BUF12800
SBOS315 − DECEMBER 2004
REFERENCE VOLTAGE GENERATOR
for LCD GAMMA CORRECTION
FEATURES
D
D
D
D
D
D
D
D
D
D
D
12-CHANNEL GAMMA CORRECTION
10-BIT RESOLUTION
DOUBLE-BUFFERED DAC REGISTERS
INTEGRATED REFERENCE BUFFERS
RAIL-TO-RAIL OUTPUT
LOW SUPPLY CURRENT: 900µA/ch
SUPPLY VOLTAGE: 7V to 18V
DIGITAL SUPPLY: 2.7V to 5.5V
INDUSTRY-STANDARD TWO-WIRE INTERFACE
− High-Speed Mode: 3.4MHz
HIGH ESD RATING:
− 4kV HBM, 1kV CDM, 200V MM
DEMOBOARD AND SOFTWARE AVAILABLE
V
SD
4
V
S
1, 2
REFH
3
APPLICATIONS
D
TFT-LCD REFERENCE DRIVERS
D
REFERENCE VOLTAGE GENERATORS
D
INDUSTRIAL PROCESS CONTROL
DESCRIPTION
The BUF12800 is a programmable voltage reference
generator designed for dynamic gamma correction in
TFT-LCD panels. It provides 12 programmable outputs,
each with 10-bit resolution.
TI’s new, small geometry, state-of-the-art, analog CMOS
process allows the use of one digital-to-analog converter
(DAC) per channel while still maintaining a very small chip
size. This topology has the advantage of significantly
increased programming speed over existing program-
mable buffers.
Programming of each output occurs through an industry-
standard, two-wire serial interface. Unlike existing
programmable buffers, the BUF12800 offers a high-
speed, two-wire interface mode that allows clock speeds
up to 3.4MHz. The BUF12800 features a double-buffered
DAC register structure that significantly simplifies imple-
mentation of dynamic gamma control. This further reduces
programming time, especially when many channels have
to be updated simultaneously.
Reference pins set the high and low voltages of the output
range. They are internally buffered, which simplifies
design. They may be connected to external resistors to
divide the output range for finer resolution of outputs.
The BUF12800 is available in a TSSOP-24 PowerPAD
package. It is specified from −40°C to +85°C.
BUF12800
13
Out A
14
Out B
15
Out C
16
Out D
17
Out E
DAC Register
DAC Register
18
Out F
19
Out G
20
Out H
21
Out I
22
Out J
23
Out K
24
Out L
BUF12800 RELATED PRODUCTS
FEATURES
11-Channel Gamma Correction Buffer, Int VCOM
6-Channel Gamma Correction Buffer, Int VCOM
6-Channel Gamma Correction Buffer
4-Channel Gamma Correction Buffer, Int VCOM
High-Supply Voltage Gamma Buffers
20-Channel Programmable Buffer, 10-Bit, VCOM
PRODUCT
BUF11702
BUF07703
BUF06703
BUF05703
BUFxx704
BUF20800
6
SDA
Control IF
SCL
5
8
LD
A0
7
10
REFL
9
11, 12
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPAD is a registered trademark of Texas Instruments. All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright
2004, Texas Instruments Incorporated
www.ti.com
BUF12800
www.ti.com
SBOS315 − DECEMBER 2004
ABSOLUTE MAXIMUM RATINGS
(1)
Supply Voltage, VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +20V
Supply Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V
Signal Input Terminals, SCL, SDA, AO, LD:
Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.5V to +6V
Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±10mA
Output Short-Circuit(2) . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . −40°C to +95°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +125°C
Lead Temperature (soldering, 10s) . . . . . . . . . . . . . . . . . . . . +300°C
ESD Rating:
Human Body Model (HBM) . . . . . . . . . . . . . . . . . . . . . . . 4000V
Charged Device Model (CDM) . . . . . . . . . . . . . . . . . . . . 1000V
Machine Model (MM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200V
(1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods
may degrade device reliability. These are stress ratings only, and
functional operation of the device at these or any other conditions
beyond those specified is not supported.
(2) Short-circuit to ground, one amplifier per package.
This integrated circuit can be damaged by ESD. Texas
Instruments recommends that all integrated circuits be
handled with appropriate precautions. Failure to observe
proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to
complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could
cause the device not to meet its published specifications.
ORDERING INFORMATION
(1)
PRODUCT
PACKAGE-LEAD
PACKAGE
DESIGNATOR
PWP
SPECIFIED
TEMPERATURE
RANGE
−40°C to +85°C
PACKAGE
MARKING
BUF12800
ORDERING
NUMBER
BUF12800AIPWP
BUF12800
TSSOP-24
BUF12800AIPWPR
TRANSPORT
MEDIA, QUANTITY
Tube, 60
Tape and Reel, 2000
(1) For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet.
