Tiny Boost Converters Drive Three, Four, Or Five LEDs

A family of synchronous boost converters in 1.5- by 1.5-mm packages can power up to five series of white LED backlights in smart phones, PDAs, digital still cameras, and other handheld electronics. Texas Instruments' TPS6106x family of specialized dc-dc converters supports input voltages from 2.7 to 6 V and integrates a 400-mA power MOSFET and synchronous rectifier, eliminating the need for an external series Schottky diode. Their 1-MHz fixed switching frequency enables the converters to work with smaller, low-value external components, such as a 10-µH inductor and a 220-nF output capacitor. Brightness can be controlled stepwise via a host microcontroller's general-purpose input/output pin by applying a pulse-width modulation (PWM) signal to the chip enable pin or by introducing an analog signal to the feedback input. In shutdown, the parts consume less than 3 µA. The three-LED TPS61060, four-LED TPS61061, and five-LED TPS61062 cost $1.35, $1.40, and $1.45 each in 1000-unit quantities.

Texas Instruments
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