Texas Instruments BUF08821EVM User manual

User's GuideSBOU066 – September 2008
BUF08821EVM Evaluation Board and Software Tutorial
This user's guide describes the characteristics, operation, and use of the BUF08821EVM evaluationboard. It discusses how to set up and configure the software and hardware, and reviews various aspectsof the program operation. Throughout this document, the terms evaluation board,evaluation module, andEVM are synonymous with the BUF08821EVM. This user's guide also includes information regardingoperating procedures and input/output connections, an electrical schematic, PCB layout drawings, and aparts list for the EVM.
Contents1 Overview ...................................................................................................................... 22 Unpacking the EVM ......................................................................................................... 23 BUF08821EVM Software ................................................................................................... 24 EVM Operation ............................................................................................................... 55 Using the BUF08821EVM Software ....................................................................................... 86 Hardware and Schematic ................................................................................................. 18
List of Figures
1 BUF08821EVM Software Installation ..................................................................................... 32 COM Port Selection and Dialog Window ................................................................................. 33 BUF08821EVM Software About Button ................................................................................... 44 BUF08821EVM Switch and Jumper Locations .......................................................................... 55 BKSEL Switch ................................................................................................................ 66 BUF08821EVM Jumper JP1 Set for Logic '1' ............................................................................ 67 BUF08821EVM Jumper JP1 Set for Logic '0' ............................................................................ 68 BUF08821EVM Jumper JP2 Set for BKSEL Switching ................................................................. 79 BUF08821EVM Jumper JP2 Set for External Signal Switching ....................................................... 710 BUF08821EVM Software GUI ............................................................................................. 811 Power Supply Measurement and Recording ............................................................................. 912 Reset and Read DAC Buttons ............................................................................................ 1013 Save to File Dialog Box ................................................................................................... 1114 Working with a Saved BUF08821 Data File ............................................................................ 1215 Load From File Button ..................................................................................................... 1316 Changing the DAC Analog Voltage ...................................................................................... 1417 Run Batch Dialog Box ..................................................................................................... 1518 Control Panel Button and Graphical Sliders ............................................................................ 1619 Program OTP All Channels Button ...................................................................................... 1720 Program OTP Out Button and Write OTP Reg Dialog ................................................................ 1721 Max Bank Field ............................................................................................................ 1822 BUF08821EVM Schematic ................................................................................................ 1923 BUF08821EVM PCB Top Layer (Component Side) ................................................................... 2024 BUF08821EVM PCB Bottom Layer (Solder Side) ..................................................................... 21
Pentium is a registered trademark of Intel Corporation.Microsoft, Windows are registered trademarks of Microsoft Corporation.I
2
C is a trademark of NXP Semiconductors, Inc.All other trademarks are the property of their respective owners.
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1 Overview
2 Unpacking the EVM
3 BUF08821EVM Software
3.1 Hardware Requirements
Overview www.ti.com
The BUF08821 is a programmable gamma-voltage generator and V
COM
calibrator with integrated two-bankmemory. This device offers 8 programmable gamma channels and one programmable V
COM
channel. TheBUF08821EVM is a platform for evaluating the performance of the BUF08821 under various signal,reference, and supply conditions.
This document gives a general overview of the BUF08821EVM, and provides a general description of thefeatures and functions to be considered while using this evaluation module.
Upon opening the BUF08821EVM kit, please check to make sure that the following items are included:•One BUF08821EVM printed circuit board (PCB);•One serial connection cable with RS-232/RJ-45 plug connector; (RS-232 and RJ-45 connectors)•One CD containing the BUF08821EVM software, and electronic copies of the BUF08821 product datasheet and this user's guide ;
If any of these items are missing, please contact the Texas Instruments Product Information Centernearest you to inquire about a replacement.
The minimum hardware requirements for the BUF08821EVM sofware are:•IBM PC-compatible computer with a Microsoft
®
Windows
®
98/ME/NT/2000/XP operating system•Pentium
®
or equivalent processor•64MB of RAM•Hard disk drive with at least 100MB free space•Available COM port•Mouse
•VGA adapter card and monitor
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3.2 Installation
3.3 Software Description and Set-Up
www.ti.com BUF08821EVM Software
The BUF08821EVM software is included on the CD that is shipped with the EVM. It is also availablethrough the BUF08821EVM product folder on the TI web site at www.ti.com . To download the software toyour system, insert the disc into an an available CD-ROM drive. Navigate to the drive contents and openthe BUF08821EVM software folder. Locate the compressed file ( BUF08821EVM.zip) and open it. Extractthe BUF08821EVM files into a specific BUF08821 folder on your hard drive.
