EVALUATION BOARD DATA SHEET

EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Introduction
The AAT2870 evaluation board demonstrates the functionality of the AAT2870 and its application as a white LED
driver under PWM control.
The AAT2870 is a highly integrated charge pump-based lighting management unit (LMU) providing eight independently configurable LED channels that can also be grouped into main or sub backlight controls. The built-in support for
low cost ambient light sensors automates all brightness adjustments. In addition, four programmable low dropout
(LDO) linear regulators are provided to supply other lighting and camera module functions. The LMU is optimized for
single-cell lithium-ion/polymer systems, which makes it ideal for portable devices.
High frequency PWM dimming for both Main and Sub display backlighting is provided and is compliant with Content
Adaptive Brightness Control (CABC) specifications with a PWM frequency up to 100 kHz.
All functions of the AAT2870 are programmed using an industry standard bi-directional I2C interface. We provide a
Windows GUI program to build the I2C connection between the computer and the AAT2870 evaluation board.
This document describes the evaluation board and its accompanying useful interface. In addition, a brief “Getting
Started” section is included to help user begin operating the evaluation board. The actual evaluation board is shown in
Figure 1. The schematic of the complete circuit is shown in Figure 2.
For detailed information, please consult the AAT2870's product datasheet.
Board Pictures
(a) Top Side.
(b) Bottom Side.
Figure 1: AAT2870 Evaluation Board Pictures.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
1
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Board Schematic
R11
0
TP1
D1 D2 D3 D4 D5 D6 D7 D8
VIN
F1
BL8
E2
BL7
F2
E3
BL5
E4
BL4
F4
BL3
BL2
BL1
BL6
LDOC
AMB_IN
AGND
P5
SCL
1
2
3
4
5
6
7
8
9 10
GND
SDA
3
2
1
A4
A1
LDOA
B1
LDOB
B2
LDOC
A2
LDOD
C11
10nF
LDOB
C4
2.2µF
TP4
LDOC
C8
2.2µF
A3
C9
2.2µF
E1
TP5
LDOD
TP6
TP9
VIN
TP3
C2
4.7µF
AMB_IN
SBIAS
P2
LDOA
SBIAS
GC2
AMB_IN
C1
B3
TP8
C2
EN
SBIAS
AGND
FLTR
C2BC_M
LDOD
SDA
C2+
D1
GND
AAT2870
SDA C3
GND
LDOB
R9
100K
Enable
TP7
C4
D2
C1+
SCL
VIN
3
2
1
LDOA
C5
P1
B5
C3
NP
NEG
C1-
TP2
VIN
U1
IN_LDO
PGND
C7
0.22µF
B4
D4
IN
F3
C6
0.22µF
A5
D5
SCL D3
C5
2.2µF
PGND
VIN
F5
C1
2.2µF
E5
R1 R2 R3 R4 R5 R6 R7 R8
0
0
0
0
0
0
0
0
C10
2.2µF
1
R10
(open)
2
R12
3
0
BC_M
U2
OUT GC2
GND GC1
VCC
NC
6
SBIAS
GC1
BH1600FVC
Header 5x2
Figure 2: AAT2870 Evaluation Board Schematic.
2
1
2
3
GC2
5
4
P3
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
P4
1
2
3
GC1
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
I2C USB Communication Board
The AAT2870 adopts I2C protocol to control 39 Registers. In order to visit the registers more conveniently, a Windows
GUI and an USB interface board are provided. The USB interface board is to convert data and clock signal from USB
protocol to I2C protocol to control the AAT2870. The USB interface board can be one of the figures as shown in Figure
3. The following section “Windows GUI” shows more information about the program.
(a) AATI USB Interface Board.
(b) AATI USB Module Board.
Figure 3: AATI I C USB Interface Board Pictures.
2
The USB interface board has two communication ports for connections: Mini-USB port is for connecting to PC USB, and
5 x 2 header port is for connecting to the 5 x 2 header (P5) on the AAT2870 evaluation board by a 10 flat cable. Figure
4 shows the two ports of the two boards and any one of the I2C USB boards shown can be used.
Figure 4: I2C USB Board Connection.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
3
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Getting Started
In order to use the AAT2870 evaluation board, we need to configure the hardware and software in the first instance.
The section of “Board Configure and Connection” is for hardware setup. The section of “Windows GUI” is for software
setup.
