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IR control IC eyes electronic transformers

Posted: 27 May 2004 ?? ?Print Version ?Bookmark and Share

Keywords:international rectifier? ir? control ic? ir2161? adaptive deadtime control?

International Rectifier (IR) disclosed that it has developed the first intelligent control IC specifically designed for electronic transformers that drive low voltage halogen lamps.

Integrating all the necessary features into a single 8-pin DIP or SOIC, the IR2161 reduces parts count, simplifying circuits and increasing reliability. It can adapt to changing supply voltage, frequency conditions, and lamp conditions, enabling the introduction of highly-reliable halogen transformers while streamlining their design and manufacture.

Featuring the company's rugged high voltage IC technology, the 8-pin device incorporates a 600V half-bridge driver, advanced overload and short circuit protection circuitry with high temperature shutdown and adaptive control techniques. It also accommodates external dimming with a standard phase-cut, triac-based dimmer. According to IR, the IR2161 can reduce component count by 20 percent when compared to similar circuits using discrete components.

A key feature of the IR2161, the Adaptive Deadtime Control increases transformer reliability by continually maintaining soft switching. The IC has an active deadtime circuit that detects the point at which the DC bus voltage in the half bridge slews to 0V and sets the low-side driver (LO output) high. An internal sample and hold system allows approximately the same delay to be used to set the high-side driver (HO output) high after LO has gone low. Adaptive deadtime control reacts on a cycle-by-cycle basis of the oscillator and adjusts dead time as necessary to maintain soft switching regardless of external conditions.

The new IC is based on the company's high voltage junction-isolation (HVJI) IC technology. This proprietary technology allows high voltage circuits to be isolated from low voltage circuitry, so that both high- and low-side drive functions can be housed on a single, compact chip for controlling various switching converter topologies.

Key specifications for the IR2161 include output drive capability of 250/400mA, 15.6V zener diode clamp on Vcc, micropower startup of <300?A, and built-in 30kHz to 125kHz oscillator.

Pricing for the IR2161 begins at 73 cents each (IR2163S) in 100,000-piece quantities.

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