PIN CONFIGURATION
Top View
TSSOP
V
S
V
S
REFH
V
SD
SCL
SDA
A0
LD
GND
D(1)
REFL
GND
A(1)
GND
A(1)
1
2
3
4
5
6
7
8
9
10
11
12
PowerPAD
Lead−Frame
Die Pad
Exposed on
Underside
24
23
22
21
20
19
18
17
16
15
14
13
Out L
Out K
Out J
Out I
Out H
Out G
Out F
Out E
Out D
Out C
Out B
Out A
(1) GNDD and GNDA are internally connected and must be at the same voltage potential.
2
BUF12800
www.ti.com
SBOS315 − DECEMBER 2004
ELECTRICAL CHARACTERISTICS
Boldface
limits apply over the specified temperature range,
T
A
= −40°C to +85°C.
At TA = +25°C, VS = 18V, VSD = 5V, VREFH = 17V, VREFL = 1V, RL = 1.5kΩ connected to ground, and CL = 200pF, unless otherwise noted.
BUF12800
PARAMETER
ANALOG
Buffer Output Swing—High
Buffer Output Swing—Low
Buffer Output Reset and Power-Up Value
Buffer A
Buffer B
Buffer C
Buffer D
Buffer E
Buffer F
Buffer G
Buffer H
Buffer I
Buffer J
Buffer K
Buffer L
REFH Input Range
REFL Input Range
Integral Nonlinearity
Differential Nonlinearity
Gain Error
Program to Out Delay
Output Accuracy
vs Temperature
Input Resistance at VREFH and VREFL
Load Regulation, 10mA, All Buffers
50mA, Buffers A-F
ANALOG POWER SUPPLY
Operating Voltage Range
Total Analog Supply Current
over Temperature
DIGITAL
Logic 1 Input Voltage
Logic 0 Input Voltage
Logic 0 Output Voltage
Input Leakage
Clock Frequency
DIGITAL POWER SUPPLY
Operating Voltage Range
Digital Supply Current(1)
over Temperature
TEMPERATURE RANGE
Specified Range
Operating Range
Storage Range
Thermal Resistance, TSSOP-24(2)
Junction-to-Ambient
Junction-to-Case
CONDITIONS
Buffers A-F, Code = 1023, Sourcing 10mA, VREFH = 17.8
Buffers G-L, Code = 1023, Sourcing 10mA, VREFH = 17.8
Buffers A-F, Code = 0, Sinking 10mA, VREFL = 0.2
Buffers G-L, Code = 0, Sinking 10mA, VREFL = 0.2
Code 3E0h
Code 360h
Code 320h
Code 300h
Code 2C0h
Code 240h
Code 1C0h
Code 140h
Code 100h
Code 0E0h
Code 0A0h
Code 020h
(11 1110 0000)
(11 0110 0000)
(11 0010 0000)
(11 0000 0000)
(10 1100 0000)
(10 0100 0000)
(01 1100 0000)
(01 0100 0000)
(01 0000 0000)
(00 1110 0000)
(00 1010 0000)
(00 0010 0000)
MIN
17.7
16.3
TYP
17.8
16.98
1.0
0.2
16.502
14.500
13.500
13.002
12.002
10.000
8.005
6.008
5.007
4.509
3.507
1.507
MAX
UNIT
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Bits
Bits
%
µs
mV
µV/°C
MΩ
mV/mA
mV/mA
V
mA
mA
V
V
V
µA
kHz
MHz
V
µA
µA
°C
°C
°C
°C/W
°C/W
1.1
0.3
16.552
14.550
13.550
13.052
12.052
10.050
8.055
6.058
5.057
4.559
3.557
1.557
VS − 0.2
VS − 4
16.452
14.450
13.450
12.952
11.952
9.950
7.955
5.958
4.957
4.459
3.457
1.457
4
0.2
INL
DNL
tD
VREFH and VREFL Held Constant
RINH
REG
VOUT = VS/2, IOUT = +5mA to −5mA Step
VOUT = VS/2, ISINKING = 50mA, ISOURCING = 50mA
7
Outputs at Reset Values, No Load
0.3
0.3
0.12
5
±20
±25
100
0.5
0.5
±50
1.5
1.5
18
15
15
VS
IS
9
0.7(VSD)
ISINK = 3mA
fCLK
Standard/Fast Mode
High-Speed Mode
2.7
Outputs at Reset Values, No-Load, Two-Wire Bus Inactive
25
100
−40
−40
−65
30.13
0.92
0.15
±0.01
0.3(VSD)
0.4
±10
400
3.4
5.5
50
VSD
ISD
Junction Temperature < 125°C
+85
+95
+150
q
JA
q
JC
(1) See the typical characteristic
Digital Supply Current vs Two-Wire Bus Activity.