Board Configuration and Connection
The AAT2870 has PWM backlight control which needs external PWM signal to demonstrate. Figure 5 shows the typical
connections with external PWM signal source. 100% or 0% PWM duty control can be realized by Jumper P2 without
external PWM signal source. Table 1 highlights the steps for configuring the board and making the correct connections
to the appropriate test equipment.
Step
Step1:Configure the
AAT2870 EV board.
Step2: Make connections
between PC and AAT2870
EV board.
Action
Function
Set P1 to “ON” position.
Connect the EN pin of the AAT2870 to be high level
to enable the AAT2870.
Set P2 to “100%” position or connect P2 to
external signal source when using external
PWM signal to control the AAT2870.
Set P3 to "Down" and P4 to "UP".
Connect P5 of the AAT2870 Evaluation board
to the 5 x 2 header of the I2C USB board.
Connect the I2C USB board to the computer
by USB port.
Set PWM control.
Set ambient light sensor to be Low gain mode.
Connect the AAT2870 evaluation board, I2C USB
board and the computer.
Step3: Run Windows GUI.
Run the AAT2870 Windows GUI.
The Windows GUI will show “Connection” when the
computer connects to USB interface board succesfully.
Step4: Apply power to the
board.
Step5: Adjust the windows
GUI to control the AAT2870.
External power is applied to VIN and GND
terminals of the AAT2870 Evaluation board.
Set 2.7V ~ 5.5V voltage to power the AAT2870.
Refer to the “Windows GUI” section.
Set appropriate Registers data to achieve expected
functions.
Table 1: Steps of Hardware Configuration.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 5: AAT2870 Evaluation Board Connection Demonstration.
Windows GUI
The AAT2870 uses an I2C serial interface to set backlight LED current, LDO output voltage, ALS configuration, Fade in/
out, Registers data as well as other housekeeping functions.
Run the AAT2870 Windows GUI program on the computer. Before configure the Windows GUI program, we must make
sure that the I2C USB interface board is connected to the computer and ready for communication. Figure 6 and Figure
7 show the connection status and how to set up the connection between the computer and I2C USB board.
Note:
1. We could click the “Reset AAT2870” button to reset the AAT2870’s registers data to default value. Because register
11h is used to read only, so it can’t be reset by this button.
2. The AAT2870 register address is 0x60h, please check the bottom left corner of the program to ensure the device
address is 60h.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
5
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 6: Connected Status between I2C USB Board and Computer.
Figure 7: Unconnected Status between I2C USB Board and Computer.
6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
This Windows GUI program has 7 sheets as follows:
•
•
•
•
•
•
•
“Backlight”, for LED current configuration and Fade in/out control;
“ALS Setup”, for ALS configuration;
“LDO”, for LDO enable and voltage configuration;
“Registers”, for registers operation;
“Script”, for saving and loading ‘User File’;
“Examples”, for illustration;
“Log”, for recording operated code and register addresses.
“Backlight” Sheet:
This sheet is for basic function operation for LED backlight, including two blocks: “Backlight Control” and “Fade In/Out
Control”. Figure 8 shows the “Backlight” sheet.
Figure 8: Backlight Sheet.
Backlight Control
•
•
•
•
"Enable": Every channel can be enabled/disabled individually.
"Group": Set channel to be main group, sub group or independent.
"Current": Select LED Current from 0.45mA to 27.9mA with 32 current levels.
"Write Selected Backlight Registers": Only selected channel data will be sent to the AAT2870 when clicking the button.
Fade In/Out Control
•
•
•
•
•
"Enable Main/Sub Group Fade In/Out": Enable/disable fade in / fade out function for the main/sub LED group.
"Group": Select main channels or sub channels for fade in/out.
"Fade Time": Four values 1s, 0.8s, 0.6s and 0.4s can be selected.
"Fade Floor Level": The lower 16 of the 32 LED backlight current levels can be chose to be the fade floor level.
"Fade In" and "Fade Out": Send the setting data by clicking the buttons.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
7
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Note:
1. When a channel is set to Main or Sub group, the channel current can only change through “Main group current” or
“Sub group current” bottons. Each channel current can only be changed when the channel is set as “independent”.
2. Don’t forget to click the button “Write Selected Backlight Registers” to send the setting data to registers, or the
registers data won’t change and your setup won’t work.
