Alta Analog
ATT3209
Proprietary and Confidential
Page 7
Revision 2/7/2005
VGMA
RRATIO
VGMA0
0.909
VGMA1
0.660
VGMA2
0.525
VGMA3
0.393
VGMA4
0.319
VGMA5
0.264
VGMA6
0.180
VGMA7
0.024
VGMA8
0.000
Table1: RRATIO Table.
Dynamic Gamma Compensation
In many applications, especially those which
involve the display of video information such as
movies or television programming, it is desirable
to be able to change the gamma curve based on
the active frame information.
The ATT3209
stores thirty-two individual gamma curves that
can be dynamically ‘switched in’ by the panel’s
timing controller in response to the frame data.
Temperature and Gamma Profiles
The ATT3209 has two nonvolatile arrays. One
is the temperature profile. This array stores up
to
eight
programmable
voltage
references
against which the VTEMP input is compared.
As the VTEMP changes and transitions through
the preset temperature profile the low order
bank select (B0:B1 or B0:B2) will change,
effectively
selecting
a
new
gamma
profile
optimal for the current temperature.
These
signals used internally will also be output on the
B0:B2 pins.
The gamma profile array is comprised of thirty-
two (32) banks
of
nine
(9)
programmable
gamma outputs.
The active bank, or profile, is
selected by 5 of the 6 bank select inputs. The
active bank select inputs are determined by the
state of DTSEL as shown in Table 2.
ATT3209 Active and Inactive Bank Pins
DTSEL
B0
B1
B2
B3
B4
B5
VSS
A
A
A
A
A
IA
VCC
A
A
IA
A
A
A
Table 2. Active Bank Select pins.
When DTSEL is tied low, the ATT3209 is
configured with B0:B2 being used internally and
as active outputs reflecting the temperature
input, and B3 & B4 are used as the dynamic
gamma inputs.
When DTSEL is tied high, the ATT3209 is
configured with B0 & B1 being used internally
and as active outputs reflecting the temperature
input, and B3:B5 are used as the dynamic
gamma inputs.
ATT3209 and AGT3209
The ATT3209 is designed to work in conjunction
with the AGT3209.
When they are paired the,
the bank select pins are connected as shown in
table 3.
AGT3209 Pins
B0
B1
B2
B3
B4
VSS
B0
B1
B2
B3
B4
VCC
B0
B1
B3
B4
B5
Table 3. Shared pins.
VCOM
The ATT3209 also provides two “trimmable”
VCOM outputs. The nominal output is equivalent
to Panel AVDD/2. The VCOM output voltage can
be trimmed to AVDD/2 ±1V.
For example;
assume a LCD panel with a 14V panel AVDD,
then VCOM can be trimmed anywhere between
6V and 8V effectively in 8mV increments.
The ATT3209 is easily programmed either by
Alta Analog or the end user.
It can be
programmed as a standalone device in most any
test fixture or in-circuit on the assembled LCD-
panel.
PROGRAMMING
The programming interface is a set of three
inputs plus a digital supply (VCC).
SDA is the serial data input pin used to input
instructions to the ATT3209.
VPP is a dual function pin. It is first used to clock
in the serial data stream. Once the instruction
has been issued VPP will then be used as the
programming voltage input pin.
AOUT is a buffered analog voltage output that
reflects the VGMA voltage level of the cell
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