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

STMicroelectronics L6566BHTR

Name: L6566BHTR
Brand: STMicroelectronics
SKU: L6566BHTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6566BHTR

Manufacturer:: STMicroelectronics

Category:: AC DC Converters, Offline Switches

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

Datasheet:: L6566BHTR.pdf

Description:: IC OFFLINE SWITCH FLYBACK 16SO

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L6566BHTR from STMicroelectronics is a multimode current-mode primary controller IC for offline flyback converters operating from rectified 3-phase mains (up to 700 V_DC). It supports both fixed-frequency (FF) and quasi-resonant (QR) operation, features an 840 V high-voltage startup pin, adaptive UVLO, pulse-by-pulse OCP with hiccup-mode saturation detection, and a ±600/+800 mA totem-pole gate driver in SO16N package - enabling high-efficiency industrial SMPS designs.

For engineers reviewing the L6566BHTR datasheet, L6566BHTR pinout, L6566BHTR application, or L6566BHTR equivalent, key selection considerations include its QR/FF mode selectability, line feedforward for constant power across input voltage range, programmable frequency modulation for EMI reduction, transformer saturation detection, and brownout protection with 0.45 V threshold.

Technical Context

The L6566BHTR implements dual-mode control logic: FF mode uses an oscillator-defined switching frequency with 70% min. duty cycle limit and slope compensation; QR mode triggers MOSFET turn-on via zero-current detection on the ZCD pin, enabling valley-switching and potential ZVS at heavy load. Its internal 1 V reference on OSC pin sets frequency via external resistor to GND.

Protection architecture includes two-level OCP: first-level uses CS pin with 150 ns leading-edge blanking and 1.5 V latch threshold for transformer saturation or secondary diode short; second-level OVP is strobed and digitally filtered on ZCD pin (5 V trip), with latched or auto-restart behavior selectable externally. Brownout is non-latched, activated at AC_OK < 0.45 V with 15 µA hysteresis current.

Key Specifications

Parameter	Value and Actual Design Meaning
Operating Modes	Fixed-frequency (FF) or quasi-resonant (QR); mode selected via MODE/SC pin connection to VREF or floating.
Startup Voltage Rating	840 V on HVS pin - enables direct connection to rectified 3-phase mains without external HV resistor network.
Gate Driver Output	±600/+800 mA totem-pole output with active pull-down during UVLO - drives MOSFETs/IGBTs directly with robust noise immunity.
Quiescent Current	< 3 mA - enables compliance with energy-saving standards during light-load burst-mode operation.
Line Feedforward Range	0–3 V on VFF pin - linearly scales current-sense threshold to maintain constant output power across 300–700 V_DC input.
OCP Threshold Accuracy	CS pin comparator reference: 0.450 V (primary) and 1.5 V (saturation latch) - ensures precise overcurrent response and fault isolation.
Brownout Threshold	0.45 V on AC_OK pin with 15 µA hysteresis - provides fast, non-latched shutdown under low-input-voltage conditions.

Pinout & Package

Package: SO16N - 16-pin small-outline integrated circuit with standard 1.27 mm pitch, creepage-optimized layout for high-voltage isolation, and thermal pad not present (standard plastic body).

Pin/Terminal	Circuit Role	Design Meaning
1 HVS	High-voltage startup input	Withstands 840 V; internal 1 mA current source charges VCC capacitor until UVLO turn-on threshold is reached.
3 GND	Signal and gate-drive return	Common ground for all analog circuitry and totem-pole driver; must be star-connected to minimize noise coupling.
4 GD	Gate driver output	Drives external MOSFET/IGBT gate; ±600/+800 mA peak drive with active pull-down during UVLO.
5 VCC	Internal supply rail	Powered by HVS startup or auxiliary winding; UVLO thresholds adapt dynamically (5.7 V turn-on, ~4.5 V shutdown).
7 CS	Current sense input	Accepts shunt voltage; 150 ns blanking, 0.450 V primary OCP, 1.5 V saturation latch - enables robust primary-side sensing.
9 COMP	Control loop feedback input	Optocoupler-driven node; 2.5–5 V dynamic range; bottom-clamped at ~2 V; <1.4 V forces shutdown.
11 ZCD	Zero-current detection / OVP input	Triggers QR turn-on on negative edge; >5 V causes OVP shutdown - strobed and digitally filtered for noise immunity.
12 MODE/SC	Mode selection / slope compensation	Tied to VREF → QR mode; floating → FF mode; also used for FF slope compensation when connected to CS via resistor.
13 OSC	Oscillator reference	1 V accurate source; external R-to-GND sets max. frequency (QR) or operating frequency (FF).
14 SS	Soft-start / fault delay	Internal current charges external capacitor; controls ramp-up of CS clamp and delays OLP shutdown.
15 VFF	Line voltage feedforward	0–3 V input scales OCP threshold inversely with input voltage - maintains constant power across wide mains range.
16 AC_OK	Brownout detection	0.45 V threshold with 15 µA hysteresis - non-latched shutdown; clears latches from DIS, SS, or VFF faults.

