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STMicroelectronics L6566BH
- Part No.:
- L6566BH
- Manufacturer:
- STMicroelectronics
- Category:
- AC DC Converters, Offline Switches
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
L6566BH.pdf
- Description:
- IC OFFLINE SWITCH FLYBACK 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:209
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Product details
Overview
L6566BH from STMicroelectronics is a multimode current-mode primary controller IC for offline flyback SMPS, supporting both fixed-frequency (FF) and quasi-resonant (QR) operation with 840 V high-voltage startup, adaptive UVLO, and programmable frequency modulation. It delivers -600/+800 mA totem-pole gate drive, features transformer saturation detection, and enables constant-power regulation via line voltage feedforward - deployed in industrial 3-phase rectified input power supplies.
For engineers reviewing the L6566BH datasheet, L6566BH pinout, L6566BH application, or L6566BH equivalent, key selection considerations include QR/FF mode configurability, 70% min. duty cycle limit in FF mode, valley-skipping at light load, latched/auto-restart OVP/OCP options, and brownout protection with 0.45 V threshold on AC_OK pin.
Technical Context
The L6566BH implements dual-mode control logic: in QR mode, ZCD pin (11) senses transformer demagnetization to enable zero-voltage switching, while MODE/SC pin (12) selects QR by connection to VREF (10); in FF mode, OSC pin (13) sets switching frequency directly via external resistor, and slope compensation is applied via MODE/SC–CS (7) resistor network. The oscillator supports spread-spectrum FMOD (pin 6) for EMI reduction.
Protection architecture includes two-level OCP: pulse-by-pulse current limiting at CS (7) with 1.5 V latch threshold for transformer saturation or secondary diode short-circuit, and hiccup-mode overload shutdown triggered by SS (14) capacitor discharge timing. Brownout (AC_OK, pin 16) and OVP (ZCD, pin 11) are independently configurable for latch or auto-restart behavior.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Startup Voltage Rating | 840 V on HVS pin (1) - enables direct connection to rectified 3-phase mains without external HV resistor network. |
| Gate Drive Strength | -600/+800 mA totem-pole output on GD pin (4) - sufficient to drive high-Ciss MOSFETs/IGBTs without external buffer in <500 W designs. |
| Quiescent Current | <3 mA - ensures low no-load consumption, critical for meeting EU CoC Tier 2 and ENERGY STAR standby requirements. |
| Line Feedforward Range | 0–3 V on VFF pin (15) - scales current-limit threshold inversely with input voltage to maintain constant output power across 380–480 VAC 3-phase inputs. |
| Brownout Threshold | 0.45 V on AC_OK pin (16) - non-latched shutdown below this level, with 15 µA hysteresis current to prevent chatter during voltage sag. |
| Oscillator Frequency Range | 20–500 kHz (FF mode), max 500 kHz (QR mode) - set by resistor from OSC (13) to GND; modulated via FMOD (6) for EMI spread spectrum. |
| Duty Cycle Limit | 70% minimum in FF mode - enforced by internal logic to ensure safe MOSFET conduction margin and avoid sub-harmonic oscillation. |
Pinout & Package
Package: SO16N (16-pin small outline, 1.27 mm pitch, body width 3.9 mm, JEDEC MS-012AC compliant).
| 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 reference for all analog blocks and driver stage; requires dedicated low-impedance PCB trace separate from power ground loops. |
| 4 GD | Gate driver output | Totem-pole stage with active pull-down during UVLO - prevents MOSFET floating during startup/fault conditions. |
| 5 VCC | Internal supply rail | Powered by HVS startup circuit; UVLO thresholds adapt dynamically (e.g., 13.5 V turn-on, ~5 V shutdown, reduced at light load). |
| 7 CS | PWM current sense input | 150 ns leading-edge blanking; dual-threshold comparator (0.45 V for OCP, 1.5 V for saturation latch) with digital noise filtering. |
| 11 ZCD | Zero-current detection / OVP input | Negative edge triggers QR turn-on; >5 V triggers OVP shutdown - strobed and digitally filtered for immunity to ringing. |
| 12 MODE/SC | Mode selection / slope compensation | Connected to VREF → QR mode; tied to CS via resistor → FF-mode slope compensation to prevent sub-harmonic instability. |
| 14 SS | Soft-start / fault timing | Capacitor-based ramp controls duty-cycle rise at startup; same capacitor delays shutdown after OCP detection (latch/auto-restart selectable). |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive UVLO | UVLO turn-on threshold drops at light load to counteract self-supply voltage sag caused by transformer leakage, preventing false shutdown. |
| Valley skipping in QR mode | At medium/light load, skips switching cycles to maintain operation near transformer resonant valley - preserves ZVS benefit without excessive frequency rise. |
| Programmable burst-mode entry | Triggered by COMP pin (9) voltage falling below internal threshold - enables controlled low-power operation with <3 mA quiescent current. |
| Transformer saturation detection | CS pin (7) second-level comparator at 1.5 V latches off IC on sustained overcurrent - distinguishes hard short from transient overload. |
| External OTP integration | DIS pin (8) accepts >4.5 V to latch-disable IC - allows simple NTC-based thermal protection with fast restart via AC_OK pin override. |
Applications
| Industrial 3-Phase SMPS | Single-Stage PFC Flyback |
|---|---|
|
Use Scenario: 380–480 VAC rectified input powering PLC I/O modules with strict EN61000-3-2 Class A harmonic limits. IC Role / Device Role / Timing Role: Primary-side current-mode controller managing QR flyback topology with line feedforward to maintain constant output power across input range. Use Value: Eliminates need for secondary-side feedback optocoupler and TL431; achieves >88% efficiency at full load and <300 mW no-load consumption. |
Use Scenario: Single-switch, single-stage AC-DC converter for LED drivers requiring compliance with JEITA-MITI harmonic standards. IC Role / Device Role / Timing Role: Dual-function controller implementing input-current shaping and isolated DC output regulation in one IC - uses VFF and ZCD pins synergistically. Use Value: Reduces BOM count by 30% vs. two-chip PFC+flyback solution; maintains THD <10% at 100% load without additional filter stages. |
