STMicroelectronics VIPER28LD

Overview

VIPER28LD 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 12 W continuous power (85–265 VAC), supports 115 kHz switching (H-type), and achieves 30 mW no-load consumption at 230 VAC - enabling compliance with stringent energy-saving standards in auxiliary power supplies.

For engineers reviewing the VIPER28LD datasheet, VIPER28LD pinout, VIPER28LD application, or VIPER28LD equivalent, key selection considerations include its dual-level overcurrent protection (IDlim = 0.8 A typ., IDMAX = 1.2 A), adjustable extra power timer (EPT), digital OVP with 3.0 V threshold ±10%, and SO16 narrow package thermal resistance of 105 °C/W (junction-to-ambient).

Technical Context

The VIPER28LD implements a jittered oscillator (±4 kHz modulation depth at 115 kHz) to reduce EMI, and integrates a dedicated SenseFET for lossless current sensing. Its current-mode control uses cycle-by-cycle peak current limiting set via the CONT pin, with soft-start (8.5 ms typ.) and leading-edge blanking (300 ns) to suppress noise-induced false triggering.

Burst-mode operation activates below 0.6 V on FB (VFBbm = 0.6 V typ.), reducing standby consumption; overload protection includes strobed digital OVP (2.2 µs response) and thermal shutdown at 155 °C with 30 °C hysteresis. The IC auto-restarts after fault clearance with low repetition rate to prevent thermal runaway.

Key Specifications

Pinout & Package

Package: SO16 narrow (SOIC-16, 3.9 mm width), optimized for surface-mount assembly and thermal dissipation via exposed DRAIN pins (pins 13–16) connected to PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage AC-DC converter applications.

Compared with VIPER27LD and ICE3B0565J, VIPER28LD offers superior surge robustness (800 V), lower no-load power, and unique EPT functionality - making it optimal for compact, high-reliability auxiliary supplies demanding extended overload capability without secondary-side complexity.

Availability

VIPER28LD is available at Aetrix Electronics and suitable for smart meter auxiliary supplies, home appliance standby PSUs, and compact AC-DC adapters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for VIPER28LD 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 sensor solutions for industrial, automotive, and consumer markets.

VIPER28LD belongs to the VIPer Plus family of high-voltage converters engineered for ultra-low standby power and minimal external component count in universal-input AC-DC applications.

FAQ

What is the maximum continuous output power achievable with VIPER28LD in an open-frame design?

VIPER28LD delivers up to 12 W continuous output power at 50 °C ambient in an open-frame configuration with adequate PCB copper pour under DRAIN pins. This assumes 85–265 VAC input, 115 kHz operation, and proper thermal management per SO16 narrow package RthJA = 105 °C/W specification.

How does the EPT (Extra Power Timer) function protect the system during overload?

The EPT pin accepts an external capacitor that sets a programmable delay (typically 2–5 seconds) before entering hiccup mode during overload. During this interval, the IC sustains elevated output current without immediate shutdown, allowing brief peak loads like motor startup or firmware update bursts to complete safely.

Can VIPER28LD operate without an auxiliary winding on the transformer?

Yes - VIPER28LD integrates a high-voltage startup generator powered directly from the DRAIN pin, eliminating the need for an auxiliary winding. The HV current source charges the VDD capacitor during startup, enabling single-winding transformer designs and reducing component count.

What is the purpose of the N.A. pin (pin 4) in the SO16 narrow package?

Pin 4 (N.A.) is mechanically bonded to the controller die pad and serves as a thermal and noise-immunity enhancement point. Though not user-accessible for signal routing, STMicroelectronics recommends connecting it to GND to improve EMI rejection and provide an additional thermal conduction path from the die to the PCB.