Power Integrations has published a new reference design for a 25-watt LED T8 tube ballast power supply. With an efficiency better than 91%, the DER-287 design also meets commercial requirements for power factor (PF greater than 0.9) and harmonic distortion (EN61000-3-2 Class C).

Figure 1. Typical Application Schematic

LinkSwitch-PH dramatically simplifies implementation of LED drivers requiring Power Factors greater than 0.9, TRIAC dimming, and high efficiency. This highly integrated controller introduces a new control technique that provides very high power factor and accurate output current control, and eliminates passive circuitry required for power factor correction, optocoupler and secondary current control circuitry.

Each device incorporates a 725V power MOSFET, a continuous-mode PWM controller, a high voltage switched current source for self biasing, frequency jittering, cycle-by-cycle current limit and hysteretic thermal shutdown circuitry into a monolithic IC.

Product Highlights

Dramatically Simplifies Off-line LED Drivers

• Single-stage power factor correction and accurate constant current (CC) output
• Flicker-free, phase-controlled TRIAC dimming
• Eliminates optocoupler and all secondary current control circuitry
• Eliminates all control loop compensation circuitry
• Simple primary-side PWM dimming interface
• Universal input voltage range
• Enables designs that are electrolytic-free
  

Accurate and Consistent Performance

• Fast start-up time
• Compensates for transformer inductance tolerances
• Compensates for line input voltage variations
• Frequency jittering greatly reduces EMI filter size and costs

Advanced Protection and Safety Features

• Auto-restart for short circuit protection
• Open circuit fault detection mode
• Automatic thermal shutdown or restart with hysteresis
• Meets high voltage creepage requirement between DRAIN and all other signal pins both on PCB and at package

EcoSmart^® - Energy-Efficiency Technology

• Low standby power remote ON/OFF feature (< 50 mW at 230 VAC)
• No current sense resistors - maximizes efficiency
• High efficiency operation, >85% achievable
  

Green Package

• Halogen free and RoHS compliant package