STMicroelectronics VIPER15LDTR

Overview

VIPER15LDTR from STMicroelectronics is an off-line high-voltage QR flyback controller IC with integrated 800 V avalanche-rugged N-channel MOSFET, quasi-resonant valley switching, <50 mW standby power at 265 Vac, adjustable current limit via ZCD pin, and on-board soft-start. It targets auxiliary and main SMPS in LCD TVs, LED drivers, set-top boxes, and utility meters.

For engineers reviewing the VIPER15LDTR datasheet, VIPER15LDTR pinout, VIPER15LDTR application, or VIPER15LDTR equivalent, this page delivers verified technical context, real-world design meanings for key specs, SO-16 narrow package layout, functional alternatives with documented differences, and supply support for industrial embedded and connected-device programs.

Technical Context

The device integrates a high-voltage startup generator drawing current directly from the DRAIN pin, enabling self-biasing without external HV resistor networks. Its ZCD pin performs zero-current detection for QR operation, sets drain current limit via RLIM resistor, enables voltage feed-forward via RFF, and implements strobed overvoltage protection with 2.2 µs digital filtering.

Control logic includes burst-mode operation below 0.45 V FB input, frequency foldback down to 1/64 of nominal (≤2.3 kHz for VIPER15L), dual OCP (primary 0.4 A, secondary 0.6 A), brown-out detection with 50 mV hysteresis, and hysteretic thermal shutdown at 155 °C with 30 °C hysteresis.

Key Specifications

Pinout & Package

VIPER15LDTR uses the SO-16 narrow (SO16N) surface-mount package with exposed drain pads (pins 13–16) thermally connected to the metal frame for enhanced heat dissipation. Pin 4 (N.A.) is internally unused and may be tied to GND or left floating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar off-line QR flyback controller applications.

Compared with ICE2QS03G and LNK364PG, VIPER15LDTR provides higher voltage ruggedness (800 V), true QR valley switching without external timing components, and unified ZCD functionality for current limit, feed-forward, and OVP-enabling simpler, more efficient, and lower-noise offline SMPS designs.

Availability

VIPER15LDTR is available at Aetrix Electronics and suitable for auxiliary power supplies in LCD TVs, LED drivers, set-top boxes, and utility power meters requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for VIPER15LDTR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

VIPER15LDTR belongs to the VIPerPlus family of high-voltage off-line controllers, engineered specifically for cost-sensitive, compact, and energy-efficient AC-DC conversion in consumer and industrial auxiliary power applications.

FAQ

What is the purpose of the ZCD pin on VIPER15LDTR?

The ZCD pin serves four critical functions: (1) zero-current detection for quasi-resonant valley switching, (2) setting primary current limit via RLIM resistor to ground, (3) enabling input voltage feed-forward via RFF resistor to auxiliary winding, and (4) triggering overvoltage protection when voltage exceeds 4.2 V. Its multi-function architecture eliminates external comparators and sensing resistors.

How does VIPER15LDTR achieve <50 mW standby power?

VIPER15LDTR achieves sub-50 mW standby power through burst-mode operation triggered below 0.45 V on the FB pin, reducing average switching frequency to ~2 kHz, combined with ultra-low quiescent current (270 µA when VDD < 8.5 V) and integrated HV startup that disables after initial charge-eliminating continuous HV resistor losses.

Can VIPER15LDTR replace VIPER12LDTR in an existing design?

No-VIPER15LDTR has higher power capability (10 W open-frame vs. 6 W for VIPER12), different soft-start time (3.5 ms vs. 2.5 ms), and distinct oscillator frequency range (122–150 kHz vs. 90–110 kHz). Layout, transformer turns ratio, and ZCD/FB compensation must be re-validated; direct replacement risks instability or overstress.

What thermal derating applies to VIPER15LDTR in SO-16 narrow package?

In SO-16 narrow package, VIPER15LDTR has R_thJA = 90 °C/W on standard FR4 (100 mm² copper) and R_thJP = 35 °C/W to drain pins. At 1 W dissipation, junction temperature rise is 90 °C above ambient-so maximum ambient must be limited to 60 °C for safe 150 °C T_J operation. Exposed drain pads must be soldered to ≥200 mm² thermal pad for full rating.