The introduction of the United States to improve the reliability of the circuit design of the LED driver IC

United States MAX16826 integrated products (MAXIM Integrated Products) listed for the vehicle equipment LCD backlight and other areas, can improve the freedom of the circuit design of the LED driver IC". There are 4 channels to drive high brightness LED. Imagine each channel can be connected in series (such as 6 or 8) high brightness LED, each channel load current of 80 ~ 100MA (maximum 150MA). Can also set the output voltage of each channel. Therefore, to include all channels driving structure by using white LED; structure using 1 channels driving white LED, other 3 channels drive RGB; structure and the use of 3 channel, 1 channel driver RGB driver Amber LED. If you use all channels to drive the white LED, each channel can drive 8 LED, then a total of 32 can be lit up to a maximum current of 150mA white LED. Liquid crystal display device for vehicle navigation, instrument panel and liquid crystal display device for rear seat entertainment system.

In order to make each channel can load 80 ~ 100mA or more than the current of 80 ~ 100mA, the external channel can be adjusted FET. Each of the original channels can be driven by a maximum load current of LED in IC, FET integrated within the chip 50mA. If the structure of the built-in FET is intact, when the large current of the 100mA is passed, the heat output of the chip can be very large, which eventually leads to the overheating of the driving IC. For efficient heat dissipation, it is necessary to improve the installation of the IC backplane, so the design of the printing plate will reduce the degree of freedom. So the use of external FET method to facilitate FET cooling.

In addition, in MAX16826, the voltage of the drain and source of the FET is adjusted by the channel current. By monitoring the drain pole, which is the voltage between the LED and FET in each channel, the error of the LED forward voltage between the channels can be mastered. The drain voltage can be read by MAX16826 by CPU. In order to reduce the inter channel brightness error caused by the forward voltage error, the voltage can be used for each channel. The voltage read from the source is compared with the internal reference voltage in the drive IC to monitor the current flowing through the desired current. The internal reference voltage can be rewritten by I2C, CPU, etc.. The change function of the internal reference voltage can also be used to regulate the current in the flow channel.

MAX16826 input voltage range of +4.75 ~ 24V. Operating temperature range of -40 ~ +125 C. Package using 32 terminal TQFN. 1000 bulk purchase price of $2.05.

Source: Nikkei BP