www.austriamicrosystems.com/Power-Management/AS1390

Revision 1.04

10 - 20

AS1390A, AS1390B

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

8 Detailed Description

The AS1390 is a high efficiency, high voltage and high current DC-DC Step-up controller combined with an Step-down converter. The device is

designed for LED backlight in LCD TV-sets. The special feature is the optimized operation point for the 2D and 3D mode. Hence the output

voltage of the Step-up Converter can easily be switched via the MODE_3D pin from one voltage to the other.

Figure 18. Detailed Block Diagram Boost Converter

8.1 Boost Controller

8.1.1

Setting output voltages

The Output voltages of the AS1390 are defined by a voltage divider between the FB pin and Vout. Due to the capability of the AS1390 to switch

between two output voltages, two dividers are necessary to adjust both output voltages.

Output voltage for 2D-Mode:

Output voltage for 3D-Mode:

Where:

Note:

The overall resistance should be in the range of 100k to 200k

Ω to avoid any noise issues.

(EQ 1)

V

OUT

2D

–

V

FB

1

R

FB1

R

F B2

R

FB3

+

-------------------------------

+









×

=

(EQ 2)

V

OUT

3D

–

V

FB

1

R

FB 1

R

FB2

+

R

FB3

-------------------------------

+









×

=