STMicroelectronics VIPER318XDTR

Overview

VIPER318XDTR from STMicroelectronics is an energy-saving offline high-voltage converter IC integrating an 800 V avalanche-rugged N-channel power MOSFET, current-mode PWM controller, embedded HV startup and sense FET, and jittered 30 kHz ±7% oscillator. It delivers up to 31 W in open-frame designs at 50°C ambient, supports flyback/buck/buck-boost topologies, and achieves <20 mW no-load input power at 230 VAC - ideal for low-power SMPS in home appliances and lighting.

For engineers reviewing the VIPER318XDTR datasheet, VIPER318XDTR pinout, VIPER318XDTR application, or VIPER318XDTR equivalent, key selection criteria include its 850 mA drain current limit (typ.), 4.5–30 V supply range, 1.2 V internal error amplifier reference, thermal shutdown at 150°C, and OVP/UVP protection with user-configurable thresholds on dedicated pins.

Technical Context

The VIPER318XDTR implements a fixed-frequency current-mode PWM controller with built-in soft-start (8 ms typ.) and pulse-skipping logic to prevent flux runaway during light-load or startup conditions. Its integrated 800 V MOSFET features 3.5 Ω R_DS(on) at 25°C and 7 Ω at 125°C, enabling ultra-wide AC input operation (85–265 VAC) without external snubber scaling.

Control architecture includes an internal transconductance error amplifier (G_M = 550 µA/V typ.) referenced to 1.2 V, a jittered oscillator (30 kHz ±7% for X-type), and dual-stage protection: auto-restart OLP/thermal/OVP and non-restart UVP/pulse-skip/disable - all implemented with dedicated pins (UVP, OVP, FB, COMP) for precise system-level regulation.

Key Specifications

Pinout & Package

Package: SO-16 narrow (SO16N), surface-mount, with DRAIN pins (13–16) thermally connected to MOSFET metal pad for enhanced heat dissipation; GND (Pin 1) serves as both MOSFET source and bias return.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICE3B0565J and VIPER22ADIP, VIPER318XDTR offers superior surge immunity (800 V), lower no-load power, integrated protections with dedicated pins, and jittered EMI reduction - making it optimal for certified, globally deployed low-power SMPS where reliability and regulatory compliance are critical.

Availability

VIPER318XDTR is available at Aetrix Electronics and suitable for home appliance power supplies, smart lighting drivers, industrial sensor interfaces, and low-power IoT adapters requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for VIPER318XDTR 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 sensing solutions for industrial, automotive, and consumer markets.

VIPER31 is part of ST's high-voltage AC-DC converter product line, engineered specifically for compact, energy-efficient offline power supplies under 31 W - emphasizing integration, safety certification readiness, and ultra-low standby power.

FAQ

What is the maximum continuous output power achievable with VIPER318XDTR in a non-ventilated adapter?

VIPER318XDTR delivers up to 27 W continuous output power in a non-ventilated enclosed adapter at 50°C ambient, as verified per STMicroelectronics' DS13285 characterization (Table 8). This rating assumes SO16N package mounted on standard FR4 with 100 mm² copper area and proper thermal layout - exceeding typical requirements for Class II-rated wall adapters.

How does the jittered oscillator reduce EMI in VIPER318XDTR-based designs?

The 30 kHz ±7% jittered oscillator spreads switching energy across a 4.2 kHz bandwidth centered at 30 kHz, lowering peak harmonic amplitudes measured with average detectors. This allows designers to meet CISPR-22/32 Class B conducted EMI limits using smaller, lower-cost Y-capacitors and common-mode chokes - validated in ST's reference design AN4729.

Can VIPER318XDTR operate without an auxiliary winding for VCC supply?

Yes - VIPER318XDTR integrates a high-voltage startup current source that charges the VCC capacitor directly from the DRAIN pin, eliminating the need for an auxiliary winding in most flyback designs. However, an auxiliary winding is required for sustained operation above ~10 W output, as the internal HV source disables once VCC reaches 8 V and the IC switches.

What is the function of the N.C. pins (2 and 9–12) on the SO16N package?

Pins 2 and 9–12 are not connected internally and must be left floating on the PCB to maintain safe creepage and clearance distances per IEC 60950-1. Pin 2 may be tied to GND for mechanical stability, but pins 9–12 must remain unconnected - doing otherwise risks violating isolation requirements and compromising safety certification.