Smartlight driver integrates control of three separate banks of smart indicator LEDs

Smartlight driver integrates control of three separate banks of smart indicator LEDs

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By eeNews Europe

The device is useful for many consumer electronics devices such as 3G and LTE modems, USB memory sticks, game controllers and headsets in which indicator lighting can enhance the user interface, and in which high-value light effects and low power consumption are required.

The AS3661 allows easy command-based programming of all light patterns. Three independent program execution engines form three independently programmable LED banks. This means that LED drivers can be grouped based on their function so that, for example, the first bank of drivers could be assigned to keypad illumination, the second bank to ‘funlights’ (patterns of light outputs produced by multiple LEDs), and the third group to notification LED(s).

Each bank can contain from one to nine LED driver outputs; the AS3661 offers nine LED channels in total with up to 25 mA per channel. A dedicated 12-bit PWM for each of the nine channels delivers absolutely smooth color transitions and enables the production of linear, logarithmic and ratiometric fading effects.

Instructions for the program execution engines are stored in the program memory. The total capacity of the program memory is 96 instructions and the user can allocate a memory of 1.5 kbit as required by the engines. The AS3661 smart LED driver has an I2C-compatible control interface with four pin-selectable addresses. The device also has a flexible General Purpose Output (GPO) which can be used as a digital control pin for other devices. The INT pin can be used to notify the central processor when a lighting sequence has ended. The device also provides a trigger input interface which allows for synchronization between multiple devices.

To optimize battery lifetime the design of the AS3661 includes various power-saving features. Each channel operates on a dropout voltage of less than 50 mV at 10 mA powered by a high-efficiency 150 mA charge pump with automatic switching between 1:1 and 1:1.5 mode. Furthermore, a power save mode is automatically entered when LED outputs are not active, resulting in a low idle mode current of 10 μA (typical).

The AS3661 complements the existing ams family of smartlight drivers consisting of:

  1. the AS3665, a larger version of the AS3661, which also addresses nine LEDs but which also has an audio synchronization mode in which the LED changes brightness and color in response to audio inputs
  2. the AS3668, a  simple and smart four-channel RGBW driver.

Availability and Pricing

The AS3661 is available in a small 2.285 mm x 2.285 mm 25-bump WL-CSP requiring few external components. The device is in volume production, priced at $1.15 for 1,000 pieces.

Visit ams at

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