“ALS Setup” Sheet:
The sheet is used to control the ambient light sensor of the evaluation board. The ambient light sensor is used to measure the brightness of the surrounding environment. Based on the brightness level, the AAT2870 can adjust the backlight LED current according to ALS × registers setting value, leading to longer battery life and comfortable viewing with
less eyestrain.
The AAT2870 allows user to choose an inexpensive ambient-light sensor while offering a ±10% part-to-part variation
by providing an automatically calibrating gain adjustment from -50% to +43.75% for any off-the-shelf ambient-light
sensor.
The Windows GUI provide a setup process to help user to do appropriate ALS setup. We will introduce the parameters
of the four blocks and the parameters setup process. Figure 9 shows the ALS setup sheet.
Figure 9: ALS Setup Sheet.
All ALS configuration are involved into this sheet. It includes 4 blocks: “Ambient Light Sensor Settings”, “ALS LED
Current Dimming Level”, “Sub Group” and “Miscellaneous”.
Ambient Light Sensor Settings
• VALS(MAX):
Without Gain Adjustment, the VALS(MAX) should be 1.6V, but if we choose Gain adjustment, the VALS(MAX) should be calculated as below:
8
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
VALS(MAX) =
1.6
1 + Gain_ADJ
The following “Output Gain Adjustment” item describes the step of selecting suitable Gain_ADJ.
• Max Brightness and Floor Brightness: Set the range of ambient light brightness.
• Max LED Current and Floor LED Current: Set the range of LED current.
• ALS Output (μA/10Lux):
The item reflects the relationship between ambient light brightness and ALS output current. The evaluationg board
uses BH1600FVC as the ALS which has two gain modes. The gain mode of BH1600FVC can be chose by setting the
GC1 and GC2 level. Table 2 shows the detailed setup. We could change P3 and P4 of the evaluation board connections to set the GC1 and GC2 level. In High gain mode, the ALS output gain is 6μA/10Lux, and in Low gain mode, it
is 0.63μA/10Lux. So, if low gain is set in the evaluation board, 0.63 is filled in this item of the Windows GUI.
GC1
GC2
0
0
1
1
0
1
0
1
Mode
Shut down
High Gain Mode
Low Gain Mode
Test Mode(Input prohibition)
Table 2. ALS Mode Setting.
• ALS Sensor Type
It has 2 options: “Linear” and “Logrithmic”, depending on the characteristics of the ambient light sensor. For
BH1600FVC, we set it to be “Linear”.
• Digital ALS Output
This item can be set to be linear or logarithmic manner. Each manner divides LED brightness into 16 levels with linear or logarithmic style.
• ALC Backlight Profile
This item can be set to be “Linear/Logarithmic”. Each manner divides LED current into 16 levels with linear or logarithmic style.
Note: The sets for “ALS Sensor Type”, “Digital ALS Output” and “ALC Backlight Profile” are related. They could be set
as 3 modes as Table 3. In Windows GUI, we have configured this relation.so be relaxed.
Mode
Mode1
Mode2
Mode3
ALS Sensor Type
Digital ALS Output
ALC Backlight Profile
Linear/Logarithm
Linear
Logarithm
Linear
Linear
Linear
Linear
Logarithm
Logarithm
Table 3. ALS Level Setting Mode.
• Gain Resistor
There are 4 pairs of resistors including 250Ω/1kΩ, 1kΩ/4kΩ, 4kΩ/16kΩ, and 16kΩ/64kΩ. When the ALS Output is
voltage, the gain resistor is not needed. If the ALS Output is current, we must select a suitable resistor to transer it
to voltage to achieve better precision. If the expected ALS Output high voltage exceeds the SBIAS, an external voltage source is needed to power the ALS. At this time, the “External ALS BIAS Supplied” item should be selected. If
the resistor pairs provided by the AAT2870 are not suitable, an external resistor should be connected and the Input
Gain Mode should select “Fixed Gain Mode”.
