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

STMicroelectronics L6565N

Name: L6565N
Brand: STMicroelectronics
SKU: L6565N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6565N

Manufacturer:: STMicroelectronics

Category:: AC DC Converters, Offline Switches

Package:: 8-DIP (0.300", 7.62mm)

Datasheet:: L6565N.pdf

Description:: IC OFFLINE SWITCH FLYBACK 8DIP

Quantity:: RFQ Add To RFQ list

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Inventory:1,274

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Product details

Overview

L6565N from STMicroelectronics is a current-mode quasi-resonant (QR) zero-voltage-switching (ZVS) flyback controller IC for offline AC-DC power supplies. It features line voltage feedforward for constant power delivery across 88–264 VAC mains, frequency foldback for <3.5 mA quiescent current at light load, and ±400 mA totem-pole gate drive. Used in 50 W TV SMPS and 40 W inkjet printer adapters compliant with Blue Angel and Energy Star.

For engineers reviewing the L6565N datasheet, L6565N pinout, L6565N application, or L6565N equivalent, key selection criteria include ZCD-triggered QR timing accuracy, VFF-based pulse-by-pulse OCP scaling, hiccup-mode OCP response to secondary diode failure, and 1% internal 2.5 V reference stability over −40°C to 125°C junction temperature.

Technical Context

The L6565N implements QR control via transformer demagnetization sensing at ZCD (Pin 5), requiring a positive-going edge >2.1 V to arm and a negative-going edge <1.6 V to trigger MOSFET turn-on. Blanking time (3.5–18 µs) is dynamically controlled by COMP voltage to enforce minimum off-time and enable frequency foldback.

Line feedforward operates through VFF (Pin 3), scaling the current-sense clamp voltage (VCSx) from 1.4 V at 0 V VFF down to 0.2 V at 3 V VFF - enabling constant output power across universal input voltage. The error amplifier uses an internal 2.5 V ±1% reference and supports both primary regulation (via auxiliary winding divider) and secondary feedback (via optocoupler-driven COMP).

Key Specifications

Parameter	Value and Actual Design Meaning
V_REF	2.5 V ±1% @ T_j = 25°C - enables ±1% output voltage regulation in primary-feedback designs
I_START-UP	<70 µA - allows high-value start-up resistor (e.g., 3 MΩ) without compromising turn-on speed
I_Q (active)	<3.5 mA - sustains Energy Star standby compliance under light-load conditions
f_SW foldback	Dynamic blanking (3.5–18 µs) - prevents excessive switching frequency and EMI at low load
OCP type	Pulse-by-pulse + hiccup-mode - protects against sustained short-circuit on secondary rectifier
Gate drive	±400 mA peak - directly drives STP7NB80FI/STP4NA80FP MOSFETs without external buffer
V_CC UVLO	12.5–14.5 V ON / 8.7–10.3 V OFF - ensures reliable restart after brownout or capacitor discharge

Pinout & Package

DIP8 (Minidip) package with 2.54 mm pitch, 100 °C/W junction-to-ambient thermal resistance, and through-hole mounting compatibility.

Pin/Terminal	Circuit Role	Design Meaning
1 INV	Inverting input of error amplifier	Accepts voltage divider from auxiliary winding (primary feedback) or optocoupler emitter (secondary feedback); grounded when optocoupler drives COMP directly
2 COMP	Error amplifier output	Drives compensation network to INV or receives optocoupler collector current; clamped at 2.25–5.5 V to limit duty cycle range
3 VFF	Line voltage feedforward input	Scales current-limit threshold inversely with input voltage; grounding fixes OCP at max 1.4 V
4 CS	Current sense comparator input	Compares sensed primary current against VFF-scaled reference; >2 V triggers hiccup-mode OCP
5 ZCD	Zero-current detection / sync input	Armed by >2.1 V, triggered by <1.6 V falling edge; also serves as disable input when pulled <150 mV
6 GND	Signal and gate driver return	Common reference for all analog blocks and 400 mA totem-pole driver; must be low-inductance connection
7 GD	Gate driver output	Drives MOSFET gate directly; includes UVLO pull-down to prevent spurious turn-on during startup
8 V_CC	Supply input	Powered via start-up resistor from bulk cap; regulated internally to 7 V rail; powers all circuitry except gate driver

Key Features

Feature	Design Value
Quasi-resonant ZVS control	Reduces MOSFET switching losses by synchronizing turn-on to transformer demagnetization zero-crossing
Line feedforward compensation	Maintains constant output power across 88–264 VAC input by scaling OCP threshold with V_IN
Frequency foldback	Extends light-load efficiency by reducing f_SW while preserving ZVS operation via dynamic ZCD blanking
Hiccup-mode OCP	Shuts down gate drive on sustained overcurrent (>2 V at CS), then auto-restarts after V_CC discharge below UVLO
Ultra-low quiescent current	2.3–3.5 mA operating current enables <300 mW no-load consumption in 50 W TV SMPS

Applications

TV/Monitor SMPS

AC-DC Adapters/Chargers

Use Scenario: 50 W offline flyback converter for 14" LCD TV with universal 88–264 VAC input.

IC Role / Device Role / Timing Role: Primary-side QR controller managing ZVS timing via ZCD, regulating output via auxiliary winding feedback to INV, and scaling OCP with VFF.

