Xenon lamp alternative high current WLED flash driver

The company has announced the addition of two new members to its increasingly high current white light emitting diode (WLED) flash drive. The product code for the dual channel AAT1271 and AAT1272 boost converter, with current up to 750 mA each support two WLED or with current up to 1.5A and the support of a WLED, and they are using the 3x3-mm compact TDFN package. They are the first such device on the WLED product line, which is equipped with a dedicated AS2Cwire interface and the industry standard I2C interface. The extra processing power of the two buses provides great flexibility for the designer to adjust the drive current to change the brightness of the WLED. At the same time, this boost converter with high drive current and small 3x3-mm accounted for the board area, providing a new attractive alternative to heavy xenon solutions.

Today, many digital cameras and cell phone camera to compensate for the deviation of the ambient light to maximize the quality of the picture. "Research Nobel lighting products product line director Phil Dewsbury explained:" the extra control using AS2Cwire and I2C bus, AAT1271 and AAT1272 allow designers to freely change the brightness and the brightness of the flash movie mode at multiple levels, and improve the image quality. "

Improved current control capability

AAT1271 and AA

T1272 both are high efficiency, high current boost converter, designed specifically for the LED camera flash applications. These two new devices are designed for a single lithium battery powered by the mobile system, which can be run in the 2.7V to 5.5V input voltage range. Two converters use up to 2 MHz switching frequency, by allowing the use of smaller external inductors and capacitors to help reduce the system accounting for the area of the board. They use 1 H inductor can get up to 85% efficiency.

The AAT1271 and AAT1272 have dual channels that are capable of driving up to two high current WLED with currents up to 750mA. In addition, these two channels can also be combined to drive a 1.5A with a current up to WLED. AAT1271 features a proprietary single line AS2C interface, while the AAT1272 provides the industry standard two-wire I2C interface.

These two converters provide a separate flash start and movie mode input mode to control the operation of flash and movie mode. The designers have adopted a single external resistor to set the full scale flash LED current and provide a preset value of 7.3:1 current ratio from flash to movie mode. Designers use the AS2Cwire or I2C interface to adjust the current of the movie mode to any other 15 levels in the preset range. In addition, AAT1271 added a can be used in GSM mobile application of flash suppression to reduce the input of the power amplifier (PA) flash current transmission, so as to avoid the high battery current conditions to restart the system by the battery depletion caused by.

In view of their high drive current capability, the two converters also have the ability to limit the input current and a real load disconnect switch, the supply current can be reduced to 1 A.

The two new converter also includes a user programmable flash safety timer. This function can be used in the case of software failure to protect the flash LED free from thermal damage, through the termination of the flash signal without considering the flash signal conditions. Using AS2C or I2C bus, the security timer can be programmed at 16 different levels.

Source: EDN China