• Output Offset Adjustment
Any leakage current will cause an offset at the output of the ambient light sensor, leading to inaccurate measurement
of the light brightness. The AAT2870 provide an Offset Adjustment function to correct the offset.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
9
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
The step of Offset Adjustment configuration lists as below,
1. Configure board and make correct board connections as the “Board Configuration and Connection” section.
2. Run Windows GUI, then begin to do suitable setup.
3. Determine the light brightness range. We set the max light brightness as 10000Lux in daylight.
4. Determine the sensor type of ALS. ALS BH1600FVC’s sensor type is linear.
5. Choose the Gain resistor. Usually choose 4kΩ in Low Gain Mode.
6. Enable the SBIAS and ALS.
7. Set the SBIAS voltage to be the max value 3V.
8. Don’t forget to enable the Test Mode.
9. Click “Read Ambient Level. 11h” button to read the AMB (11h) register for the ambient-light sensor output offset.
10.The ambient light level is indicated by 5 bits, the offset level is indicated by 4 bits. When we know the 11h register data, we could adjust the offset by changing OS_ADJ[3:0] as table 4.
AMB: Ambient Light Sensor
Digital Output Read Data Register
ALS_CFG1: Ambient Light Sensor
Voltage Bias and Offset Calibration Register
ALS 5-Bit Offset Measurement in Test Mode
ALS 4-Bit Offset Measurement in Test Mode
AMB[4]
AMB[3]
AMB[2]
AMB[1]
AMB[0]
OS_ADJ[3]
OS_ADJ[2]
OS_ADJ[2]
OS_ADJ[2]
Offset
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
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
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
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
too
too
too
too
too
too
too
too
too
too
too
too
too
too
too
too
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
+1
+2
+3
+4
+5
+6
+7
0
1
0
1
0
1
0
1
-8
-7
-6
-5
-4
-3
-2
-1
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
Offset
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
high
high
high
high
high
high
high
high
high
high
high
high
high
high
high
high
Table 4. Ambient Light Sensor 5 Bit to 4 Bit Offset Conversion.
10
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
• Output Gain Adjustment
For the majority of ambient-light sensors, the part-to-part variation of the output current is guaranteed to be ±20%
at best. Because the part-to-part difference of the input gain, we need output gain adjustment to achieve a constant
input gain. The step of output gain adjustment configuration lists as below:
1. Because we need to get the result of output gain from the ALS output voltage, we must do the output offset
adjustment firstly.
2. Set the SBIAS voltage. Because we don’t know the detailed gain adjustment, we set the voltage to be the max
value 3V at the start. If the gain adjustment is enough big, we probably need higher external voltage than 3V.
3. Enable the SBIAS and ALS.
4. Test the ALS real output voltage called Adjusted Full-Scale. Thus we could calculate the gain adjustment as
below:
Gain_ADJ =
Ideal Full Scale - Adjusted Full Scale
Adjusted Full Scale
Ideal Full Scale = 1.6V
5. Compare the test value of Gain_ADJ to the scheduled Gain value shown as Table 5. Then we could choose corresponding value to configure the registers.
Gain_ADJ[3:0]
Gain Adjustment
(%)
Full-Scale
(V)
REG 10h
0111
0110
0101
0100
0011
0010
0001
0000
1111
1110
1101
1100
1011
1010
1001
1000
43.75
37.50
31.25
25.00
18.75
12.50
6.25
0
-6.25
-12.50
-18.75
-25.00
-31.25
-37.50
-43.75
-50.00
1.11
1.16
1.22
1.28
1.35
1.42
1.51
1.60
1.71
1.83
1.97
2.13
2.33
2.56
2.84
3.20
07h
06h
05h
04h
03h
02h
01h
00h
0Fh
0Eh
0Dh
0Ch
0Bh
0Ah
09h
08h
AMB_IN Voltage Range
Low(V)
High(V)
1.04
1.09
1.14
1.20
1.26
1.33
1.41
1.50
1.60
1.71
1.85
2.00
2.18
2.40
2.67
3.00
1.18
1.24
1.30
1.36
1.43
1.51
1.60
1.70
1.81
1.94
2.09
2.27
2.47
2.72
3.02
3.40
Table 5. Ambient Light Sensor Gain Adjustment.
• SBIAS Output
The SBIAS can be set to be 3V, 2.8V, 2.7V, and 2.6V. Because SBIAS comes from VIN through a LDO, so the SBIAS
voltage can’t be set higher than VIN. In the evaluation board, the SBIAS powers the ambient light sensor.