Use Value: Achieves >85% full-load efficiency and <300 mW no-load consumption, meeting Blue Angel requirements.

Use Scenario: 40 W inkjet printer power supply with wide-input range and burst-mode standby.

IC Role / Device Role / Timing Role: QR controller using frequency foldback and hiccup-mode OCP to maintain regulation during variable print-head load transients.

Use Value: Enables stable 12 V/1.5 A and 5 V/0.5 A outputs with <0.5% cross-regulation drift across line/load.

Digital Consumer Electronics

Printers/Fax Machines

Use Scenario: Compact set-top box power supply requiring low EMI and fast transient response.

IC Role / Device Role / Timing Role: Current-mode QR controller using COMP-driven loop compensation and VFF feedforward to suppress input ripple propagation.

Use Value: Reduces conducted EMI by 8 dBµV at 150 kHz due to ZVS soft-switching and fixed-frequency-like spectral spreading.

Use Scenario: Fax machine SMPS with dual outputs (24 V logic, 48 V thermal head) and thermal derating.

IC Role / Device Role / Timing Role: Primary controller implementing hiccup-mode OCP to survive repeated paper-jam overloads on 48 V rail.

Use Value: Prevents MOSFET thermal runaway during 5 s continuous short-circuit on secondary rectifier.

Equivalent & Alternatives

The following parts are listed as comparable options for similar quasi-resonant flyback controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
UCC28600DR	Fixed 65 kHz maximum frequency; no VFF pin; uses internal V_REF for OCP scaling	Requires external feedforward network for constant-power operation across wide input range	Select when design prioritizes predictable EMI profile over universal-input power consistency
ICE2QS03G	Integrated 650 V MOSFET; no ZCD pin; uses valley-switching detection via V_DS sensing	Eliminates external high-voltage snubber but requires drain-sense layout; no line feedforward	Select for cost-sensitive, space-constrained adapters where primary-side sensing suffices

Compared with UCC28600DR and ICE2QS03G, the L6565N uniquely combines dedicated ZCD triggering, analog VFF scaling, and hiccup-mode OCP in a discrete-controller format-enabling precise QR timing, universal-input constant power, and robust fault recovery without integrated FET trade-offs.

Availability

L6565N is available at Aetrix Electronics and suitable for TV/Monitor SMPS, AC-DC adapters/chargers, and digital consumer electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L6565N 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 sensor solutions for industrial, automotive, and consumer markets.

The L6565N belongs to ST's high-efficiency AC-DC controller product line, engineered specifically for quasi-resonant flyback topologies targeting Energy Star, Blue Angel, and ENERGY 2000 compliance in universal-input offline power supplies.

FAQ

What is the purpose of the VFF pin on the L6565N?

The VFF (Voltage FeedForward) pin scales the current-sense comparator's reference voltage inversely with input line voltage. As mains voltage rises, the OCP threshold decreases proportionally - maintaining constant output power across 88–264 VAC. Grounding VFF disables this function and fixes OCP at 1.4 V, suitable for narrow-input applications.

How does the L6565N achieve zero-voltage switching?

The L6565N detects transformer demagnetization via the ZCD pin: a positive-going edge >2.1 V arms the circuit, and a subsequent negative-going edge <1.6 V triggers MOSFET turn-on precisely at the valley of the resonant drain waveform. Internal blanking (≥3.5 µs) prevents false triggering from leakage inductance ringing.

What happens during hiccup-mode overcurrent protection?

When the CS pin exceeds 2.0 V, the gate driver disables immediately. The IC remains powered but draws only ~2 mA quiescent current. V_CC discharges through the start-up resistor until it falls below the UVLO turn-off threshold (~9.5 V), triggering automatic restart after ~400 µs timer delay - cycling until fault clears.

Can the L6565N operate without an optocoupler?

Yes - the L6565N supports primary-side regulation using a resistor divider from the transformer auxiliary winding to the INV pin. This eliminates the optocoupler and TL431, reducing BOM cost and improving reliability, while maintaining ±3% output regulation across line/load/temperature per typical application circuits.

L6565N Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Output Isolation:: Isolated

Internal Switch(s):: No

Voltage - Breakdown:: -

Topology:: Flyback

Voltage - Start Up:: 13.5 V

Voltage - Supply (Vcc/Vdd):: 10.3V ~ 18V

Duty Cycle:: -

Frequency - Switching:: -

Power (Watts):: -

Fault Protection:: Current Limiting

Control Features:: -

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

Grade:: -

Qualification:: -

Supplier Device Package:: 8-DIP

Mounting Type:: Through Hole

L6565N FAQ

1.How can I place an order for L6565N through Aetrix?

Please submit a Request for Quotation (RFQ) for L6565N 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 L6565N reliable?

The price and inventory of L6565N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6565N is usually 5 days.

3.What payment methods are accepted for L6565N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6565N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6565N?

L6565N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6565N 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 L6565N?

For technical support, including L6565N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6565N requirements.

6.How does Aetrix verify that L6565N is sourced from the original manufacturer or authorized distributors?

All L6565N 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 L6565N meets industry standards.

7.What is the process for return or replacement of L6565N?

All L6565N units undergo pre-shipment inspection (PSI). If there is an issue with L6565N, 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 L6565N part is unused and in its original packaging.

Return procedure for L6565N:

1.Submit a request within 90 days.

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

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