AATIAN36 Datasheet, PDF (1/7 Pages) SiGe Semiconductor, Inc. – Step-Up DC/DC Converter

EV-130
AAT1231 EVAL: Step-Up DC/DC Converter
for White LED Backlight Applications
Introduction
The AAT1231 is a high frequency, high efficiency constant current boost converter driving up to six white LEDs
in series or up to twelve white LEDs in parallel/series configuration. The input voltage is 2.7V to 5.5V, which
is ideal for portable devices powered by single-cell lithium-ion/polymer (Li-ion) batteries. With over-voltage pro-
tection and dynamically-programmable voltage control via AnalogicTech’s patented Simple Serial Control™
(S²Cwire™) interface, the AAT1231 is an ideal choice for white LED backlight applications.
The AAT1231 evaluation board provides a platform for test and evaluation of the AAT1231 for white LED back-
light applications driving six LEDs. The AAT1231 is programmable with the S²Cwire interface, using an
onboard microcontroller which is capable of brightening and dimming the LEDs in 26 discrete steps. The
SELECT logic signal from the microcontroller provides a stepped load from 1.5x to 3.0x of nominal output cur-
rent, depending on the S²Cwire data register (default = 3.0x).
This document describes the evaluation board and its accompanying user interface. In addition, a brief
"Getting Started" section is included to help the user begin operating the evaluation board. A schematic of the
complete circuit is shown in Figure 1. The board layout is also provided. For additional information, please
refer to the AAT1231 product datasheet.
Schematic
VCC
R8
330
D7
RED
R7 R6 R5
1K 1K 1K
Up
Down
Select
SW3
0 ₂₄
135
SW2
02 ₁
43
5
SW1
0 ₂₄
135
R4
10K
C3
U2
1µF
1
2
3
4
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
8
7
6
5
PIC12F675
DC- DC+
J2 J3
J1
1
2
3
VCC
JP1
C1
2.2µF
U1
1
2
3
4
5
6
VIN
EN
SEL
VP
N/C
SW
AAT1231
LIN
OVP
FB
GND
PGND
SW
12
11
10
9
8
7
R9
330
D8
GREEN
(Select indicator)
L1
2.2µH
DS1
Schottky
R2
226K
R3
12K
R1
30.1Ω
D6 D5
LED LED
VOUT
D1
LED
D2
LED
D3
LED
C2
2.2µF
D4
LED
Figure 1: AAT1231 Evaluation Board Schematic with Six White LEDs and Microcontroller.
EV-130.2006.08.1.0
1