 A threshold).

Brownout protection uses a dedicated BR pin with 0.45 V threshold and 50 mV hysteresis, while OVP is strobed and digitally filtered on the CONT pin with 3.0 V threshold and 2.2 µs strobe time. The device enters burst mode when FB voltage falls below 0.6 V, reducing peak drain current to 160 mA and supply current to 400 µA during fault conditions.

Key Specifications

Pinout & Package

VIPER37HE is housed in a SO16 narrow (SO16N) surface-mount package with exposed DRAIN pins (13–16) thermally connected to the metal frame for enhanced heat dissipation. Pin 4 (N.A.) must be tied to GND for noise immunity; pins 1–2 and 9–12 are ground or no-connect as defined per layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar offline converter applications.

Compared with ICE3B0565J and LNK364PG, VIPER37HE provides higher voltage ruggedness (800 V), lower standby power (30 mW vs. ≥150 mW), and direct brownout/burst-mode configuration via dedicated pins - making it optimal for universal-input, low-noise, energy-compliant auxiliary supplies.

Availability

VIPER37HE is available at Aetrix Electronics and suitable for ATX auxiliary power supplies, white goods control boards, and consumer electronics SMPS requiring stable component supply, long-term lifecycle support, and compliance with Energy Star and EU CoC Tier 2 standards.

Supply support for VIPER37HE 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.

VIPER37HE belongs to the VIPerPlus family of integrated offline converters, engineered specifically for cost-sensitive, high-reliability AC-DC power supplies in consumer and home appliance applications where integration, safety, and energy efficiency are critical.

FAQ

What is the purpose of the BR pin on VIPER37HE?

The BR (Brownout) pin monitors rectified input voltage via a resistive divider. When voltage drops below 0.45 V (with 50 mV hysteresis), the IC shuts down non-latching to prevent unstable operation during low-line conditions. It draws only 7–12 µA and can be grounded if unused - ensuring robust input undervoltage protection without external comparators.

How does the CONT pin function in VIPER37HE?

The CONT pin serves two configurable roles: (1) adjusting cycle-by-cycle current limit by connecting an external resistor to GND, or (2) enabling overvoltage protection by monitoring output voltage via optocoupler feedback. Its dual functionality eliminates need for separate OVP circuitry and allows fine-tuning of power stage current limits without changing transformer turns ratio.

Can VIPER37HE operate without an auxiliary winding?

Yes - VIPER37HE integrates a high-voltage startup circuit powered directly from the DRAIN pin, enabling initial VDD charging without auxiliary winding. Once running, self-supply is maintained via auxiliary winding or bias winding. This feature simplifies transformer design and improves reliability in space-constrained adapters and auxiliary supplies.

What thermal management considerations apply to VIPER37HE in SO16N package?

The SO16N package uses pins 13–16 as exposed DRAIN terminals thermally connected to the metal frame. For reliable operation at full load, PCB copper area ≥100 mm² (35 µm thick) must be placed under these pins. Thermal resistance junction-to-ambient is 80 °C/W on standard FR4 - requiring heatsinking or airflow above 12 W continuous output to maintain T_J < 125 °C.