Maxim white light LED charge pump with integrated camera power supply

Maxim introduced the smallest white LED (WLED) driver MAX8645X/MAX8645Y, the device built-in two LDO, can be used as a camera power supply. The series charge pump integrates a white LED (backlight) driver, a camera flash driver, and a camera power supply in a single chip IC, reducing the required area by 40%. This series of devices is most suitable for folding, sliding type mobile phones and smart phones, such applications in the liquid crystal display (LCD) and camera modules are usually located in the upper half of the phone, the space is very compact.

MAX8645X/MAX8645Y integrated two programmable 200mA LDO for the camera module power supply. These LDO have a lower noise (40 VRMS, typical), to ensure that when the image is guaranteed to clean and stable power supply. This feature is very important for reducing the noise of the images in the current and next generation mobile phones. Nine different output voltages can be selected through the two control pins, which simplifies the procurement and inventory requirements.

After the use of charge pump regulator, without the use of inductance, so the thinnest design can be achieved. In addition, the device uses a proprietary adaptive 1x/1.5x/2x charge pump as well as a very low dropout current regulator that can achieve a high efficiency of 85% (over the entire Li battery life cycle of PLED/PBATT). The MAX8645X/MAX8645Y has a fixed switching frequency of 1MHz, which can be used to reduce the size of the overall scheme by using micro external components. This series of devices can be up to 30mA/LED current drive six WLED, with 5 dimming resolution and 0.2% (typical) current matching; the series of devices in 200mA/LED current can drive two flash LED, and has a 5 bit resolution. Dimming control can be achieved by a simple 2 bit logic interface, or if you want to improve the resolution, you can also connect the logic pin to form a serial pulse interface for dimming. Other features include soft start, reduced input surge current, and proprietary over temperature derating function that reduces the drive current to protect LED when operating at high temperatures.

MAX8645X/MAX8645Y uses a miniature, 4mm x 4mm x 0.8mmTDFN package, which works in the extended temperature range (-40 C to +85 DEG C). The evaluation board is available to speed up the design process.

Source: electronic system design