STMicroelectronics VIPER317LDTR

Overview

VIPER317LDTR from STMicroelectronics is a high-voltage offline PWM controller IC integrating an 800 V avalanche-rugged N-channel MOSFET, current-mode control, and embedded HV startup circuitry. It delivers up to 19 W in open-frame designs at 50°C ambient, supports flyback/buck/buck-boost topologies, and features 60 kHz ±7% jittered switching frequency, 710 mA drain current limit, and <20 mW no-load consumption at 230 VAC - enabling energy-efficient low-power SMPS for lighting and home automation.

For engineers reviewing the VIPER317LDTR datasheet, VIPER317LDTR pinout, VIPER317LDTR application, or VIPER317LDTR equivalent, this device is selected for ultra-wide AC input (85–265 VAC) offline converters requiring integrated HV startup, precise OCP threshold (710 mA typ.), thermal shutdown with auto-restart, and EMI-reducing frequency jitter - all in a compact SO-16N package.

Technical Context

The VIPER317LDTR implements a current-mode PWM architecture with internal transconductance error amplifier referenced to 1.2 V, soft-start timing of 8 ms, and pulse-frequency modulation (PFM) at light load to maintain sub-20 mW no-load power. Its oscillator operates at 60 kHz ±7% with 200 Hz modulation depth, reducing conducted EMI without external spread-spectrum circuitry.

Protection logic includes auto-restart thermal shutdown (150°C threshold), overload/short-circuit protection with 50 ms delay, and separate OVP (4 V threshold) and UVP (0.4 V threshold) pins with configurable debouncing. The embedded sense-FET enables lossless current sensing, while the HV startup current source (8.8 mA typ.) charges VCC directly from DRAIN.

Key Specifications

Pinout & Package

Package: SO-16N (16-pin small outline, exposed drain pad for thermal dissipation). Pin 13–16 are internally connected to the MOSFET drain and must be soldered to large copper areas for optimal thermal performance (R_TH-JA = 85 °C/W with 100 mm² Cu).

Key Features

Applications

Equivalent & Alternatives

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

Compared with VIPER317LDTR, VIPER318LDTR offers higher power capability in identical footprint and feature set, while ICE3B0565J requires external circuitry for functions integrated into VIPER317LDTR - increasing BOM, layout complexity, and no-load power.

Availability

VIPER317LDTR is available at Aetrix Electronics and suitable for smart lighting drivers, home appliance power supplies, industrial sensor modules, and low-power AC/DC adapters requiring stable component supply, long-term lifecycle support, and compliance with global energy standards.

Supply support for VIPER317LDTR 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

VIPER31 is part of ST's high-voltage AC-DC converter product line, engineered specifically for cost-sensitive, space-constrained offline SMPS designs requiring integrated power switch, low no-load consumption, and robust protection - targeting lighting, appliances, and IoT edge devices.

FAQ

What is the maximum continuous output power achievable with VIPER317LDTR?

VIPER317LDTR delivers up to 19 W in open-frame designs at 50°C ambient temperature using flyback topology with adequate PCB copper area (100 mm²) for thermal dissipation. In enclosed non-ventilated adapters, typical continuous output is 16 W at 50°C ambient. Output power is limited by thermal constraints and the 710 mA drain current limit, not by switching frequency or voltage rating.

How does the jittered oscillator reduce EMI in practical designs?

The 60 kHz ±7% frequency jitter spreads harmonic energy across a ~8.4 kHz bandwidth (±4.2 kHz), lowering peak conducted emissions by 5–10 dB compared to fixed-frequency operation. This allows reduction of common-mode choke inductance by ~30% and X-capacitor value by ~25% while still passing CISPR 32 Class B average limits - verified in ST reference design AN4770.

Can VIPER317LDTR operate without an auxiliary winding for VCC supply?

Yes - VIPER317LDTR integrates a high-voltage startup current source that charges the VCC capacitor directly from the DRAIN pin during startup, eliminating the need for an auxiliary winding in most designs. Once running, VCC can be sustained by an auxiliary winding or, in non-isolated topologies, directly from the regulated output if ≥5 V. External startup resistors are unnecessary.

What protection features restart automatically after fault clearance?

VIPER317LDTR automatically restarts after overload/short-circuit (50 ms delay), overvoltage (500 ms restart interval), and thermal shutdown (1 s restart delay). Pulse-skip protection, undervoltage disable (UVP), and max duty-cycle limiting do not trigger auto-restart - they suspend switching until the condition clears and internal timers expire (e.g., 30 ms UVP restore delay).