• Input Gain Mode
There are four options for input gain mode, including Auto Gain Mode, Fix Gain Mode, High Gain Mode, and Low Gain
Mode. When we choose Auto Gain Mode, the gain mode will vary between High Gain Mode and Low Gain Mode auotmatically depending on the ambient light brightness. When we need to use an external gain resistors, the Fix Gain
Mode should be selected.
• Polling Mode
When we enable the ALS function, the ambient light sensor begins to sense the ambient light brightness discontinuously. We call this mode Polling Mode. In this mode, the work time becomes shorter, the power loss decreases. Figure
20 and Figure 21 show the waveform of polling mode.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
11
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
• Polling Time
There are four options for Polling Time, including 0.5s, 1s, 1.5s and 2s. The polling time is the period of polling mode.
When AMB_IN ≥ 0.4V, the polling-on time is 200mS in every period; when AMB_IN ≤ 0.4V, the polling-on time is
300mS in every period.
ALS LED Current Dimming Level
After Setting and adjusting ALS parameters, the middle block "ALS LED Current Dimming Level" lists ALS LED current
dimming registers (ALS0~ALSF), and the corresponding brightness, LED current and data(Hex).
If don’t click the button of “Change Dimming Level Data Automatically”, the user can manually change the registers
value in the column of “Data”. But the calculation is so complicated to achieve logarithmic response or linear response,
we don’t advise configuring manually. Table 6 shows the calculation formulas.
The other way round, if click “Change Dimming Level Data Automatically”, the registers value will vary with the change
of “Max Brightness”, “Floor Brightness”, “Max LED Current”, “Floor LED Current”, “Digital ALS Output” and “ALC Backlight
Profile” in the left block automatically.
The “Digital ALS Output” is used to divide the Brightness. When we set this item to be “Linear”, the brightness is
divided into 16 levels averagely from floor brightness to max brightness. And if it is set to be “Logarithmic”, the brightness is dvided into 16 leves as logarithmic manner.The calculation equations list in Table 6.
The “ALC Backlight Profile” is used to divide the LED Current. If it is set as “Linear”, the LED current is also divided into
16 levels averagely from max LED current to floor LED current. And If it is set as “Logarithmic”, the LED current is
dvided into 16 levels as logarithmic manner. The calculation equations list in Table 6.
Number
Equation 1
Equation 2
Equation 3
Equation 4
Equation
Comment
lg
BrightnessMAX
BrightnessFLOOR
Brightness(NREG) = BrightnessFLOOR ∙ 10
Brightness(NREG) = BrightnessFLOOR +
15
IALC = IFLOOR ∙ 10
IMAX
IFLOOR
15
IMAX - IFLOOR
15
∙ NREG
∙ NREG
Brightness grouping calculation
with Logarithmic manner.
∙ NREG
BrightnessMAX - BrightnessFLOOR
lg
IALC = IFLOOR +
15
∙ NREG
Brightness grouping calculation
with Linear manner.
LED current grouping calculation
with Logarithmic manner.
LED current grouping calculation
with Linear manner.
Table 6. LED Brightness and Current Calculation Equations.
Sub Group
• Response to ALS Read Data Enable
All sub group channels can be programmed to respond to the brightness of the surrounding environment independent
of the Main group.
• Response High Threshold: can be set to all 16 ALSx level.
• Response Low Threshold: can be set to all 16 ALSx level.
• Response Mode: include “Dimming” mode and “Brightening” mode. Please consult the datasheet to know more details
about them.
Note: We must know that the Ceiling Level is 19.8mA as default, and it is different from the “response high threshold”
that we could set manually; and the Floor Level is 0.45mA as default, different from the “response low threshold”.
12
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Miscellaneous
• ALS Enable: Enable/Disnable the Ambient Light Sensor function.
• CABC PWM Input Enable: Enable/Disnable the CABC PWM input.
• ALS Output Offset Test Mode Enable: Enable the Test Mode. When adjusting the offset, we need to enable the test
mode.
• External ALS Bias Supplied: when we use an external power source to power the ALS, we should click this item.
Note:
1. Click “Read Ambient Level. 11h”, the data read from the external Amient Light Sensor register(11h) is shown at
the right of the button.
2. When selecting “Test Mode”, the AAT2870 will not adjust LED current automatically to respond surrounding light
brightness.
