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AS3490

Datasheet - D e ta i l e d D e s c r i p t i o n

8 Detailed Description

The AS3490 is a high performance DCDC step up converter and three current sources in a small WL-CSP12 package.

The LED configuration is done in up to three strings

in excellent application efficiency even using very small external components (capacitors and coil). The device is con-

trolled by ON. A high levels on this input enables the DCDC and the current sources. ON can be used as PWM input

3

to accurately control the LED brightness.

The target application is to use the AS3490 for highly efficient backlight driver (display and/or keypad backlight).

Internal Circuit

Figure 16. AS3490 internal circuit

The AS3490 includes a fixed frequency DCDC step-up with accurate startup control. It is enabled by the input pin ON

and controls the LED current with five current sources. These input can be used as PWM inputs to control the bright-

ness:

- a high level on ON enables LED1, LED2 and LED3

1. Unused strings shall be connected to VOUT or GND.

2. Single LED strings can be mixed with dual LED strings as long as one string has two LEDs in series - it will

reduce application efficiency.

3. Using the PWM inputs, the AS3490 supports DLS, dynamic luminance scaling, also called CABC, content

adaptive backlight control or DBC, dynamic backlight control.















 

  







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AS3490