Because the LED's brightness is determined through the current, in order to maintain the same brightness, all the LED will need to keep the current flowing through the same, and most of the battery or other power source are similar to those of constant pressure, and the output voltage and with the reduce the use of time, direct the use of batteries in parallel LED light will not only result in brightness is not constant, but also caused by imbalance in the various LED currents so as to shorten the number of LED life. Thus require the use of constant current source to drive the LED, the LED driver IC is actually a general power converted into the constant current source, which is why the need for the causes of LED driver IC, China last year produced 30.7 billion LED, even if Of these, only one-tenth of a LED driver IC, taking into account the number of driver IC, a number of lit LED, so it needs at least hundreds of millions of driver IC, so this is a very big market.

        Power Analog Microelectronics has developed a series of LED driver IC, has now entered mass production PAM2701 is used to drive a mobile phone or PMP's lcd screen backlight LED, this is a chip charge pump requires only four additional ordinary low-cost ceramic capacitors can work on. It can drive up to 4 Forward Current 30mA of LED, and to ensure that each of the current was less than 3% of the LED lighting required by three control lines to select. It can work on the lithium battery voltage higher than the LED's forward voltage, but also can work on the lithium battery voltage lower than the LED's forward voltage, and can automatically switch its mode. Its maximum efficiency as high as 91%. The package is used in very small QFN size 3x3mm and 4x4mm in QFN.

         In order to ensure the flow of all the LED current as the other most convenient way is to put all the needs of the LED light up in series, which requires a high driving voltage. For example, assume that 10 to drive LED, it takes about the drive voltage to 33V. Common 5V CMOS process will not be able to achieve this IC and 40V must be of the BCD process. PAM2840 is a single chip.

          High power LED brightness can be higher, ordinary 20mA of LED only 66 mW, 1W higher the LED brightness can be given. In order to drive such 1W of LED, the company has developed a Power Analog PAM2800. It can be used four rechargeable batteries, or three ordinary dry-cell batteries, or alkaline batteries, or lithium batteries, the paper 1W of 350mA to drive LED. Most of the battery life can be maintained during the constant current LED.

And its efficiency as high as 80% -95%.

         In order to drive more powerful 3W LED, Power Analog has developed a step-PAM2801. This can be a chip on the 1st power, or two on the 1st power, or when the use of solar cells, light a 1W or 3W of LED, the feedback voltage is only 95mV, while the maximum output current can reach 1A, the highest efficiency up to 90%.

         Power Analog company is developing for a number of multi-string LED driver IC for the greater use of screen backlight.