The setup flowchart of Ambient Light Sensor lists as below:
Figure 10: ALS Setup Flowchart.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
13
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
We can configure the registers manually as indicated in the flowchart above, but it’s complicated. In order to help users
to do the setup, Windows GUI provide a setup process in “ALS Setup” sheet, as shown in Figure 11. When you click
any step, the corresponding items in the left block will change in the font color. Then we could set these parameters
to get a suitable setup.
Figure 11: Ambient Light Sensor Setup Process.
By virtue of the performance of the BH1600FVC as ALS in the AAT2870 EV board, we could ignore the DC offset setup.
In daylight, we usually take the following steps:
1.
2.
3.
4.
Choose low gain mode, 0.63μA/10Lux.
Choose gain resistor pair to be 4kΩ/8kΩ.
Choose gain adjustment to be -37.5% corresponding AMB-IN full Scale voltage 2.56V.
Set SBIAS voltage to be 3V.
“LDO” Sheet
Figure 12 shows "LDO" sheet which lists four low dropout linear regulators (LDOs) in the AAT2870.
• Enable: Enable the four LDOs.
• Output Voltage: Set the LDO voltage between 1.2V and 3.3V.
• Write LDO Registers: Change the LDO registers data when clicking the button.
Note:
1. Don’t forget to click “Write LDO Register” button after setup.
2. The four low dropout linear regulators (LDOs) can be set individually.
3. LDOA is different from LDOB, LDOC, and LDOD. LDOB, LDOC and LDOD have the same characteristics.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 12: LDO Sheet.
“Registers” Sheet
This sheet list all 39 registers of the AAT2870. It is for those customers who have been already familiar with the
AAT2870 setting for registers. They can control the AAT2870 registers directly through this sheet. When some configurations are done in “Backlight” sheet, “ALS Setup” sheet and “LDO” sheet, the corresponding registers data in this sheet
will change at the same time.
The 39 registers are divided into 3 groups:
• 14 for Main/Sub backlight enable, and fade in/out function control and configuration.
• 22 for ambient light sensor control and configuration.
• 3 for LDOs control and configuration.
Please refer to the AAT2870 datasheet for details.
Figure 13 shows “Registers” sheet.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
15
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 13: Registers Sheet.
There are four buttons in the bottom of this sheet: “Write All Selected Registers”, “Update View”, “Dump Registers
Value” and “Read Ambient Level. 11H”.
•
•
•
•
Write All Selected Registers: Send the configurations to corresponding registers.
Update View: Update the registers data.
Dump Registers Value: Save current registers data.
Read Ambient Level. 11H: Read the data from external ambient light sensor register.
Note:
1. All configurations, including in “Backlight” sheet, “ALS Setup” sheet and “LDO” sheet, can be directly configured by
setting the registers in “Registers” sheet.
2. The buttons with highlighed characters means high level “1”, and the buttons with grey characters means low level
“0”. Clicking the buttons can change the level, and writing into the “Data” column can change registers data directly.
“Script” Sheet
The sheet has three buttons of “Load”, “Save” and “Dump” to manage registers data more conveniently.
• Load: Load registers addresses and data that have been saved before.
• Save: After loading some registers data, we can do some literalness explanation for each register. Clicking this button can save addresses and data of registers and the literalness explanation.
• Dump: Save the current setting of each registers in the “Registers” sheet (without the literalness explanation).
Figure 14 shows "Script" sheet.
16
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 14: Script Sheet.
“Examples” sheet
This sheet provides some register configuration examples for demonstrating functions of the AAT2870.
Figure 15 shows “Examples” sheet.
Figure 15: Examples Sheet.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
17
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
“Log” Sheet
This is a record sheet. When registers has any change, this page will record the operating time, write/read, register
addresses and register data. These data can be saved, cleared and selectively cleared. Figure 16 shows “Log” sheet.
Figure 16: Log sheet.
Test Waveform
Negative Charge Pump Waveform
Figure 17 shows the operating wave of negative charge pump under VIN =3.6V, ILED = 27.9mA, and PWM = 100%.
18
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 17: Operating Waveform of Negative Charge Pump.
(CH1:C2+, CH2:C2-, CH3: C1+, CH4:C1-)
CH
CH1(C2+)
CH2(C2-)
CH3(C1+)
CH4(C1-)
Max Voltage
Min Voltage
1.8V
-0.12V
0.16V
-1.76V
3.48V
-0.04V
1.8V
-1.72V
PWM Dimming Waveform
Figure 18 shows the operating waveform of the PWM dimming under VIN = 3.6V, ILED = max value 27.9mA, with external PWM signal of 50% duty cycle and 10kHz frequency.
