FEATURES
D 18-CHANNEL GAMMA CORRECTION
D 2-CHANNEL PROGRAMMABLE V
COM:
100mA IOUT
D ON-CHIP OTP MEMORY
D 10-BIT RESOLUTION
D RAIL-TO-RAIL OUTPUT
D LOW SUPPLY CURRENT: 900A/ch
D SUPPLY VOLTAGE: 7V to 18V
D DIGITAL SUPPLY: 2.0V to 5.5V
D INDUSTRY-STANDARD, TWO-WIRE
INTERFACE: 3.4MHz HIGH-SPEED MODE
D HIGH ESD RATING:
4kV HBM, 1kV CDM, 200V MM
D DEMO BOARD AND SOFTWARE AVAILABLE
REFH OUT
7V18V
2V5.5V
REFL
AO
LD
SCL
SDA
OUT 1
OUT 18
REFL OUT
OUT 2
OUT 17
VCOM OUT1
VCOM OUT2
D
A
C
R
egi
s
ter
s
2
Control IF
…
18 Output Channels plus
Two VCOM Channels
BUF20820
D
A
C
R
egi
s
ter
s
1
…
OTP
Memory
Digital
Analog
REFH
P
rogr
am
C
o
m
and
APPLICATIONS
D REPLACES RESISTOR-BASED GAMMA
SOLUTIONS
D TFT-LCD REFERENCE DRIVERS
D DYNAMIC GAMMA CONTROL
DESCRIPTION
The BUF20820 is a programmable voltage reference
generator designed for gamma correction in TFT-LCD
panels. It provides 18 programmable outputs for gamma
correction and two channels for VCOM adjustment, each
with
10-bit resolution. It offers on-chip One-Time
Programmable (OTP) memory that allows the user to store
the gamma voltages on-chip. This eliminates the need for
an external EEPROM.
This programmability replaces the traditional, time-
consuming process of changing resistor values to optimize
the various gamma voltages and allows designers to
determine the correct gamma voltages for a panel very
quickly. Required voltage changes can also be easily
implemented without hardware changes.
The BUF20820 uses TI’s latest, small-geometry analog
CMOS process, which makes it a very competitive choice
for full production, not just evaluation.
Programming of each output occurs through an industry-
standard, two-wire serial interface. Unlike existing
programmable buffers, the BUF20820 offers a high-speed
mode that allows clock speeds up to 3.4MHz.
For lower or higher channel count, please contact your
local sales or marketing representative.
The
BUF20820
is
available
in
an
HTSSOP-38
PowerPAD
package. It is specified from 40°C to +85°C.
BUF20820 RELATED PRODUCTS
FEATURES
PRODUCT
18-Channel Programmable, Two VCOM
BUF20800
12-Channel Programmable Buffer, 10-Bit
BUF12800
Programmable VCOM with Memory
BUF01900
10-Channel Gamma Correction Buffer, Int VCOM,
18V Operating Supply Voltage
BUF11704
High-Speed VCOM, 1 and 2 Channels
SN10501
Complete LCD DC/DC Solution
TPS651xx
BUF20820
SBOS330E DECEMBER 2005 REVISED OCTOBER 2008
18-Channel GAMMA VOLTAGE GENERATOR
with Two Programmable VCOM Channels
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.
www.ti.com
Copyright
20052008, Texas Instruments Incorporated
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.