WLED flash drivers deliver two interfaces for greater flexibility

Santa Clara, Calif. — Advanced Analogic Technologies Inc. (AnalogicTech) has expanded its high-current white LED (WLED) flash driver family with the introduction of two dual-channel boost converters. Supporting either two WLEDs at up to 750 mA each or one WLED at up to 1.5 A, the AAT1271 and AAT1272 are the first devices of their type in AnalogicTech's WLED driver product line to feature the company's proprietary single-wire AS2Cwire interface and industry-standard I2C interface, respectively. The additional addressing capability of these two buses delivers the flexibility to modify drive current, and therefore WLED brightness, said the company.

In addition, the boost converters' high drive current coupled with the small 3 x 3-mm TDFN package makes them suitable as an alternative to larger xenon lamp solutions.

Both the AAT1271 and AAT1272 are high-efficiency, high-current boost converters designed for LED photo flash applications. Operating off a 2.7-V to 5.5-V input voltage range, the two new devices are targeted at single-cell Lithium-ion battery-powered mobile systems. Both converters use a high 2-MHz switching frequency which helps reduce system footprint by allowing the use of smaller external inductors and capacitors. The two new converters can achieve up to 85% efficiency with 1 μH inductors.

Both converters supply separate flash enable and movie-mode enable inputs to control flash and movie-mode operation. Designers use a single, external resistor to set full-scale flash LED current. A default 7.3:1 flash-to-movie-mode current ratio is provided. Designers can adjust the movie-mode current level from the default setting to any of 15 other levels using either the AS2Cwire or I2C interface. The AAT1271 also adds a flash inhibit input that can be used in GSM mobile applications to reduce the flash current during PA transmission to avoid a system reset due to excessive battery droop in high battery current conditions.

Given their high drive current capability, both converters also feature input current limit capability and a true load disconnect switch that reduces supply current in shutdown to < 1μA. The new converters also include a user-programmable flash safety timer. This function can be used to protect the flash LEDs from thermal damage in the event of a software failure by terminating the flash pulse regardless of the FL enable signal condition. Using the AS2C or I2C bus, the safety timer can be programmed across 16 different levels. Both devices are qualified across the -40°C to +85°C temperature range.

Pricing: The AAT1271 and the AAT1272 sell for $1.49 in quantities of 1,000.

Product information: AAT1271

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