Date: 21/12/2009

LED driver ICs from IXYS for photo flash apps

IXYS has introduced the LDS8640/41 and LDS8680/81, a new two channels, charge-pump based, high efficiency LED driver ICs with low dropout voltage, and suitable for HB LED photoflash for digital cameras, video cameras, cell phones, smart phones, flashlights and security light flashers applications.

These LED driver ICs provide output power from a single-cell lithium ion battery or supply voltage in the range of 2.7V to 5.5 V. The LDS8680 has two channels, one channel can drive one HB LED up to 800mA, and the other channel can drive up to 400mA. For flash applications using two HB LEDs, LDS8680 can simultaneously drive both HB LEDs at 400 mA each. The LDS8680 uses a SmartOne Wire interface to adjust LED currents ranging from 50 to 800 mA in 31 steps for one channel and from 50 to 400 mA in 15 steps for the other channel. It also allows PWM dimming to adjust LED brightness. Every channel may be turned on/off or programmed separately. The LDS8681 drives LEDs with a preset maximum LED current of 400 mA per channel and uses PWM dimming control for LED brightness adjustment.

The LDS8640/41 family is similar in function to the LDS8680/81, but with low current ratings. The LDS8640 can drive one channel up to 400mA, and the other channel up to 200mA, or drive two HB LEDs simultaneously at 200mA each. The LDS8641 is preset to maximum LED current at 200mA per channel, with PWM dimming control.

Both LDS8680 and LDS8681 may be used in "cinema" mode with 60 or 120 flashes per second if pulse length does not exceed the LED's thermal dissipation limit. Each device can operate in 1-x and 2-x charge-pump modes and the inclusion of a low dropout PowerLite Current Regulator (PCR) operating down to 150 mV increases the device efficiency up to 90%.

The device exhibits a robust protection system (over-voltage, over-temperature, under-voltage and short-circuit), while the shutdown current is below 1 microA. To protect HB LEDs from thermal damage, a timeout protection is permanently "on" in the DS8641/81, while it can be disabled by SmartOne Wire interface in the LDS8640/80.

Package: 2 x 3 x 0.8 mm 8-pin TDFN package
Availability: Now

For more details visit www.ixys.com