MAX8631X driving white LED circuit diagram

The MAX8631X charge pump can drive up to 8 white LEDs with constant current and achieve uniform brightness. It can drive each main screen white LED (M1~M4) with a current of up to 30mA for backlighting. The white LEDs (F1~F4) used in the flash are individually controlled, and the MAX8631X can drive each white LED at up to 100mA (or a total current of 400mA). Two on-chip 200mA LDOs power each module of the camera. The output voltage pins of the two LD0s are programmable to meet the requirements of different camera modules. Utilizing adaptive 1x mode, 1.5x mode, 2x mode charge pump and ultra-low dropout current regulator, the MAX8631X is able to achieve high efficiency over the entire effective voltage range of a single-cell Li-ion battery. Because it has a fixed switching frequency of 1MHz, it can use tiny external components. Its optimized regulation scheme ensures low EMI and low input ripple.

(1) Main technical characteristics of MAX8631X charge pump

The main technical characteristics of the MAX8631X charge pump are as follows.

①Can drive up to 8 white LEDs.

②30mA drive current for backlight.

③ 400mA total drive current for flash.

④Two built-in low-noise 200mA LDOs.

⑤ Within the effective power supply voltage range of lithium-ion batteries, the maximum efficiency of 94% and the average efficiency of 85% can be maintained (η=PLED/PABT).

⑥0.2% current matching accuracy.

⑦ It has adaptive switching function of 1x pressure mode, 1.5x pressure mode and 2x pressure mode.

⑧Flexible brightness control.

⑨Single-wire, serial pulse interface (level 32).

⑩2-bit logic (3 levels).

(11) Overheating derating protection function.

(12) Low input ripple and low EMI.

(13) Input voltage range of 2.7~5.5V.

(14) It has soft start, overvoltage and thermal shutdown protection.

(15) Adopts 28-pin, 4mm×4mm thin QFN package (maximum height 0.8mm).

(2)Typical application circuit

The MAX8631X charge pump drives white LED circuit as shown in the figure.

Figure MAX86l3X ​​charge pump driving white LED circuit