ADI latest LED drive to improve the quality of camera phone camera image

Cellular mobile phone with integrated camera function becomes more and more common, the image quality has been greatly improved. However, the integration of new functions, such as video streaming, MP3, instant messaging and mobile e-mail threats to the development trend of improving the quality of the image, because the camera mobile phone design engineers need to control various functions by the battery power consumption limits. Analog Device Inc Adi (Analog Devices, Inc.), after the launch of the white LED camera flash function for mobile phone (LED) driver, it uses the new portable power management technique to maintain the image quality, even when the battery is in a variety of mobile phone functions while running under the condition of heavy load. When the camera mobile phone to receive RF (radio frequency) signal (whether it is the speech signal or data communication with the base station) and start the photoflash, power management technology can reduce the output current of the battery current is too large, so as to avoid the situation usually occurs in dark and grainy images. In the normal condition, a new ADI ADP1653 with high efficiency, high brightness, double white LED driver can make the flash brightness than single or low efficiency white LED driver, which can improve the image quality in low light intensity.

"When the mobile phone camera resolution to two million pixels or even higher light intensity high quality photo shoot need to be greatly increased," ADI portable power management product marketing director Arcadio Leon said. For the mobile phone, power efficiency and timing control play an important role in the process of reducing the battery current. For example, the existing charge pump solution at low battery voltage conditions its power efficiency is reduced to 40%, which means that less than half of the input power is converted to output power, and therefore more power consumption. The maximum power efficiency of ADP1653 is 92%, and in the full range of the lithium battery is usually greater than 80%."

In addition, boost DC/DC converter ADP1653 is different from the standard, it has a logic input pin, the pin in the mobile phone to start sending or receiving the RF signal power amplifier will be white LED current at 50 microseconds (s) is reduced to the lowest value in the work. The current timing control method further extends the battery life without compromising the image quality of the photo.

Save raw materials

Using ADP1653 and four small external components (a diode, a micro inductor and two capacitors) can develop a flash drive efficient solution. The external component cost required for this material list (BOM) is reduced by 50% compared with the existing high efficiency solution. The ADP1653 drives two tandem and current up to 500 mA high brightness white LED as well as a separate LED indicator. ADP1653 uses a I2C interface to support 2 or bit logic bus interface mode, which allows the design engineer can use external resistor or hardware to write data to the register settings on LED software. Safety features included in the ADP1653 (including soft start to reduce the inrush current), flash suspension (to prevent LED damage caused by overheating) and power N n-channel field effect transistor (NFET) functional limitations and current (the two overheating protection function can prevent the ADP1653 overheating).

Supply, packaging and quotation

ADP1653 can now provide product samples, and in February 2007 will be a large number of products. ADP1653 using 3mm * 3mm lead frame chip scale package (LFCSP), 1000 quantity quotation for 1.45 dollars / piece. The device in the industrial temperature range (40 ~ 85 C) reached the requirements of technical indicators.