BUF01900 Datasheet, PDF (8/25 Pages) Texas Instruments – Programmable Voltage Source with Memory

BUF01900
BUF01901
SBOS337A − OCTOBER 2006 − REVISED OCTOBER 2006
BUF01901: USING EXTERNAL V_COM BUFFER
Many LCD panel modules use gamma buffers, such as
TI’s BUFxx704, BUFxx703, BUF11702 and the new
BUF11705, that already include an integrated V_COM driver.
Some other LCD modules use more complicated com-
pensation schemes that require an external high-speed
V_COM op amp. BUF01901 is optimized for lowest cost and
is intended to be used with an external V_COM buffer or op
amp. Figure 16 illustrates a typical configuration of the
BUF01901 with the BUF11705.
ON-CHIP NONVOLATILE MEMORY
The BUF0190x is optimized for the smallest die size avail-
able and consequently the lowest cost to support high vol-
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ume production. The on-chip OTP (one-time-program-
mable) memory helps to achieve significant die size
reduction over EEPROM memory technology. This reduc-
tion is partly because of the smaller area of the OTP
memory cell, but also a result of the fact that an EEPROM
requires a high programming voltage typically generated
with an onboard charge pump. OTP memory technology
does not require the higher programming voltage; conse-
quently, no charge pump is needed, resulting in a smaller
and lower-cost solution.
During production, the V_COM voltage is typically adjusted
only once. However, to allow for programming errors and
rework, the BUF0190x supports a total of four write cycles
to the OTP memory. This capacity means that the pre-
viously programmed code in the OTP can be overwritten
a total of three times.
BUF11704
Digital
2V to 5.5V
Analog
7V to 18V
BUF01901
Voltage
Regulator
R₁
4 x OTP Switch
ROM
Control
10−Bit
DAC
250kΩ
BIAS
R₂
Input Control Logic
SDA SCL A0
Gamma
References
V_COM
Figure 16. BUF01901 Typical Configuration
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