202290A.pdf

EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
Introduction
The AAT2869 EVAL board demonstrates the functionality of the AAT2869 and its application as backlight driver and
dual LDO outputs.
The AAT2869 is a low-noise, constant-frequency charge pump DC/DC converter that uses a dual-mode load switch (1x)
and fractional (1.5x) conversion to maximize efficiency for white LED applications. The AAT2869 is capable of driving
4 white LEDs at a total 124mA and two 150mA low dropout (LDO) linear regulators from a 2.7V to 5.5V input. The
fade-in/fade-out feature makes backlight turn-on/turn-off more visual comfortable. All these functions can be
programmed via the AS2Cwire™ interface.
Skyworks' AS2Cwire™ serial digital input is used to enable, disable and set the maximum LED current to one of 32
levels for the LEDs. Each LED current ranges from 31mA to 0.4mA. LED current fade in/fade out is also enabled and
disabled by writing registers through the interface. Regardless of the backlight setting, LDOs enable, disable and output voltage levels are also programmed through the interface. There are five output voltage levels and sixteen combinations of LDOA and LDOB.
This document describes the evaluation board and its accompanying user interface. A brief “Getting Started” section
is also included to help the user to begin operating the evaluation board. A real board picture appears in Figure 1.
Figures 2 and 5 depict the board schematic and layout. Figure 4 shows the usage of the three buttons on the EVAL
board. For additional information, please consult the AAT2869 product datasheet.
Board Picture
(a) Top Side
(b) Bottom Side
Figure 1: AAT2869 Evaluation Board Picture.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
1
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
Evaluation Board Schematic
U1
AAT2869
C1
1µF
J1
1
18
7
6
DC+
V_LDO
CIN
2.2µF
DC-
8
V _MCU
4
AAT2869
White LED
Driver
R8
50k
C2
1µF
16
15
17
VOUT
COUT
1µF
R1
0
D1
R2
0
R3
0
R4
0
D3
D2
D4
EN/SET
GND
9
FCAP
5
AGND EP
D1
D2
D3
D4
LDOA
LDOB
10
11
12
13
3
LDOA
2
LDOB
CLDOB
2.2µF
CLDOA
2.2µF
EN/SET
R10 R11 R12
1k
SELECT
C2+
C2OUTCP
GND
14
CF
1µF
C1+
C1IN
INLDO
1k
1k
1
2
3
4
U2
VDD
GP5
GP4
GP3
PIC12F675
VSS
GP0
GP1
GP2
C3
0.1µF
8
7
6
5
R9
1k
LED2
Red
R6
1k
DETAIL
LED1
Green
SEND
AS2Cwire
Microcontroller
Figure 2: AAT2869 Evaluation Board Schematic.
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
Getting Started
The board has two terminals labeled DC+ and DC- for the input power supply connection. Set J1 to the left position,
jump the V_MCU, and apply 2.7V to 5.5V power to the DC+ and DC- terminals to power the AAT2869 (U1) and microcontroller (U2); the red LED (LED2) should illuminate when the microcontroller is powered. The EN/SET option provides
access to the microcontroller program. Jump EN/SET when using a microcontroller program to generate AS2Cwire data
for the AAT2869. Figure 3 shows the connection of the board.
Figure 3: AAT2869 Evaluation Board Demonstration Connection.
The three buttons on the AAT2869 evaluation board are used to set address and data of the registers and send the
selected address and data to the AAT2869 through the EN/SET signal line. The functions of the three buttons are illustrated in Figure 4.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
3
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
Button Functions
Three buttons are located on the evaluation board: SELECT, DETAIL and SEND. The SELECT button is used to select the
register address. Each press of the button selects one register address from 0 to 5 then wraps back to 0. The DETAIL
button is used for data select for a particular address register. The SEND button sends the selected address and data
to the EN/SET signal line. Figure 4 details the button functions.
SELECT
Button
DETAIL
Button
Three
Button
Functions
Pressed times Register Addr.
