The first driver on this new platform is the iW3626, a single-stage driver with up to 10W output for 60W equivalent dimmable incandescent bulbs. The iW3626 enables solid-state lighting designers to reduce the bill of materials (BOM) cost by up to 20%(1) compared to competitive solutions and is believed to be the first SSL LED driver to offer integrated, configurable power factor correction (PFC) to control the balance between PFC and output current ripple. Furthermore, integrated, configurable over-temperature protection (OTP) with derating enables a bulb with a predictable and reliable lifespan. This combination of features offers LED bulb manufacturers a new way to design products for applications seeking to replace non-dimmable incandescent bulbs at a lower cost and with higher performance than SSL products currently available.
The iW3626 was developed in close cooperation with key iWatt customers, including Eastfield International Industries, Ltd., which has implemented the iW3626 in its latest generation of SSL dimmable bulbs.
Global regulations govern minimum performance requirements, such as PFC and input harmonics, and these regulations vary by country and application. In single-stage LED drivers, there is a correlation between improved PF and increased output ripple. Using a novel, patent-pending, configurable PFC technique, the iW3626 allows designers to choose a PF between >0.7 and >0.9, facilitating compliance with various global regulations while effectively managing the balance between PF and output ripple. This balance ensures that the required PF can be achieved with low output ripple, minimizing both heat generation and flicker, without increasing cost or size.
The iW3626's temperature protection function, with automatic brightness reduction based on temperature, is integrated into the same IC and measures the temperature inside the sealed SSL bulb. When the thermal conditions reach the point programmed by the design, the iW3626 LED driver automatically reduces the output current powering the LEDs, thus reducing the heat dissipated by the LEDs and, consequently, the system temperature. This function reduces the risk of thermal damage from overheating and ensures that the temperature of the electrolytic capacitors in the system does not exceed its allowable level, thereby ensuring a predictable lifespan. Additional features include LED open/short circuit detection, input overvoltage protection, output overcurrent protection, and protection for the resistor that acts as the primary current sense on the primary side.
The iW3626 achieves up to 20% savings in the total cost of ownership (BOM) with its high level of integrated features. It allows the replacement of FETs with low-cost bipolar junction transistors (BJTs), eliminating the need for high-voltage electrolytic capacitors, and includes integrated configurable temperature protection. Furthermore, iWatt's patented PrimAccurate™ primary-side control technology eliminates the need for a secondary-side regulator and optical feedback.
The iW3626 is packaged in a standard, low-cost, 6-pin SOT23 package, which can be implemented on a single-layer board for additional savings and a smaller footprint.
iW3626 Features
• Output Power: 10W (equivalent to a 60W incandescent bulb)
• Configurable power factor from >0.7 to >0.9
• PrimAccurate primary-side control reduces solution size, lowers BOM cost, and increases reliability
• Up to 20% BOM savings(1)
• High efficiency >85% at 220VAC
• Precise LED current control, maximum tolerance of ±5%
• LED temperature protection with auto-down function
• Meets global standards, including EU IEC61000-3-2(2)
• Small SOT-23 package
(1) The bill of materials (BOM) cost comparison is based on an analysis by iWatt using typical published application circuits.
(2) European Power Supply Manufacturers Association standard - IEC 61000-3-2
