Cal Micro Drives White LEDs for Backlight or Flash

California Micro Devices offers the CM4072, a single-chip LED driver designed to power white LEDs to backlight TFT LCD display in wireless handsets, PDAs and LCD modules. The CM4072, part of CMD's PhotonIC™ family, comprises a low noise charge pump and linear regulator housed in a compact 3mm x 3mm 10-lead TDFN package.

The CM4072's small package size makes it optimal for mobile applications where space is critical. The CM4072 satisfies the need for superior performance, a compact footprint and a pricepoint demanded by the cost-driven wireless device marketplace.

The CM4072 integrates a charge pump and linear regulator into one package. The charge pump boosts the input voltage that is then fed to the linear regulator to produce 5V with an output current of 200mA. The ENABLE input can be used to control the LED brightness by modulating it with a PWM (pulse width modulated) signal from the baseband processor.

The charge pump operating frequency of 250kHz is well below the clock, cellular and PCS frequencies in wireless handsets minimizing the chance for any interference from the CM4072. The CM4072 is designed applications such as: White backlight LEDs for main display in wireless handsets and LCD modules and Power flash LEDs for camera phones.

The CM4072 with an output voltage of 5V is able to support LEDs that have forward voltages that range from 2.2V to 4.0V. Typical wireless handsets use about 3 to 4 white LEDs to backlight the main TFT LCD displays where each LED has a maximum of 25mA applied to it. Since the CM4072 can deliver up to 200mA of current, it can easily support 5 WLEDs at 25mA each to backlight higher resolution and larger size QVGA TFT LCD displays.

It can also be used in camera phones where a high brightness camera flash LED is used. The CM4072 can either drive three white LEDs with a maximum current of 65mA each or a single high brightness camera flash LED at 200mA. With the popularity of camera phones, two CM4072 LED drivers can be used in these designs where one is in or near the LCD module while the other is placed near the camera module.

The CM4072 is in production and priced at $0.69 each in 1,000 units lots.