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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > AC DC Converters, Offline Switches

STMicroelectronics VIPER318LDTR

Name: VIPER318LDTR
Brand: STMicroelectronics
SKU: VIPER318LDTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: VIPER318LDTR

Manufacturer:: STMicroelectronics

Category:: AC DC Converters, Offline Switches

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: VIPER318LDTR.pdf

Description:: IC OFFLINE SWITCH MULT TOP 16SO

Quantity:: RFQ Add To RFQ list

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Inventory:1,795

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Product details

Overview

VIPER318LDTR from STMicroelectronics is an 800 V avalanche-rugged offline high-voltage PWM converter IC integrating a power MOSFET, HV startup circuit, current-sense FET, error amplifier, and jittered oscillator. It delivers up to 31 W in open-frame designs at 50°C ambient, supports flyback/buck/buck-boost topologies, and features 850 mA drain current limit, 60 kHz ±7% switching frequency, and 1.2 V internal reference for feedback control - used in low-power SMPS for home appliances and industrial controls.

For engineers reviewing the VIPER318LDTR datasheet, VIPER318LDTR pinout, VIPER318LDTR application, or VIPER318LDTR equivalent, key selection criteria include its 800 V MOSFET breakdown rating, 60 kHz jittered oscillator, 850 mA OCP threshold, UVP/OVP programmable protection pins, and SO-16N package thermal performance (R_TH-JA = 85 °C/W with 100 mm² copper).

Technical Context

The VIPER318LDTR implements current-mode PWM control with integrated transconductance error amplifier referenced to 1.2 V, enabling primary-side regulation via direct FB feedback or secondary-side optocoupler-driven COMP. Its HV startup circuit delivers 8.8 mA typ. charging current to VCC at 100 V DRAIN, reducing no-load consumption to <20 mW @230 VAC.

Protection architecture includes auto-restart OLP/thermal shutdown/OVP (4 V threshold, 500 ms restart) and non-restart pulse-skip (to prevent flux runaway), UVP disable (0.4 V threshold, 30 ms debounce), and soft-start (8 ms). The 60 kHz ±7% jittered oscillator reduces EMI filter cost by spreading harmonic energy across ±14 kHz bandwidth at 200 Hz modulation rate.

Key Specifications

Parameter	Value and Actual Design Meaning
Drain Voltage Rating	800 V - enables ultra-wide AC input range (85–265 VAC) and reduces snubber size
OCP Threshold	850 mA typ. - sets peak current limit for flyback/buck power stage design
Switching Frequency	60 kHz ±7% - jittered spread-spectrum operation lowers conducted EMI and filter cost
VCC Operating Range	4.5–30 V - supports auxiliary winding or output-derived bias with UVLO (4.25 V) and overvoltage clamp
Reference Voltage	1.2 V typ. - precision internal reference for FB-based voltage regulation loop
Thermal Shutdown	160 °C typ. - protects MOSFET junction during overload or poor heatsinking
No-Load Consumption	<20 mW @230 VAC - meets stringent energy-saving standards (e.g., EU CoC Tier 2)
Package Thermal Resistance	R_TH-JA = 85 °C/W - achieved with 100 mm² PCB copper area, enabling 31 W open-frame operation

Pinout & Package

The VIPER318LDTR is housed in a SO-16N (Small Outline, 16-pin, narrow) package with exposed drain pads (pins 13–16) for enhanced thermal dissipation. Pin 1 is GND; pins 2, 4, and 9–12 are NC/N.A.; pins 13–16 are internally connected to the MOSFET drain and must be soldered to large copper pour for thermal management.

Pin/Terminal	Circuit Role	Design Meaning
1 GND	Ground reference and MOSFET source	Return path for bias currents and MOSFET source; must be isolated from pulsed return paths
3 VCC	Controller supply input	Charged by HV startup current source; requires ≥10 µF storage cap + 0.1 µF bypass
5 UVP	Undervoltage/disable input	0.4 V threshold disables IC with ultra-low residual consumption; debounced 30 ms
6 OVP	Overvoltage protection input	4 V threshold triggers auto-restart OVP; 250 µs debounce prevents false triggering
7 FB	Inverting input of error amplifier	1.2 V reference node; accepts direct output voltage divider or optocoupler feedback
8 COMP	Error amplifier output	Drives current-limit setpoint; compensation network placed between COMP and GND
13–16 DRAIN	MOSFET drain terminals	High-voltage switching node; mechanically tied to MOSFET die pad for thermal conduction

Key Features

Feature	Design Value
Integrated 800 V avalanche-rugged MOSFET	Eliminates external HV switch and reduces BOM count in offline converters
Embedded HV startup current source	Delivers 8.8 mA typ. to charge VCC capacitor directly from DRAIN, removing startup resistor
Jittered 60 kHz oscillator	±7% frequency spread at 200 Hz lowers EMI peak amplitudes, enabling smaller input filters
Programmable UVP/OVP pins	Separate 0.4 V UVP and 4 V OVP thresholds allow topology-specific protection tuning
Soft-start with 8 ms ramp	Gradually increases current limit to reduce inrush stress on transformer and output caps
Pulse-skip protection	Prevents flux runaway during light-load or startup by skipping cycles when t_ON-MIN is violated

Applications

Home Appliance Power Supply

Industrial Sensor Node PSU

Use Scenario: Standby and main power supply for washing machine control board operating from 230 VAC mains.

IC Role / Device Role / Timing Role: Primary-side flyback controller providing regulated 12 V and 3.3 V rails with integrated MOSFET switching.

Use Value: 800 V rating accommodates line surges; <20 mW no-load consumption meets IEC 62301 standby power limits.

