EVALUATION BOARD DATA SHEET

EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Introduction
The AAT1278 evaluation board demonstrates the functionality of the AAT1278 and its application as LED photo flash
driver under Skyworks' AS2Cwire serial digital interface control.
The AAT1278 is a boost converter with a programmable constant current LED driver with an input voltage range of
2.7V to 5.5V. The single flash LED driver delivers up to 1500mA output current in flash mode. An external resistor is
employed to set the flash LED maximum current for flash and movie modes; the movie mode LED current can be easily programmed from 100% to 0% of the maximum current value in 16 steps with a single GPIO output via the
AS2Cwire interface; the flash to movie mode ratio can also be easily programmed from 2:1 to OFF in 16 steps with a
single GPIO output via the AS2Cwire interface and the fixed flash to movie mode ratio is 7.3:1.The wide input voltage
range, small solution size, and high switch frequency is suitable for small battery-powered applications. This document
describes the evaluation board and its accompanying user interface. A “Getting Started” section is included to help the
user to begin operating the evaluation board. The AAT1278 evaluation board is shown in Figure 1; Figures 2 and 6
depict the board schematic and layout. For additional information, please consult the AAT1278 product datasheet and
application note (AN-111) for understanding of the AS2Cwire serial digital interface.
Board Pictures
(a) Top Side.
(b) Bottom Side.
Figure 1: AAT1278 Evaluation Board Picture.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
1
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Board Schematic
GND
VIN
JP1
R3
MCU
R5
10K
0
Movie Mode Control
Flash/Movie Mode Current Ratio
FLEN
0
0
R6
10K
R7
10K
U2
1
2
3
4
SW1
2
4
1
3
5
SW2
2
4
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
PIC12F675
1
3
5
8
7
6
5
FLINH
2
4
SW4
1
3
5
JP2
C3
1µF
R10
100k
R8
330
R9
330
R4
100k
(opt)
VOUT
LED1
RED
LED2
GRN
SW3
2
4
0
10k
D1
1
3
5
U1
JP3
EN/SET
A3
A1
C1
A2
R2
100K
B2
A4
C4
NA
C1
2.2µF
AGND
EN/SET
FL
FLEN
IN
PGND
RSET
FLGND
B1
C2
FLINHIBIT
SW
SW
OUT
C3
B3
B4
C4
L1
1µH
AAT1278 CSP-12
R1
133k
C2
2.2µF
Figure 2: AAT1278 Evaluation Board Schematic.
Getting Started
The board has two terminals labeled VIN and GND for the input power supply connection. Jump the JP1 to connect the
VIN power to microcontroller VDD and AAT1278 IN. Jump JP2 to connect the SW4 to AAT1278 FLINHIBIT pin for inhibiting flash current. Jump the JP3 to set the microcontroller to generate AS2C code signal for driving LED. After all jumpers are in the correct positions, apply power between 2.7V and 5.5V to the VIN and GND terminals to power the
AAT1278 (U1) and microcontroller (U2); the red LED (LED1) should illuminate when the microcontroller is powered.
The green LED (LED2) should flicker when microcontroller sends the AS2C digital signal to AAT1278.Table1 shows the
jumps’ function, Figure 3 shows the connection of the AAT1278 board.
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Jumper Name
JP1
JP2
JP3
Description
Jump JP1 MCU ON position to power on the microcontroller and AAT1278, Jump JP1 MCU OFF position
to disconnect the power.
Connect JP2 to active the Flash Inhibit function by push SW4.
Jump JP3 low position to generate AS2C code signal from microcontroller to AAT1278, Jump JP3 high
position to cut off the AS2C signal between microcontroller and AAT1278.
Table 1: Jumpers’ Function Description
Figure 3: AAT1278 Evaluation Board Demonstration Connection.
User Interface Functionality
The user interface is provided by four push buttons: MMC (SW1), FMM (SW2), FLEN (SW3) and FLINH (SW4). A summary of operational modes for each button is outlined in Table 2.
Definition of Each Control
• MMC—Movie Mode Control (SW1): Sets movie mode current. Each switch closure will incrementally decrease the
movie mode current stating at 100% to 0% (off) in 16 steps. Refer to the AAT1278 datasheet for detailed explanations
of movie mode operation.
• FMM—Flash/Movie Mode Current Ratio Control (SW2): Sets Flash/Movie Mode Current Ratio. Each switch closure will
incrementally decrease the flash/movie mode current ratio stating at 2:1 to 0% (off) in 16 steps. Refer to the AAT1278
datasheet for detailed explanations of Flash to Maximum Movie Mode Current Ratio operation.
• FLEN—Manual Flash Enable (SW3): Initiates a flash of maximum flash current.
• FLINH—Inhibit Flash (SW4): Inhibit a flash current into default movie-mode current level
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
3
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Button(s)
SW1(MMC)
SW2(FMM)
SW3(FLEN)
SW3(FLEN)+SW4(FLINH)
Description
[Push/Release once per step] Movie mode LED current dimming control. Each switch closure will issue
an AS2C command to increment the data of the movie mode current register bits There are 16 steps
in this register to step movie mode current from full scale to off (refer to the AAT1278 product datasheet for additional information).
