Super barrier rectifiers for efficient retrofit LED lighting

June 29, 2016 // By Graham Prophet
The SBRT3M40P1 Trench Super Barrier Rectifier (SBR) (Diodes Inc) is optimized to deliver a low forward-voltage drop in a small form factor while maintaining low reverse-current leakage. This capability addresses requirements for input bridge rectifiers in solid-state lighting (SSL) applications focused on 12V AC LED retrofit lamps, which provide a more efficient and longer life alternative to popular MR16 halogen bulbs.

Operating at +125°C, this 40V rated trench SBR, has a low reverse-current leakage of only 1.2 mA at 12V blocking, which provides immunity to thermal runaway under the high ambient temperature environment of an MR16 retrofit. It maximizes the 1A bridge rectifier efficiency and power density with only a 0.29V forward-voltage drop in a compact PowerDI123 footprint of 6.75 mm ².


To minimize forward loss, the SBRT3U40P1 is an alternative device that provides a lower forward-voltage drop of 0.25V at the expense of an increase in the reverse-current leakage to 4 mA. Options for different forward loss and reverse leakage enable the rectification circuit to be optimized depending on the waveform’s duty cycle requirements and operating temperature.


A 40V blocking capability normally provides sufficient headroom for a 12V AC input supply. However, if the line regulation is poor then the SBRT3M60P1 and SBRT3U60P1, with their 60V blocking capability, give extra headroom at the expense of their slightly higher forward-voltage drop of 0.34V and 0.28V, respectively.


While a conventional SMA package option is available, the PowerDI123 package offers a smaller footprint (6.75 mm ² compared to 16 mm ²) and lower height profile (<1 mm compared to 2 mm) for space-critical applications such as the target MR16 retrofit bulb market.


SBRT3M/U SBRs are priced at $0.12 (3000).