0
Backlight Enable
1
1
Backlight Floor Level
2
2
Backlight MSB
3
3
Backlight LSBs
4
5
4
5
LDO Enable/Disable
LDO Output Voltage
Selected Register
Pressed times
Detail selected
Addr. 0
0
Backlight On
Addr. 1
Addr. 2
Addr.3
Addr. 4
Addr. 5
SEND
Button
Register Function
0
1
Backlight On
2
Backlight On, Fade Out On
3
Backlight On, Fade In On
4
Backlight Off
0
Backlight Floor: 0.5mA
1
Backlight Floor: 1.0mA
2
Backlight Floor: 2.0mA
3
Backlight Floor: 3.0mA
0
BL[4] = 0
1
BL[4] = 1
0
BL[3~0] = 0000
1
BL[3~0] = 0001
15
BL[3~0] = 1111
0
LDOA off, LDOB off
1
LDOA off, LDOB on
2
LDOA on, LDOB off
3
0
LDOA on, LDOB on
LDOA=3.0V LDOB=2.8V
1
LDOA=3.0V LDOB=1.8V
2
LDOA=3.0V LDOB=1.5V
3
LDOA=3.0V LDOB=1.2V
4
LDOA=2.8V LDOB=2.8V
5
LDOA=2.8V LDOB=1.8V
6
LDOA=2.8V LDOB=1.5V
7
LDOA=2.8V LDOB=1.2V
8
9
LDOA=1.8V LDOB=2.8V
LDOA=1.8V LDOB=1.8V
10
LDOA=1.8V LDOB=1.5V
11
LDOA=1.8V LDOB=1.2V
12
LDOA=1.5V LDOB=2.8V
13
LDOA=1.5V LDOB=1.8V
14
LDOA=1.5V LDOB=1.5V
15
LDOA=1.5V LDOB=1.2V
Send Selected Address and Data through EN/ SET Signal Line
Figure 4: Button Functions of the AAT2869 Evaluation Board.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
LED Current Control
AS2Cwire Interface
The LED current can be programmed from 0.4mA to 31mA in 32 steps through the AS2Cwire interface. Addresses 3
and 2 with 5 bits from BL[0] to BL[5] are adopted to set the LED current value as shown in Table 1.
Addr2
Addr3
LED Current Codes
BL4
BL3
BL2
BL1
BL0
LED Current (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0.4
0.9
1.9
2.9
3.9
4.9
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0 [Default]
21.0
22.0
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
Table 1: AAT2869 Maximum LED Current Register Settings.
The LED current is changed to the programmed value only after the “Backlight LSBs” register is written. For example,
to change the LED current setting from the default setting of 20mA to 31mA, the steps are listed as below.
1.
2.
3.
4.
5.
6.
Press
Press
Press
Press
Press
Press
the
the
the
the
the
the
SELECT button to select the address 2 “Backlight MSB” register.
DETAIL button to set BL[4] to 1.
SEND button to send the selected address and data through the EN/SET pin to the AAT2869.
SELECT button to the select address 3 “Backlight LSBs” register.
DETAIL button to set BL[3~0] to 1111.
SEND button to set each LED to 31mA of LED current.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
5
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
LED illumination can be turned off directly from the programmed maximum value to zero from the programmed maximum LED current to the set floor gradually using the fade-out function. The default floor is 0.5mA. When using the
fade-in or fade-out function, the floor value and LED maximum current value should be set before fade-in or fade-out
is enabled. If no LED maximum current and floor value are set, 20mA and 0.5mA are the default LED current maximum
and floor level when fade-in or fade-out is enabled.
LDO Control
The AAT2869 has two LDOs: LDOA and LDOB. The LDOs’ enable, disable, and output voltage values are controlled by
writing registers through the AS2Cwire interface. Figure 4 shows how to use the three buttons on the evaluation board
to select and send LDO settings.
Printed Circuit Board
(a) Top Layer
(b) Bottom Layer
Figure 5: AAT2869 Evaluation Board Layout.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
EVALUATION BOARD DATA SHEET
EV172
Evaluation Board for the AAT2869
Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs
AAT2869 EVAL Component List
Component
Part Number
Description
Manufacturer
U1
U2
R1, R2, R3, R4
R7, R8
R6, R9, R10, R11, R12
C1, C2, COUT
CIN, CLA, CLB
C3
CF
D1, D2, D3, D4
LED1
LED2
CYCLE, UP, DOWN
AAT2869IDT-T1
PIC12F675
RC0603FR-070RL
RC0603FR-0749K9L
RC0603FR-071KL
GRM188R71C105K
GRM188R61A225K
GRM188R71C104K
GRM188R71C563K
RS-0805UW
0805KGCT
0805KRCT
6*6*5
High Efficiency, 4 Channel Backlight Driver with Dual LDOs
8-Pin Flash-Based 8-Bit CMOS Microcontrollers
Res 0Ω 1/10W 1% 0603 SMD
Res 49.9KΩ 1/10W 1% 0603 SMD
Res 1KΩ 1/10W 1% 0603 SMD
Cap Ceramic 1μF 0603 X7R 16V 10%
Cap Ceramic 2.2μF 0603 X5R 10V 10%
Cap Ceramic 0.1µF 0603 X7R 16V 10%
Cap Ceramic 0.056μF 0603 X7R 16V 10%
20mA White LED 0805
Green LED 0805
Red LED 0805
12V 50mA Pushbutton
Skyworks
Microchip
Yageo
Murata
Realstar
HB
HB
E-LT
Table 2: AAT2869 Evaluation Board Component List.
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012
7