Note: With the different D (duty cycle) of PWM signal, the VCF (CF , namely C11) will achieve different voltage, and LED
will achieve corresponding D for internal 82 KHz frequency PWM. Please consult Figure 29 and Figure 30 in the AAT2870
datasheet to know detailed information about the relationship between PWM signal, VCF and LED switch frequency.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
19
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 18. Operating Waveform of PWM Dimming.
(CH1:PWM, CH2:VCF, CH3:VBL1, CH4:ILED(CH1))
Main/Sub Group Waveform
Figure 19 shows the voltage waveform of NEG, BL1 and BL2 under VIN = 3.6V, ILED - CH1 = 3.6mA, and ILED - CH2 =
27.9mA. CH1 is the main channel, and CH2 is the sub channel.
Note: Larger LED current with larger VF (LED forward voltage) leads to smaller VBLx. The main channel and sub channel
can be set individually.
20
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Fiture 19. Operating Voltage Waveform of NEG, BL5, BL8.
(CH1:VBL1, CH2:VBL2, CH3:ILED(CH1), CH4:ILED(CH2))
CH
CH1(VBL1)
CH2(VBL2)
CH3(ILED(CH1))
CH4(ILED(CH2))
Max Value
Min Value
0.896V
0.776V
0.416V
0.264V
6.6mA
4mA
33.8mA
24.2mA
Polling Mode Waveform
Figure 20 and Figure 21 show the waveform of the polling mode under VIN = 3.6V, SBIAS = 2.6V and polling time =
0.5s.
Note: In order to achieve polling time function, we must configure “Input Gain Mode” as ‘Auto Gain Mode’ in Windows
GUI. When AMB_IN voltage is smaller than 0.4V, the polling time should be 300ms; when bigger than 0.4V, the polling
time should be 200ms.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
21
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Figure 20: Operating Waveform of Polling Mode at AMB_IN>0.4V.
(CH1:SBIAS, CH2:AMB_IN, CH4:ISBIAS)
Figure 21: Operating Waveform of Polling Mode at AMB_IN<0.4V.
(CH1:SBIAS, CH2:AMB_IN, CH4:ISBIAS)
22
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
LDO Start-up Waveform
Figure 22 shows the waveform of LDO start-up under VIN = 3.6V, while LDOA and LDOB (set to be 1.2V as default) are
enabled synchronously.
Figure 22: Operating Waveform of LDO Start-up
(CH1:SCL, CH2:LDOA, CH3:LDOB, CH4:IIN)
Printed Circuit Board
(a) Top Side.
(b) Bottom Side.
Figure 23: AAT2870 Evaluation Board.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012
23
EVALUATION BOARD DATA SHEET
EV194
Evaluation Board for the AAT2870 CABC Compatible, Ambient Light Control,
Charge pump LED Backlight Driver & Four LDOs
Component Listing
Component
Part Number
Description
U1
U2
C1, C3, C4, C5
C8 - C10
C2
C6, C7
C11
R1-R8, R11
R9
P1, P2, P3, P4
P5
D1-D8
AAT2870IUW-T1
BH1600FVC
Backlight and LDO Lighting Management Unit
Ambient Light Sensor
GRM188R60J225KE01B
2.2μF, 6.3V, 10%, X5R; 0603
GRM188R60J475ME19B
GRM188R71A224KA01D
GRM033R71A103KA01D
Chip Resistor
Chip Resistor
NRPN361PAEN
4.7μF, 6.3V, 10%, X5R; 0603
0.22μF, 10V, 10%, X7R; 0603
10nF, 10V, 10%, X7R; 0402
0Ω, 1%, 1/4W; 0603
100Ω, 1%, 1/4W; 0603
2mm Header, 3 pins
0.1" Header, 2 × 5 pins
White LED Diode
LW M673
Manufacturer
Skyworks
Rohm
Murata
Vishay
Sullins Electronics
OSRAM
Table 7: AAT2870 Evaluation Board Bill of Materials.
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
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
responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale.
THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES
NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
use or sale.
Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
24
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202326A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012