[Push/Release once per step] Flash/Movie Mode Current Ratio Control. Each switch closure will issue
an AS2C command to increment the data of the Flash/Movie Mode Current Ratio register bits There
are 16 steps in this register to step Flash/Movie Mode Current Ratio from 2:1 to off (refer to the
AAT1278 product datasheet for additional information).
[Push/Release once] Flash enable. Manually enables the AAT1278 boost converter to get the maximum flash current, initiates a single flash pulse.
[Push SW4 and hold, then Push/Release SW3 once] Flash inhibit. Manually inhibit a flash current and
enables the AAT1278 boost converter to get the maximum movie mode current, initiates a single flash
pulse.
Table 2: User Interface Functionality.
LED Drive Current Set-Up
LED Drive Current
The AAT1278 can be set up to provide 1.5A maximum flash mode current. The maximum flash mode current is set by
R1 and can be set to 107kΩ for a maximum flash LED drive current of 1.5A. In this AAT1278 manual’s application R1
is set to 133kΩ for 1.2A maximum flash current. Flash current can be calculated using Equation1 by change the value
of R1. Refer to the AAT1278 datasheet to program a desired flash current, the default maximum Movie Mode Current
can be calculated using Equation2 in this AAT1278 manual.
IFL =
162kΩ ∙ A
R1
1200mA
IMOVIE MODE = IFL(FL to MM Ratio) =
7.3
= 164.4mA
AS²Cwire Interface and Control
JP3 connects GPIO (U2) and AAT1278 (U1) AS2Cwire interface EN/SET, AS2Cwire interface data is programmed by the
microcontroller U2 and its associated push button function switches SW1, SW2. The movie current can be programmed
from 100% to 0% of the maximum movie mode current in 16 linear steps controlled by AS2Cwire data signal as shown
in Table 3.The flash to movie mode ratio may be varied from 2:1 to OFF in 16 linear steps controlled by AS2Cwire data
signal as shown in Table 4, the default ratio between the flash current level and maximum movie mode current level is
7.3:1.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Data
Percentage of Maximum MM Current
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
100%
89%
79%
71%
63%
56%
50%
45%
40%
36%
32%
28%
25%
22%
20%
0%
Table 3: Movie Mode (MM) Current Programming.
Data
Flash to Movie Mode Ratio
1
2
3
4*
5
6
7
8
9
10
11
12
13
14
15
16
2:1
3.8:1
5.5:1
7.3:1
8.9:1
10.5:1
12.2:1
13.8:1
14.9:1
16.5:1
18:1
19.6:1
21.1:1
22.6:1
24:1
OFF
Table 4: Flash/Movie Mode Current Ratio.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
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EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Test Waveform
Movie Mode Waveform
Figure 4 shows the waveform under movie mode controlled by AS2Cwire with data code 5.The IOUT rises to 100mA (63%
of maximum movie mode current) as expected.
Figure 4: Movie Mode Current Controlled by AS2Cwire Data
(Ch1: VOUT; Ch2: EN/SET; Ch3: IIN; Ch4: IOUT).
6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Maximum Flash Current Waveform
Figure 5 shows the AAT1278 Flash Current waveform with a FLEN pulse. IOUT maintains 1.2A when the flash enable
pulse is asserted.
Figure 5: Flash Current Operation with FLEN Pulse
(Ch1: VOUT; Ch2: FLEN; Ch3: IIN; Ch4: IOUT).
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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7
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Maximum Movie Mode Current Waveform
Figure 6 shows the AAT1278 Maximum Movie Mode Current waveform with a FLINH pulse, while FLEN is keeping high.
IOUT maintains 164mA when the FLINH pulse is asserted.
Figure 6: Complete Flash current operation waveform
(Ch1: FLINH pulse; Ch2: FLEN; Ch4: IOUT).
8
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Printed Circuit Board
(a) Top Layer.
(b) Bottom Layer.
Figure 6: AAT1278 Evaluation Board.
AAT1278 EVAL Component Listing
Component
Part Number
U1
U2
SW1 – SW4
R1
R2, R4, R10
R3, R5, R6, R7
R8, R9
C1, C2
C3
C4(No Mounted)
L1
LED1
LED2
JP1, JP2, JP3
D1
AAT1278
PIC12F675
PTS645TL50
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
GRM188R71A225KE15
GRM188R71C105K
SD3812-1R0-R
0805KRCT
0805KGCT
PRPN401PAEN
FCW401Z4
Description
1.5A Step-Up Current Regulator for Flash LED;
8-Pin FLASH-Based 8-Bit CMOS Microcontrollers
Switch Tact, SPST, 5mm
133kΩ, 1%, 1/4W,0402
100kΩ, 1%, 1/4W,0603
10kΩ, 5%, 1/4W,0603
330Ω, 5%, 1/4W,0603
2.2μF, 10V, X7R, 0603
1μF, 16V, X7R, 0603
Drum Core, 1μH, 2.69A, 48mΩ
Red LED,0805
Green LED,0805
Conn. Header, 2mm zip
White Flash LED
Manufacturer
Skyworks
Microchip
ITT Industries
Vishay
MuRata
Cooper Bussmann
HB
Sullins Electronics
Seoul Semiconductor
Table 5: AAT1278 Evaluation Board Bill of Materials.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
9
EVALUATION BOARD DATA SHEET
EV193
Evaluation Board for the AAT1278 1.5A Single Flash LED Driver
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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10
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012