| High-Voltage Industrial PSU | Energy-Efficient Server Auxiliary Supply |
|
Use Scenario: 1 kW industrial power supply with 3-phase input, requiring robust brownout recovery and transformer saturation protection. IC Role / Device Role / Timing Role: Primary controller enforcing 70% duty cycle limit in FF mode, using AC_OK (16) for fast brownout response and CS (7) for dual-threshold OCP. Use Value: Survives 200 ms 30% voltage sags without reboot; detects winding short within 3 switching cycles via 1.5 V saturation latch. |
Use Scenario: 24 W auxiliary supply for server management controllers (BMC), mandated to meet 80 PLUS Titanium standby power limits. IC Role / Device Role / Timing Role: Burst-mode controller with adaptive UVLO and programmable soft-start - minimizes no-load losses while ensuring reliable cold-start at -40°C. Use Value: Achieves 180 mW no-load input power; soft-start capacitor (SS pin) provides 120 ms ramp time to prevent inrush-induced transformer saturation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multimode flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28064A | Fixed-frequency only; no QR capability; 600 V startup; no adaptive UVLO; integrated 5 V LDO instead of VREF. | Lacks valley skipping and ZVS support - unsuitable for high-efficiency QR designs above 250 W; better for cost-sensitive FF-only industrial supplies. | Select when QR operation is unnecessary and BOM simplification via integrated LDO outweighs efficiency loss. |
| ICE2QS03G | QR-only operation; 650 V startup; no line feedforward; no programmable burst-mode; lower gate drive (±500 mA). | Cannot support constant-power regulation across wide 3-phase input range; limited to single-phase or narrow-input QR flybacks ≤150 W. | Choose only for low-cost, single-phase QR adapters where feedforward and high-voltage startup are not required. |
Compared with UCC28064A and ICE2QS03G, the L6566BH uniquely combines 840 V startup, adaptive UVLO, and dual-mode (FF/QS) operation - enabling robust, high-efficiency designs across 3-phase industrial inputs while maintaining design flexibility for both constant-power and burst-mode optimization.
Availability
L6566BH is available at Aetrix Electronics and suitable for industrial SMPS, 3-phase rectified input power supplies, and single-stage PFC flyback converters requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for L6566BH 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 silicon solutions for automotive, industrial, power, and embedded applications.
The L6566BH belongs to ST's high-voltage analog power controller product line, engineered specifically for robust, high-efficiency offline flyback converters operating from rectified 3-phase mains - emphasizing reliability under wide input voltage swings and harsh industrial environments.
FAQ
What is the purpose of the MODE/SC pin (12) in FF versus QR operation?
In QR mode, MODE/SC must be connected to VREF (pin 10) to enable demagnetization sensing via ZCD (pin 11); in FF mode, it's left unconnected and used to inject slope compensation current into CS (pin 7) via an external resistor - preventing sub-harmonic oscillation when duty cycle exceeds 50%. The pin also outputs a synchronized ramp during gate drive high-time in FF mode.
How does the L6566BH implement adaptive UVLO, and why is it needed?
Adaptive UVLO dynamically lowers the VCC shutdown threshold at light load to compensate for self-supply voltage sag caused by transformer leakage inductance and parasitic capacitance. This prevents premature shutdown during low-power operation - confirmed by internal monitoring of VCC decay rate and adjustment of the 5 V UVLO floor downward by up to 1.2 V depending on load condition.
Can the L6566BH support both latched and auto-restart protection modes simultaneously?
No - latched and auto-restart behaviors are selected per-protection function via external resistor networks. OVP (ZCD pin) and OCP (SS pin) each have dedicated configuration options: for example, tying ZCD to VREF enables latched OVP, while connecting it through a resistor to GND enables auto-restart. These are independent settings, not global modes.
What is the functional difference between the two OCP thresholds on the CS pin (7)?
The CS pin has two comparators: the primary 0.45 V threshold triggers pulse-by-pulse current limiting and hiccup-mode shutdown after timeout; the secondary 1.5 V threshold detects transformer saturation or secondary diode short-circuit and immediately latches off the IC until VCC falls below UVLO. This dual-level scheme distinguishes transient overloads from catastrophic faults.
L6566BH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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
L6566BH FAQ
1.How can I place an order for L6566BH through Aetrix?
Please submit a Request for Quotation (RFQ) for L6566BH 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 L6566BH reliable?
The price and inventory of L6566BH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6566BH is usually 5 days.
3.What payment methods are accepted for L6566BH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6566BH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L6566BH?
L6566BH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L6566BH 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 L6566BH?
For technical support, including L6566BH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6566BH requirements.
6.How does Aetrix verify that L6566BH is sourced from the original manufacturer or authorized distributors?
All L6566BH 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 L6566BH meets industry standards.
7.What is the process for return or replacement of L6566BH?
All L6566BH units undergo pre-shipment inspection (PSI). If there is an issue with L6566BH, 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 L6566BH part is unused and in its original packaging.
Return procedure for L6566BH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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