AS1390A, AS1390B
Datasheet ꢀ Detailed Description
8 Detailed Description
The AS1390 is a high efficiency, high voltage and high current DCꢀDC Stepꢀup controller combined with an Stepꢀdown converter. The device is
designed for LED backlight in LCD TVꢀsets. The special feature is the optimized operation point for the 2D and 3D mode. Hence the output
voltage of the Stepꢀup 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 2DꢀMode:
RFB1
-------------------------------
VOUT – 2D = VFB × 1 +
(EQ 1)
(EQ 2)
RFB2 + RFB3
Output voltage for 3DꢀMode:
RFB1 + RFB2
-------------------------------
RFB3
VOUT – 3D = VFB × 1 +
Where: VFB = 1.25V
Note: The overall resistance should be in the range of 100k to 200kΩ to avoid any noise issues.
www.austriamicrosystems.com/PowerꢀManagement/AS1390
Revision 1.04
10 ꢀ 20
AMSCO [ AMS(艾迈斯) ]
