Low-dropout LED drivers for any-colour chips

June 22, 2015 // By Graham Prophet
Ams has posted details of the AS1111x family of high efficiency LED drivers designed to match current source bias for any colour LED, including white and blue.

The devices can drive up to four high-current LEDs; the LED current can be adjusted using an external resistor (RSET) and dimmed with an external PWM signal via the EN pin. It only requires 150 mV headroom voltage to operate and when the devices are disabled, the supply current drops down to less than 1 µA.

Features include; up to four channels of 40mA drive (for high brightness LEDs); 150 mV headroom to operate (efficiency & battery lifetime); analogue or PWM brightness control with high resolution; no switching noise for EMI-sensitive environments; and fewer external components required.

LED current per output is 40 – 80 mA, with 3% LED-to-LED matching, from a supply voltage of 0.15 to 3.6V. Packaging is WL-CSP-6, 0.4 mm pitch (AS1111A & AS1111B), MLPD-8, 0.5 mm pitch (AS1111C), and pricing is from $0.19 (1000).

ams; ams.com/eng/Products/Lighting-Management/LED-Driver-ICs/AS1111