Once the files are unzipped, navigate to the BUF08821 folder that you created on your hard drive. Locatethe setup.exe file; click the file to start the installation process, as shown in Figure 1 .
Figure 1. BUF08821EVM Software Installation
Follow all on-screen commands to finish installing the software.
The EVM software is controlled through a graphical user interface (GUI). The software communicates withthe EVM through an available COM or other serial port on the PC. Pressing the COM Setting buttonbrings up a panel that allows you to change the serial port number through which the PC communicateswith the BUF08821EVM, as shown in Figure 2 . COM1 is an appropriate choice for most PCs. You canalso set the appropriate baud rate through the same dialog box.
Figure 2. COM Port Selection and Dialog Window
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BUF08821EVM Software www.ti.com
The BUF08821EVM software allows the user to read and write to all registers in the BUF08821 gammacorrection buffer. Furthermore, it allows programming of the OTP register on the BUF08821. The softwarealso permits the user to select either I
2
C™ address.
Press the About button as shown in Figure 3 to verify that you have the latest version of the software.
Figure 3. BUF08821EVM Software About Button
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4 EVM Operation
www.ti.com EVM Operation
Figure 4 shows the BUF08821EVM with the test point, switch, and jumper locations noted.
Figure 4. BUF08821EVM Switch and Jumper Locations
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4.1 BKSEL
Bank 1
Bank 2
BKSEL
4.2 JP1
Set for Logic ‘1’ Software set for A0 = 1
Set for Logic ‘0’ Software set for A0 = 0
EVM Operation www.ti.com
The BKSEL switch (illustrated in Figure 5 ) selects the memory bank to be used when operating the EVM.Bank 1 selects the gamma curve that is stored in Bank_0 of the BUF08821. Bank 2 selects the gammacurve that is stored in Bank_1 of the BUF08821.
The SCL and SDA jumpers must be installed on the EVM in order to allow communication between theboard and the BUF08821. The communications cable must be connected to COM1 or another COM porton your PC.
Figure 5. BKSEL Switch
Jumper JP1 is used to set the I
2
C address pin of the BUF08821 to logic high or logic low. When J1 is inthe position shown in Figure 6 , A0 on the BUF08821 is connected to DV
DD
(logic '1'). Note that thesoftware Change Address button must be as shown in Figure 6 for A0 = '1'.
Figure 6. BUF08821EVM Jumper JP1 Set for Logic '1'
When JP1 is in the position shown in Figure 7 , A0 on the BUF08821 is connected to GND (logic '0'). Notethat the software must be as shown in Figure 7 for an address of A0 = '0'.
Figure 7. BUF08821EVM Jumper JP1 Set for Logic '0'
Note: Pressing the Change Address button (located near the top of the interface) changes the I
2
Caddress that the software writes to. In Figure 7 , the address is A0 = '0'. Pressing the buttonchanges it to A0 = '1', as shown in Figure 6 . Note that the Change Address button iscolor-coded to help you quickly identify the current address. Red indicates that the address isA0 = '0'.
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4.3 JP2
JP2 selects either BKSEL
or an external signal
In this position, BKSEL
is used to switch
between memory banks
Int
Ext
JP2
BKSEL
JP2 selects either BKSEL
or an external signal
In this position, memory banks
switched according to
external signal
applied via connector
Int
Ext
JP2
BKSEL
www.ti.com EVM Operation
Jumper JP2 selects either the BKSEL switch on the EVM or an external signal to switch between the twononvolatile memory banks of the BUF08821. When JP2 is in the position shown in Figure 8 , the BKSELswitch is used to switch between the memory banks.
Figure 8. BUF08821EVM Jumper JP2 Set for BKSEL Switching
When JP2 is in the position shown in Figure 9 , the memory banks are switched according to the externalsignal applied via the connector.
Figure 9. BUF08821EVM Jumper JP2 Set for External Signal Switching
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5 Using the BUF08821EVM Software
Using the BUF08821EVM Software www.ti.com
Figure 10 shows the EVM software interface.
Figure 10. BUF08821EVM Software GUI
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5.1 Change Address Button
5.2 Measuring the Power Supply
Measure the power-supply value
(V ) against GND, and
enter it here
S
The voltage out of each DAC
will be calculated according to
the V value entered.