(2) PowerPAD attached to PCB, 0lfm airflow, and 76mm x 76mm copper area.
3
BUF12800
www.ti.com
SBOS315 − DECEMBER 2004
TYPICAL CHARACTERISTICS
At TA = +25°C, VS = 18V, VSD = 5V, VREFH = 17V, VREFL = 1V, RL = 1.5kΩ connected to ground, and CL = 200pF, unless otherwise noted.
ANALOG SUPPLY CURRENT vs TEMPERATURE
10
V
S
= 18V
8
V
S
= 10V
I
Q
(mA)
I
Q
(µA)
6
25
30
DIGITAL SUPPLY CURRENT vs TEMPERATURE
V
S
= 10V
V
SD
= 5V
20
15
V
SD
= 3.3V
10
4
2
5
0
−40
−20
0
20
40
60
80
100
−40
−20
0
20
40
60
80
100
Temperature (_ C)
Temperature (_ C)
0
Figure 1
FULL−SCALE OUTPUT SWING
18
REFH = 17V
REFL = 1V
Output Voltage (5V/div)
Output Voltage (V)
Code 3FF
→000
17
16
Figure 2
OUTPUT VOLTAGE vs OUTPUT CURRENT
Channel A (sourcing), Code = 3FFh
V
REFL
= 1V, V
REFH
= 17.8V
R
LOAD
Connected to GND
Channel L (sourcing), Code = 3FFh
V
REFL
= 0.2V, V
REFH
= 17V
R
LOAD
Connected to GND
Channel L (sinking), Code = 000h
V
REFL
= 0.2V, V
REFH
= 17V
R
LOAD
Connected to 18V
Code 000
→3FF
2
1
0
Channel A (sinking), Code = 000h
V
REFL
= 1V, V
REFH
= 17.8V
R
LOAD
Connected to 18V
Time (1µs/div)
0
10
20
30
40
50
60
70
80
90
100
Output Current (mA)
Figure 3
INTEGRAL NONLINEARITY ERROR vs INPUT CODE
0.6
0.4
0.2
0
−0.2
−
0.4
−
0.6
0
200
400
600
800
1000
Input Code
DNL Error (LSB)
INL Error (LSB)
0.6
0.4
0.2
0
−0.2
−
0.4
−
0.6
0
200
Figure 4
DIFFERENTIAL NONLINEARITY ERROR vs INPUT CODE
400
600
800
1000
Input Code
Figure 5
4
Figure 6
BUF12800
www.ti.com
SBOS315 − DECEMBER 2004
APPLICATIONS INFORMATION
The BUF12800 programmable voltage reference allows
fast and easy adjustment of 12 programmable reference
outputs, each with 10-bit resolution. It allows very simple,
time-efficient adjustment of the gamma reference
voltages. The BUF12800 is programmed through a
high-speed standard two-wire interface. The BUF12800
features a double-register structure for each DAC channel
to simplify the implementation of dynamic gamma control
(see the
Dynamic Control
section). This allows
pre-loading
of register data and rapid updating of all channels
simultaneously.
Buffers A−F are able to swing to within 300mV of the
positive supply rail, and to within 1.1V of the negative
supply rail. Buffers G−L are able to swing to within 1.7V
of the positive supply rail, and to within 300mV of the
negative supply rail. (See the
Electrical Characteristics
table for further information).
Each buffer is capable of full-scale change in output
voltage in less than 4µs; see Figure 4, typical
characteristic
Full-Scale Output Swing.
Figure 7 shows the BUF12800 in a typical configuration.
In this configuration, the BUF12800 device address is 74h.
The output of each DAC is immediately updated as soon
as data is received in the corresponding register (LD = 0).
For maximum dynamic range, set V
REFH
= V
S
− 0.2V and
V
REFL
= V
S
+ 0.2V.
BUF12800
1
V
S
2
V
S
(1)
V
S
(1)
Out L
24
Source
Driver
10µF
100nF
Out K
23
3
REFH
(1)
Out J
22
3.3V
1
µ
F
4
100nF
V
DS
(1)
Out I
21
5
Timing
Controller
6
SCL
(1)
Out H
20
(1)
SDA
Out G
19
7
A0
(1)
Out F
18
8
LD
(1)
Out E
17
9
GND
D(2)
(1)
Out D
16
V
S
10
REFL
(1)
Out C
15
11
GND
A(2)
(1)
Out B
14
12
GND
A(2)
(1)
Out A
13
(1) RC combination optional.
(2) GNDD and GNDA are internally connected and must be at the same voltage potential.
Figure 7. Typical Application Configuration
5
京公网安备 11010802033920号
EEWORLD
