Features

Input voltage range: 2.7V to 5.5V

Four -channel LED drive:

#9642; Three mode Charge pump

#9642; up to 20 mAh/channel

#9642; single -line interface, easy to control

#9642; 16 123] #9642; four low -current settings as low as 50μA

#9642; low i (50 μA) in low current mode

#9642; gt; 90% Peak efficiency

Double 200 mAh LDO

#9642; User programming output: Aat 2845-EE

#9642; fixed output voltage [ 123]

aat2845

Aat2845-QI: 2.8 il and 1.8 volts Automatic soft start

overheating protection

3x4mm TQFN34-20 packaging

-40 ° C to +85 The temperature range of ° C

Application

Camera function power supply

White LED Backlight

General description

AAT2845 is a highly integrated power solution, which is suitable for single battery lithium ion LCD display applications. It includes a four -channel LED backlit driver and two integrated 200MA LDO as an additional power supply for display and camera -related chipsets.

The backlight driver is a low noise, constant -frequency charge pump DC/DC converter, using three -mode load switch (1x), scores (1.5X), and multiplier (2x) conversion to maximize increase efficiency. Each of the four channels can drive up to 20 mA.

The wire #8482; (simple serial control #8482;) serial number input is used to enable, disable and set the current of each LED, and 16 available settings are reduced to 50 μA. The low -current mode power current can be as low as 50 μA to save power and maintain high efficiency.

Each LED output is equipped with built -in short -circuit insuranceProtecting and automatic disable functions. The built -in soft startup circuit prevents excessive wave current during startup. The low -current shutdown function can be disconnected from the input terminal and reduce the static current to less than 1 μA.

AAT2845 provides lead -free heat enhancement of 20 stitches 3x4mm TQFN packaging.

Typical application

The typical value is TA 25 ° C.

Figure Figure Function description AAT2845 is an integrated LCD display application solution, which built up a driver for white LED backlight and two LDO voltage regulator for logical power supply.

Backlight drive is a three -mode load switch (1x) and high -efficiency (1.5X or 2X) charge pump equipment. In order to maximize the power conversion efficiency, the internal sensing circuit monitor the voltage required for the input of each constant current receiver, and set the load switch and the charge pump mode according to the input voltage and current receiver input voltage. As the battery discharge time is pushed, when any of the four current receivers input is close to disconnection, the charging pump is enabled. The oil supply pump was initially launched in 1.5X mode. If the output of the charge pump is reduced to the approach of any current source output, the charge pump will be automatically converted to the 2X mode. The charge pump only requires four external components: two 1 μF ceramic capacitors for charge pump flight capacitors (C and C), a 1 μF ceramic input capacitor (C), and a 0.33μF to 1 μF ceramic charge pump output capacitor (C).

Four constant current receivers input (D1 to D4) can drive four separate LEDs, and the maximum current of each LED is 20 mAh. The input of the unused receiver must be connected to the output pin; otherwise, the component will work in the 2X charging pump mode. The scwire serial interface enables the charge pump and sets the amplitude of the current.