AATIAN63 Datasheet, PDF (1/4 Pages) SiGe Semiconductor, Inc. – High Current High Efficiency Charge Pump

EV-128
AAT3174 EVAL: High Current,
High Efficiency Charge Pump
Introduction
The AAT3174 EVAL board demonstrates the functionality of the AAT3174 and its application as a high current
white LED flash driver. The device consists of a tri-mode charge pump with load switch (1X), fractional (1.5X),
and doubling (2X) conversion modes to provide excellent efficiency for both flash and movie modes. The LED
drive current is programmable in 16 steps through the Simple Serial Control™ (S²Cwire™) interface. An exter-
nal set resistor determines the maximum LED drive current and it can be set up to 800mA. By default, the eval-
uation board is set to 600mA maximum LED drive current.
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 actual board layout is also provided. For additional information,
please consult the AAT3174 product datasheet.
Schematic
DC-
DC+
J1
DC+
GND
C4
4.7µF
C1
GND 1µF
U1
AAT3174
1
2
3
4
5
6
VIN
C1+
C1-
GND
F1
RSET
VIN
VOUT
C2+
C2-
N/C
EN/SET
12
11
10
9
8
7
R8
187K
R8 = 187K
D1
GND ^{for 600mA}
C3
C2
2.2µF
1µF
GND
Uses a single flash LED
Lumileds LXCL-PWF1 or
Lumimicro LMPTWH556S
Not both
R6
100K
J2
GND
R7
220K
DATA 0
24
FLASH ₀
24
MOVIE 0
24
SW3
135
SW2
135
SW1
135
R3 R2 R1
1K 1K 1K
GND
U2
1
2
3
4
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
8
7
6
5
PIC12F675
DC+
C7
1µF
VR4
POT10K
R5
330
LED7
RED
R4
330K GND
GND
LED0
GRN
GND
Figure 1: Evaluation Board Schematic
EV-128.2006.04.1.0
1