Key Features

Feature	Design Value
Adaptive UVLO	UVLO turn-on threshold dynamically lowered at light load to counteract self-supply voltage drop caused by transformer parasitics.
Valley-skipping in QR mode	Prevents excessive frequency rise at medium/light load by skipping demagnetization valleys - preserves ZVS capability and EMI performance.
Programmable frequency modulation	FMOD pin accepts RC network to generate triangular waveform; modulates OSC current to spread switching spectrum and reduce peak EMI.
Transformer saturation detection	Dual-threshold CS comparator (0.45 V + 1.5 V) distinguishes normal overload from core saturation - prevents destructive secondary faults.
Latched disable input (DIS)	4.5 V threshold on DIS pin enables external OTP implementation using NTC thermistor - latches off IC until power recycle.

Applications

Industrial 3-Phase SMPS

Single-Stage PFC Flyback

Use Scenario: 1 kW industrial power supply fed from rectified 3-phase 400 VAC mains, requiring high efficiency and EN61000-3-2 compliance.

IC Role / Device Role / Timing Role: Primary-side current-mode controller managing QR flyback operation with line feedforward and adaptive UVLO.

Use Value: Enables >90% efficiency at full load and <300 mW no-load consumption via burst-mode and low quiescent current.

Use Scenario: Single-stage AC-DC converter for LED drivers or telecom adapters where input-current shaping meets JEITA-MITI harmonic limits.

IC Role / Device Role / Timing Role: Dual-function controller executing input-current shaping and output regulation in one stage using FF mode and VFF scaling.

Use Value: Eliminates separate PFC stage while maintaining THD <10% and power factor >0.95 across universal input range.

High-Voltage Rectified Input Systems

Energy-Efficient Industrial Adapters

Use Scenario: Off-line power supply for motor drives or PLCs accepting 500–700 VDC input from unregulated 3-phase rectification.

IC Role / Device Role / Timing Role: High-voltage startup-capable controller with 840 V HVS pin and brownout protection at 0.45 V on AC_OK.

Use Value: Removes need for external HV startup circuitry, reduces BOM cost, and ensures reliable start-up even after deep discharge events.

Use Scenario: DIN-rail mounted 24 V/20 A industrial adapter requiring no-load power <150 mW and Class II isolation.

IC Role / Device Role / Timing Role: Burst-mode controller with adaptive UVLO and soft-start, coordinating gate drive timing and OCP response.

Use Value: Achieves ERP Tier 2 standby compliance via controlled burst frequency, low I_Q, and programmable soft-start delay.

Equivalent & Alternatives

The following parts are listed as comparable options for similar multimode flyback controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
UCC28064DR	Fixed-frequency only; no QR mode or ZCD input; 650 V max startup; no adaptive UVLO.	Suitable for cost-sensitive single-phase SMPS but cannot replace L6566BHTR in 3-phase or ZVS-critical QR designs.	Select only if QR operation and 840 V startup are unnecessary; verify VFF and brownout functions are implemented externally.
ICE2QS03G	QR-only controller; no FF mode; lower HV startup rating (650 V); no line feedforward or programmable FMOD.	Applicable to light-load optimized QR flybacks but lacks constant-power capability and EMI spread-spectrum features.	Choose only for QR-focused designs with ≤650 V input; confirm missing VFF and brownout functions are handled in system design.

