EV-122 - Skyworks Solutions, Inc.

EV-122
AAT3175 EVAL: High Efficiency 1X/1.5X/2X
Charge Pump For White LED Flash Applications
Introduction
The AAT3175 EVAL board demonstrates the functionality of the AAT3175 and its application as a white LED
flash driver. The AAT3175 is a low-noise, constant frequency charge pump DC/DC converter with tri-mode load
switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency and operate over a wide
input voltage range.
The AAT3175 is programmable with AnalogicTech’s S2Cwire™ (Simple Serial Control™) serial interface and
has four independent, constant current LED channels. LED constant current levels are set according to a 16level logarithmic scale. The device is able to achieve a flash current level of 300mA while requiring only 1µF
capacitors.
This document describes the evaluation board and its accompanying user interface. A brief “Getting Started”
section is also included to help the user begin operating the evaluation board. A schematic of the complete
circuit appears in Figure 1; Figures 2 and 3 depict the actual board layout. For additional information, please
consult the AAT3175 product datasheet.
Schematic
DC+
DC-
J1
DC+
U1
AAT3175
C1
1µF
1
2
3
4
5
6
C3
1µF
D4
EN/SET
C1+
C1VOUT
C2+
D3
D2
D1
GND
VIN
C2-
12
11
10
9
8
7
JPx
C4
1µF
C2
1µF
GND
D1
GND
R7
220
J2
R6
100K
DC+
GND
R3 R2
1K 1K
DATA
0
2
4
SW3
1
3
5
FLASH
0
2
4
MOVIE
0
2
4
SW2
1
3
5
R1
1K
C5
10µF
U2
1
2
3
4
VDD
GP5
GP4
GP3
PIC12F675
VSS
GP0
GP1
GP2
8
7
6
5
VR4
POT 10K
R4
330
SW1
1
3
5
GND
R5
330
LED7
RED
GND
LED0
GRN
GND
GND
Figure 1: AAT3175 Evaluation Board Schematic.
EV-122.2005.10.1.0
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EV-122
AAT3175 EVAL: High Efficiency 1X/1.5X/2X
Charge Pump For White LED Flash Applications
Getting Started
The board has two terminals labeled DC- and DC+ for the input power supply connection. A jumper is inline
with the supply bus for connecting/disconnecting power (J1). To apply power to the board, connect the supply
by jumpering ON, MCU; the red LED7 should illuminate, indicating that power has been connected to the
board. There is an additional jumper labeled ON SRL OFF, which provides access to EN/SET. For operation
with the accompanying microcontroller and user interface, ensure that the jumper is in the ON SRL position.
The user interface is provided by three buttons: DATA, FLASH, and MOVIE. The modes of operation are
detailed in Table 1. The DATA button increments the data setting until reaching 16, at which point it wraps back
to 1. Use the DATA button to set the current for flash and movie modes. As an example, pressing the DATA
button 4 times will set the microcontroller to use 5 EN/SET edges for flash or movie (the default of 1, plus 4
gives 5). Pushing the FLASH button will release a flash pulse. The current level for the flash pulse is determined by the data setting. The duration of the flash pulse is determined by the trim pot VR4. The flash pulse
duration can be set from 10ms to 2 seconds by adjusting VR4. The MOVIE button toggles the device on and
off. The current level is also determined by the data setting. To reset the microcontroller, press all three buttons together and then release them. The data setting will be reset back to 1. To see the effect of each current
level step, enable the device with the MOVIE button and then use the DATA button to traverse the 16 settings
with the LED on.
User Interface Functionality
Button(s) Pushed1
DATA
Description
Increments through the 16 data settings. Hold down to auto-cycle. (Does not
turn light on; just sets DATA.)
FLASH
Generate flash pulse. Current level determined by DATA setting. Duration
determined by trim pot VR4 (adjustable from 10ms to 2 sec).
MOVIE
Toggle the device ON/OFF. Current level determined by DATA setting.
CYCLE + UP + DOWN
Reset.
Table 1: User Interface Functionality.
1. The '+' sign indicates that these buttons are all pressed and released together.
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EV-122.2005.10.1.0
EV-122
AAT3175 EVAL: High Efficiency 1X/1.5X/2X
Charge Pump For White LED Flash Applications
Printed Circuit Board
Figure 2: AAT3175 Evaluation Board Top Layer (not to scale).
Figure 3: AAT3175 Evaluation Board Bottom Layer (not to scale).
EV-122.2005.10.1.0
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EV-122
AAT3175 EVAL: High Efficiency 1X/1.5X/2X
Charge Pump For White LED Flash Applications
AAT3175 EVAL Component Listing
Component
Part Number
U1
AAT3175
U2
PIC12F675
D1
R1-R3
C1-C4
J1, J2
LED0
LED7
C5
R4, R5
R6
R7
JPx
JP7, JP8
VR4
SW1-SW3
Description
LMFLC4500
Chip Resistor
GRM188R61A105KA93D
PRPN401PAEN
CMD15-21UGC/TR8
CMD15-21SRC/TR8
GRM31CR70J106KA01L
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
EVN-5ESX50B14
PTS645TL50
High Efficiency 1X/1.5X/2X CP for
White LED; TDFN33-12 Package
8-Bit CMOS, FLASH-based µC;
8-Pin PDIP Package
4-Die, 2-Pin, High Luminosity LED
1KΩ, 5%, 1/4W; 1206
1µF, 10V, X5R, 10%; 0603
Connecting Header, 2mm Zip
Green LED; 1206
Red LED; 1206
10µF, 6.3V, X7R, 10%; 1206
330Ω, 5%, 1/4W; 1206
100KΩ, 5%, 1/4W; 1206
220Ω, 5%, 1/4W; 1206
0Ω, 5%; 0603
0Ω, 5%; 0805
10K POT; 3mm Squared SMD
Switch Tact, SPST, 5mm
Manufacturer
AnalogicTech
Microchip
Lumimicro
Vishay
Murata
Sullins Electronics
Chicago Miniature Lamp
Chicago Miniature Lamp
Murata
Vishay
Vishay
Vishay
Vishay
Vishay
Panasonic-ECG
ITT Industries
Table 2: Component Listing.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work
rights, or other intellectual property rights are implied.
AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice, and advise customers to obtain the latest
version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and
other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
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EV-122.2005.10.1.0