S
Changing this cell immediately changes
the output of DAC8 to 0.996V.
www.ti.com Using the BUF08821EVM Software
The interface displays the last power-supply value used for the new address. This feature is helpful whenchanging back to an address that was previously used. Whenever the address is changed, a Read DACcommand is automatically performed so that all the DAC output displays are updated. Red indicates thatthe address is A0 = '0', as Figure 10 shows.
You must measure the power supply (V
S
) value against GND, and then enter it in the Vsup field of thesoftware interface, as shown in Figure 11 . The voltage out of each DAC is calculated according to the V
Svalue entered.
Figure 11. Power Supply Measurement and Recording
Measure V
S
at the location indicated in Figure 4 .
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V = V Code_in_decimal´
DAC_CHANNEL S
1024
(1)
V = 15V 68 / 1024 = 0.996V´
DAC_CHANNEL
5.3 Reset and Read DAC Buttons
5.4 Save to File
Using the BUF08821EVM Software www.ti.com
For example, changing the value in the DAC 15 cell immediately changes the output of DAC15 to 0.996V.The calculation is performed according to Equation 1 .
For example:
DAC 15: Code 44 (hexadecimal) = 68 (decimal)
Push the ReadDAC button to read the binary value in the DAC output registers of the BUF08821. Pushingthe Reset button forces an I
2
C general call reset and causes all registers in the BUF08821 to reset to therespective default values (mid-code or V
S
/2). Figure 12 illustrates the Reset and Read DAC buttons.
Figure 12. Reset and Read DAC Buttons
The register configurations of the BUF08821 DACs are displayed in both analog voltage and inhexadecimal (see Figure 11 ). The DAC codes (that is, gamma voltages) can be saved into a text file usingthe Save to File button.
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www.ti.com Using the BUF08821EVM Software
Pressing the Save to File button opens a file-save dialog box similar to that shown in Figure 13 . Pressingthe folder icon creates a new folder on your PC. It is a good idea to create a directory exclusively forBUF08821 DAC code (gamma voltage) files. Enter a unique file name in the File name field to store yourBUF08821 register information. Press the Open button to save the file.
Figure 13. Save to File Dialog Box
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Using the BUF08821EVM Software www.ti.com
Saving the BUF08821 DAC codes (gamma voltages) creates a text file that can be opened in aspreadsheet program or text editor, as illustrated in Figure 14 .
Figure 14. Working with a Saved BUF08821 Data File
The first entry in the file is the power-supply value. Fields 2 through 17 contain the DAC codes (decimal)for Outputs 1 through 16. Fields 20 and 21 contain the DAC codes (decimal) for V
COM
1 and V
COM
2.
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5.5 Loading a Saved Data File
www.ti.com Using the BUF08821EVM Software
The BUF08821EVM software is also able to load data saved from previous evaluations. A saved registerconfiguration can be loaded into the BUF08821 using the Load From File button, shown in Figure 15 . Theprogram remembers where you saved the last register configuration. Simply select the desiredconfiguration and press Open.
Figure 15. Load From File Button
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5.6 Changing the DAC Analog Voltage
The analog voltage of any DAC
can be directly edited.
The hexadecimal value associated with the DAC
updates according to changes in the analog voltage,
but it cannot be edited.
Up arrow increases DAC
count by one
Down arrow decreases DAC
count by one
Using the BUF08821EVM Software www.ti.com
The analog voltage of any DAC can be directly edited, as Figure 16 shows.
Figure 16. Changing the DAC Analog Voltage
Note, however, that the hexadecimal value associated with the DAC updates according to changes in theanalog voltage, but it cannot be directly edited.
If you select a DAC and click on the up arrow control, the DAC register increases by one count.Conversely, clicking on the down arrow control decreases the DAC register by one count.
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5.7 Run Batch Button
www.ti.com Using the BUF08821EVM Software
The Run Batch button (as noted in Figure 17 ) enables the user to configure the BUF08821 to cyclethrough different register configurations in a continuous loop. When connected to the end application, thisfeature can be used to cycle through different gamma settings to determine what the optimal settings mustbe for a given application.
When the Run Batch button is pressed, a new dialog box displays, as shown in Figure 17 . The delay timeis the amount of time in between loading new configurations into the BUF08821.
Figure 17. Run Batch Dialog Box
Use the Single Step Up and Single Step Down buttons to step through the selected files manually. Thecurrently-selected file name is displayed in the lower left corner area of the dialog box. Press the < Shift>key and click on the files you want to select. In Figure 17 , two configuration files are selected.
