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The AL1666 is a high performance single stage Flyback and Buckboost controller, targeting dimmable LED lighting application. It is a primary side regulation (PSR) controller which can provide accurate Constant Current (CC) regulation without opto-coupler and secondary control circuitry. It is operating at BCM mode which results in good EMI and efficiency, and keeps high PF and low THD under universal input voltage.

The AL1666 can support analog/PWM dimming modes. When a 0 to 2.4V DC signal is applied on ADIM pin, the device will operate in analog dimming mode; when a digital signal is applied on PWMD pin and the ADIM pin is connected with hundreds of nF capacitors, the device will work at PWM-to-DC dimming mode. The dimming range is 1% to 100%.

The AL1666 has rich protection features. It integrates multiple protections including Under Voltage Lock Out (UVLO), Output Over Voltage Protection (OVP), Output Short Circuit Protection (OSP), Over Current Protection (OCP), Winding Short Circuit, Secondary Diode Short, Internal Thermal Fold-Back Protection (TFP) and Over Temperature Protection (OTP).

The AL1666 is available in SO-8 (Standard) package.


  • General LED Lighting Driver with Dimming Function
  • 0 to 10V Dimming Luminaires
  • General Purpose Constant Current Source
  • Smart LED Lighting


  • Primary Side Regulation without Opto-Coupler
  • Valley Switching for Low Switching Loss
  • Support Analog and PWM-to-DC Dimming
  • Analog/PWM-to-DC Dimming Range: 1% to 100%
  • Tight CS Reference Voltage 0.4V±1.5%
  • High PF>0.9 and Low THD<20%
  • High Efficiency
  • Internal Protections
    • Under Voltage Lock Out (UVLO)
    • Output Over Voltage Protection (OVP)
    • Output Short Protection (OSP)
    • Over Current Protection (OCP)
    • Winding Short Circuit Protection
    • Secondary Diode Short Protection
    • Internal Thermal Fold-back Protection (TFP)
    • Over Temperature Protection (OTP)
  • Tight LED Current Variation Range
    • LED Current Line Regulation: ±2% (90VAC to 305VAC)
    • LED Current Load Regulation: ±2% Full Load to Half Load
  • Package: SO-8 (Standard)
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)
  • For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP
    capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/

Product Specifications

Product Parameters

Minimum Input AC Voltage (VAC) 85
Maximum Input AC Voltage (VAC) 305
Maximum DC VDD (VDC) 18.5
LED Current (mA) External MOSFET
Frequency (kHz) 80K
Accuracy 1.5 %
Efficiency > 85 %
Dimming Analog, PWM to Analog
Supply Current 2 mA
Temperature Range -40 to +105 °C

Technical Documents

Evaluation Boards and User Guides

Recommended Soldering Techniques



Orderable Part Number Authorized Distributor Quantity Inventory Date Buy Online Region
AL1666S-13 Digi-Key Electronics 3625 9/24/2020 Buy Now United States
AL1666S-13 Mouser Electronics Inc. 7827 9/24/2020 Buy Now United States