Use Scenario: Compact 5 V/1 A isolated power supply for wireless temperature sensor node in factory automation.

IC Role / Device Role / Timing Role: Flyback controller with primary-side regulation, eliminating optocoupler and TL431.

Use Value: 60 kHz jittered switching reduces EMI filtering requirements in space-constrained enclosures.

LED Driver for Smart Lighting

Low-Power AC/DC Adapter

Use Scenario: Constant-voltage LED driver for dimmable smart bulb with TRIAC phase-cut compatibility.

IC Role / Device Role / Timing Role: Buck-boost topology controller regulating output despite wide input variation from phase-cut dimmers.

Use Value: Wide 4.5–30 V VCC range allows stable operation across dimmer conduction angles; UVP pin disables output below safe input level.

Use Scenario: 12 V/0.5 A wall adapter for IoT gateway requiring CE/EN55032 Class B compliance.

IC Role / Device Role / Timing Role: Flyback controller with integrated 800 V MOSFET and jittered oscillator for EMI reduction.

Use Value: SO-16N package with 85 °C/W R_TH-JA enables 19 W continuous output without heatsink in open-frame layout.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
VIPER317LDTR	710 mA OCP, same 60 kHz frequency, identical SO-16N package	Lower max. output power (27 W vs. 31 W open-frame); suitable for ≤15 W adapters	Select when lower peak current and reduced thermal load suffice for target power level
VIPER319LDTR	990 mA OCP, same 60 kHz frequency, identical SO-16N package	Higher max. output power (35 W open-frame); requires larger transformer and snubber	Select when >31 W continuous output or higher surge tolerance is required

Compared with VIPER317LDTR and VIPER319LDTR, the VIPER318LDTR offers balanced OCP (850 mA) and thermal capability for mid-range 16–31 W applications - avoiding underdesign risk of the 317 while minimizing component stress versus the 319.

Availability

VIPER318LDTR is available at Aetrix Electronics and suitable for home appliance power supplies, industrial sensor node PSUs, and low-power AC/DC adapters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for VIPER318LDTR 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 microcontrollers, power ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The VIPER™ family is ST's dedicated line of high-voltage offline AC/DC converters targeting low-to-mid power SMPS designs where integration, efficiency, and EMI performance are critical - especially in energy-sensitive home and industrial applications.

FAQ

What is the purpose of the UVP pin on VIPER318LDTR?

The UVP (Undervoltage Protection) pin disables the IC when its voltage falls below 0.4 V for more than 30 ms, reducing residual input power to <0.35 mA. It serves dual roles: input undervoltage detection or system-level disable signal. If unused, it must be left floating; connecting it to GND or VCC will cause malfunction.

Can VIPER318LDTR operate in buck topology with 230 VAC input?

Yes - the VIPER318LDTR supports buck topology per its datasheet, but only in non-isolated configurations where output voltage is less than input. With 230 VAC (325 V_PK), output must remain ≤30 V due to VCC operating limit (30.5 V), and DRAIN voltage stress must stay within 800 V rating using proper clamping. Output regulation relies on FB feedback to the 1.2 V reference.

How does the jittered oscillator reduce EMI in VIPER318LDTR?

The 60 kHz oscillator modulates ±7% (±4.2 kHz) at 200 Hz, spreading switching harmonics across a wider bandwidth. This lowers peak amplitude in EMI receivers using average detection - allowing smaller common-mode chokes and X-capacitors. Measured conducted emissions drop by 6–10 dB compared to fixed-frequency operation.

What thermal derating applies to VIPER318LDTR in SO-16N package?

With 100 mm² of 35 µm copper on a single-sided FR4 board, R_TH-JA = 85 °C/W enables 31 W continuous output at 50°C ambient. Above 50°C, output power must be linearly derated: at 70°C ambient, max. power drops to ~24 W. Pins 13–16 must connect to copper pour; NC pins (2,4,9–12) should be grounded for noise immunity.

VIPER318LDTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: VIPER™

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Isolation:: Non-Isolated

Internal Switch(s):: Yes

Voltage - Breakdown:: 800V

Topology:: Boost, Buck, Buck-Boost, Flyback

Voltage - Start Up:: 8 V

Voltage - Supply (Vcc/Vdd):: 4.5V ~ 30V

Duty Cycle:: -

Frequency - Switching:: 132kHz

Power (Watts):: 1 W

Fault Protection:: Over Load, Over Power, Over Temperature, Over Voltage, Short Circuit

Control Features:: Soft Start

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Supplier Device Package:: 16-SO

Mounting Type:: Surface Mount

VIPER318LDTR FAQ

1.How can I place an order for VIPER318LDTR through Aetrix?

Please submit a Request for Quotation (RFQ) for VIPER318LDTR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for VIPER318LDTR reliable?

The price and inventory of VIPER318LDTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for VIPER318LDTR is usually 5 days.

3.What payment methods are accepted for VIPER318LDTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for VIPER318LDTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for VIPER318LDTR?

VIPER318LDTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your VIPER318LDTR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for VIPER318LDTR?

For technical support, including VIPER318LDTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your VIPER318LDTR requirements.

6.How does Aetrix verify that VIPER318LDTR is sourced from the original manufacturer or authorized distributors?

All VIPER318LDTR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that VIPER318LDTR meets industry standards.

7.What is the process for return or replacement of VIPER318LDTR?

All VIPER318LDTR units undergo pre-shipment inspection (PSI). If there is an issue with VIPER318LDTR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The VIPER318LDTR part is unused and in its original packaging.

Return procedure for VIPER318LDTR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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