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5.8 Control Panel
Using the BUF08821EVM Software www.ti.com
Pressing the Control Panel button brings up a display panel that allows you to adjust each channel using aset of graphical sliders, as shown in Figure 18 . Simply drag the slider to adjust the desired channel output.The DAC output value changes automatically.
Figure 18. Control Panel Button and Graphical Sliders
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5.9 Program OTP All Channels Button
5.10 Program OTP Out Button
www.ti.com Using the BUF08821EVM Software
As Figure 19 shows, pressing the Program OTP All Channels button allows you to program a gammacurve into the nonvolatile memory in the BUF08821. All eight channels (and the V
COM
channel) are thenprogrammed simultaneously. The values are stored in the memory bank that is selected via the BKSELswitch (see Section 4.1 ).
Figure 19. Program OTP All Channels Button
Pressing the Program OTP Out button (illustrated in Figure 20 ) allows you to store the value of a specificchannel into the nonvolatile memory in the BUF08821. This feature is useful when the V
COM
channelsmust be programmed at different times. The values are stored in the memory bank that is selected via theBKSEL switch. The Write OTP Reg dialog box appears.
Figure 20. Program OTP Out Button and Write OTP Reg Dialog
In the example shown in Figure 20 , to program 0.996V into the nonvolatile memory of channel 8, use theup and down arrows to select channel 8. Then press the Write Selected Reg to OTP button.
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5.11 Max Bank Field
Max Bank Field
6 Hardware and Schematic
Hardware and Schematic www.ti.com
The Max Bank field at the top of the software interface (see Figure 21 ) shows how many times thememory of the most-programmed channel of the selected memory bank has been previously written.•None: Max Bank shows 0.•Once: Max Bank shows 0.•Twice: Max Bank shows 1.•Three times: Max Bank shows 2.•16 times: Max Bank shows 15.
Figure 21. Max Bank Field
This section contains the complete bill of materials, schematic diagram, and PCB layouts for theBUF08821EVM.
Note: Board layouts are not to scale. These are intended to show how the board is laid out; theyare not intended to be used for manufacturing BUF08821EVM PCBs.
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6.1 Schematic
TP VS
VSD 2.0V
VSD 2.0V
VSD 2.0V
VSD 2.0V
VSD 2.0V
TP GND
VS
GND
JP7
J4
J2
Header 9
Parts Optional--Not Populated
VS
VS
VS1
1
1
10
10
1
1
1
13
1
1
1
1
2
2
2
2
2
2
5
5
4
5
2
2
2
2
2
2
3
3
3
5
3
3
3
3
3
4
4
4
3
H
L
JP1
JP2
JP5
JP6
U1
U3
U7
U6
U5
U4
A0
BKSEL
SDA
SDA TP_SDA
SCL
SCL TP_SCL
4
4
4
5
5
5
6
6
6
8
8
8
9
9
9
RB
F2
RC
F3
RD
F4
RE
F5
RF
RG
RH
RI RA
F1
R11
R2
R3
R1
R6
R21
R5 (Optional--Not Populated)
L1
L2
S1
RA to RI are all 0W
7
7
7
20
28
11
19
11
19
27
18
26
18
17
25
17
16
24
16
15
23
15
13
21
13
12
20
12
14
22
14
BUF08821
C16
0.1 Fm
C18
0.1 Fm
C7
0.1 Fm
C8
0.1 Fm
C1
0.1 Fm
C19
0.1 Fm
R19
10kW
R20
10kW
C13
0.1 Fm
C14
0.1 Fm
C12
0.1 Fm
C5
22 Fm
J1
1
2
3
1kW
4.7kW
4.7kW
10kW
249kW
6.81kW
VSD
VSD
VSD
VSD
VS
VS
VSD
C6
C11
C2
C10
C9
C4
C3
+
+
+
+
+
+
+
1.5 Fm
10 Fm
10 Fm
10 Fm
10 Fm
1.5 Fm
1.5 Fm
U2
TPS79901-DDC
UA78M33 REGULATOR
T
exas
Instruments
MAX3238
8
7
6
5
4
3
1
2
VIN
Adj
EN
GND
VOUT
VIN
VOUT/
Tab
COM VSD
1
2
3.9 Hm
www.ti.com Hardware and Schematic
Figure 22 shows the schematic for the BUF08821EVM.
Figure 22. BUF08821EVM Schematic
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6.2 PCB Layouts
Hardware and Schematic www.ti.com
Figure 23 and Figure 24 show the PCB layout of the BUF08821EVM.
Figure 23. BUF08821EVM PCB Top Layer (Component Side)
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