Compared with UCC28064DR and ICE2QS03G, the L6566BHTR uniquely combines 3-phase-compatible 840 V startup, dual FF/QR mode selectability, line feedforward for constant power, and integrated brownout - making it irreplaceable in high-reliability industrial flyback systems demanding wide input range and regulatory compliance.

Availability

L6566BHTR is available at Aetrix Electronics and suitable for industrial SMPS, 3-phase offline converters, and single-stage PFC applications requiring stable component supply, long-term lifecycle support, and traceable sourcing for safety-critical deployments.

Supply support for L6566BHTR 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, specializing in power management, analog, MCU, and automotive ICs with strong industrial and energy infrastructure focus.

The L6566BHTR belongs to ST's high-voltage AC-DC controller product line, engineered specifically for robust, high-efficiency flyback converters operating from rectified 3-phase mains and demanding compliance with international energy and harmonic standards.

FAQ

What is the purpose of the MODE/SC pin, and how does it affect operation?

The MODE/SC pin selects between fixed-frequency (FF) and quasi-resonant (QR) operation: tying it to VREF enables QR mode, where ZCD triggers MOSFET turn-on at transformer demagnetization valleys; leaving it floating selects FF mode, where OSC sets the switching frequency and the pin outputs a synchronized ramp for slope compensation. In FF mode, connecting MODE/SC to CS via a resistor injects slope compensation to prevent subharmonic oscillation.

How does the adaptive UVLO function improve reliability in high-voltage flyback designs?

The adaptive UVLO dynamically lowers the VCC turn-off threshold at light load to compensate for voltage droop caused by transformer leakage inductance and winding resistance - preventing premature shutdown during burst-mode operation. This ensures continuous regulation down to no-load conditions while maintaining safe restart margins, especially critical in 3-phase rectified systems with high self-supply impedance.

Can the L6566BHTR be used in single-phase applications, and what modifications are needed?

Yes - the L6566BHTR is fully compatible with single-phase rectified inputs (e.g., 340 VDC). No circuit modifications are required; simply scale the VFF resistor divider for the lower input voltage range and adjust the ZCD divider to maintain proper demagnetization detection margin. All protections, startup, and control features operate identically, making it suitable for universal-input designs.

What is the role of the FMOD pin, and how is EMI reduction achieved?

The FMOD pin enables frequency modulation by generating a triangular waveform that modulates the current sourced from the OSC pin, thereby varying the switching frequency around a center value. This spread-spectrum technique distributes energy across a wider bandwidth, reducing peak EMI amplitudes by up to 10 dB - critical for passing CISPR-22/32 Class B conducted emissions without adding costly filtering components.

L6566BHTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Output Isolation:: Isolated

Internal Switch(s):: No

Voltage - Breakdown:: -

Topology:: Flyback

Voltage - Start Up:: 14 V

Voltage - Supply (Vcc/Vdd):: 8V ~ 23V

Duty Cycle:: 75%

Frequency - Switching:: 10kHz ~ 300kHz

Power (Watts):: -

Fault Protection:: Current Limiting, Over Load

Control Features:: Soft Start

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

Grade:: -

Qualification:: -

Supplier Device Package:: 16-SO

Mounting Type:: Surface Mount

L6566BHTR FAQ

1.How can I place an order for L6566BHTR through Aetrix?

Please submit a Request for Quotation (RFQ) for L6566BHTR 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 L6566BHTR reliable?

The price and inventory of L6566BHTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6566BHTR is usually 5 days.

3.What payment methods are accepted for L6566BHTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6566BHTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6566BHTR?

L6566BHTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6566BHTR 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 L6566BHTR?

For technical support, including L6566BHTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6566BHTR requirements.

6.How does Aetrix verify that L6566BHTR is sourced from the original manufacturer or authorized distributors?

All L6566BHTR 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 L6566BHTR meets industry standards.

7.What is the process for return or replacement of L6566BHTR?

All L6566BHTR units undergo pre-shipment inspection (PSI). If there is an issue with L6566BHTR, 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 L6566BHTR part is unused and in its original packaging.

Return procedure for L6566BHTR:

1.Submit a request within 90 days.

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

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