Product category:
Power Supply ICs and Controllers
News Release from: Advanced Analogic Technologies | Subject: AAT1231
Edited by the Electronicstalk Editorial
Team on 26 July 2006
Single-wire, digital brightness control
The former de facto standard PWM technique to control series-connected LEDs has been surpassed by AnalogicTech's AAT1231.
The former de facto standard PWM technique to control series-connected LEDs has been surpassed by AnalogicTech's AAT1231 By utilising the device, designers can use a single wire to digitally control white LEDs, giving flicker-free light output, reduced MCU clock cycles, a saving of GPIO resources, and providing a complete solution for portable applications that uses fewer components
This article was originally published on Electronicstalk on 19 Sep 2008 at 8.00am (UK)
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PWM produces variations in current and therefore LED brightness.
Additionally, the control methods required for the old technique consume microcontroller processing resources, require GPIO interfaces, and demand a large number of additional components.
The AAT1231 overcomes all of these problems.
The AAT1231 is a high frequency, high efficiency inductive boost DC/DC convertor for controlling white LEDs in portable systems operating from single-cell lithium ion/polymer batteries.
Delivering 50mA up to 24V, the device is capable of driving up to six white LEDs in series or up to 12 white LEDs in a parallel/series configuration using AnalogicTech's digital Simple Serial Control (S2Cwire) single-wire interface.
LED output current on the AAT1231 is controlled using AnalogicTech's S2C wire interface in 16 linear steps.
By changing the feedback voltage with the SEL pin, designers can extend the output voltage another 16 levels.
This allows designers to Oset and forget' the output across a total of 26 steps (after overlap) from 7.5% to 100%.
Digital control improves display readability by providing constant flicker-free LED output.
The AAT1231's high, 2MHz switching frequency provides fast response to load transients and permits the use of small external components including a 2.2microH inductor.
The AAT1231 delivers an overall efficiency up to 82%.
The device also adds a true load disconnect feature which completely isolates the load from the power source.
By reducing leakage current to less than 1microA, this function extends battery life and system standby time.
AnalogicTech's AAT1231 also offers a wide variety of standard protection features, including integrated soft-start, current limit, over-temperature, and over-voltage protection.
Specified over the -40 to +85 degrees C temperature range, the AAT1231 is immediately available in a Pb-free, 12-pin TSOPJW package.
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