18 precision gamma reference outputs
Mask-programmable voltage regulator: 0.4% accuracy
Upper 9 buffers swing to VDD
Lower 9 buffers swing to GND
Single-supply operation: 7.5 V to 16.5 V
Gamma current drive: 15 mA per channel
Peak output current: 150 mA
Output voltage stable under load conditions
48-lead, Pb-free LQFP package
APPLICATIONS
LCD TV panels
LCD monitor panels
GENERAL DESCRIPTION
The ADD8709 is an 18-channel integrated gamma reference for
use in LCD TV and monitors panels. The output buffers feature
high current drive and low offset voltage to provide an accurate
and stable gamma curve. The top nine channels swing to V
and the lower nine channels swing to GND.
An on-board voltage regulator provides a fixed input for the
gamma buffers, isolating the gamma curve from supply ripple.
The ADD8709 is specified over the temperature range of
–40°C to +105°C and comes in a 48-lead, Pb-free, low-profile
quad flat package.
DD
V
REG OUT
with Regulator
FUNCTIONAL BLOCK DIAGRAM
V
GND
DD
700Ω*
FB
V
18
IN
17
V
IN
16
V
IN
15
V
IN
V
14
IN
V
13
IN
V
12
IN
V
11
IN
V
10
IN
V
9
IN
V
8
IN
V
7
IN
V
6
IN
V
5
IN
V
4
IN
V
3
IN
V
2
IN
V
1
IN
VOLTAGE
REGULATOR
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
ADD8709
VDDV
DD
GAMMA
BUFFERS
V
18
OUT
V
17
OUT
V
16
OUT
V
15
OUT
V
14
OUT
V
13
OUT
V
12
OUT
V
11
OUT
V
10
OUT
V
9
OUT
V
8
OUT
V
7
OUT
V
6
OUT
V
5
OUT
V
4
OUT
V
3
OUT
V
2
OUT
V
1
OUT
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
7.5 16.5 V
No load, −40°C ≤ TA ≤ +105°C 10.5 17 mA
Rev. A | Page 3 of 16
ADD8709
www.BDTIC.com/ADI
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Supply Voltage (VDD) 18 V
Input Voltage –0.5 V to V
Storage Temperature Range –65°C to +150°C
Operating Temperature Range
Junction Temperature Range –65°C to +150°C
Lead Temperature Range (Soldering, 60 sec) 300°C
ESD Tolerance (HBM) ±2000 V
ESD Tolerance (MM) ±150 V
Table 3. Package Characteristics
Package Type θ
LQFP (ST) 74.57 °C/W
1
See section. Application Notes
1
JA
−40°C to +105°C
Unit
DD
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods
may affect device reliability.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Buffer inputs. An external resistor calculator is available upon request from your local sales office.
15 VIN8
16 VIN7
17 VIN6
18 VIN5
19 VIN4
20 VIN3
21 VIN2
22 VIN1
23 GND Ground. Normally 0 V.
24 V
25 V
26 V
DD
OUT
OUT
1
2
Supply voltage. Normally 16 V.
Buffer outputs. These buffers can swing to ground.
VDDGND
9
10
IN
IN
V
V
8
V
OUT
IN
OUT
OUT
V
V
ADD8709
TOP VIEW
(Not to Scale)
7
6
IN
IN
V
V
V
5
V
OUT
IN
V
4
V
OUT
IN
13
V
3
V
OUT
IN
12
11
DD
OUT
OUT
GND
V
V
2
IN
V
V
36
V
10
OUT
9
35
V
OUT
8
34
V
OUT
7
33
V
OUT
32
V
DD
GND
31
6
V
30
OUT
5
V
29
OUT
4
V
28
OUT
3
V
27
OUT
2
V
26
OUT
1
V
25
OUT
1
DD
IN
V
V
GND
04715-002
Rev. A | Page 5 of 16
ADD8709
www.BDTIC.com/ADI
Pin No. Name Description
27 V
28 V
29 V
30 V
31 GND Ground. Normally 0 V.
32 V
33 V
34 V
35 V
36 V
37 V
38 V
39 GND Ground. Normally 0 V.
40 V
41 V
42 V
43 V
44 V
45 V
46 V
47 GND Ground. Normally 0 V.
48 V
OUT
OUT
OUT
OUT
DD
OUT
OUT
OUT
OUT
OUT
OUT
DD
OUT
OUT
OUT
OUT
OUT
OUT
DD
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Buffer outputs. These buffers can swing to ground.
Supply voltage. Normally 16 V.
Buffer outputs. These buffers can swing to ground.
Buffer outputs. These buffers can swing to V
Supply Voltage. Normally 16V.
Buffer outputs. These buffers can swing to V
Supply voltage. Normally 16 V.
.
DD
.
DD
Rev. A | Page 6 of 16
ADD8709
www.BDTIC.com/ADI
TYPICAL PERFORMANCE CHARACTERISTICS
20
15
10
5
0
–5
–10
–15
–20
–25
OUTPUT VOLTAGE ERROR (mV)
–30
–35
–20–100 102030405060708090100110120
I
SOURCE
I
SINK
= 25mA
I
= 25mA
SINK
= 15mA
I
SOURCE
TEMPERATURE (°C)
= 15mA
I
LOAD
= 0mA
I
SOURCE
I
SINK
= 5mA
= 5mA
Figure 3. Output Voltage Error vs. Temperature
30
25
CH17 SOURCE
20
15
10
OUTPUT VOLTAGE ERROR (mV)
5
0
0.1110100
CH18 SOURCE
CH18 SINK
CH17 SINK
LOAD CURRENT (mA)
Figure 4. Output Voltage Error vs. Load Current (Channels 17 and 18)
30
25
20
15
10
OUTPUT VOLTAGE ERROR (mV)
5
0
0.1110100
CH10 SOURCE
CH16 SOURCE
LOAD CURRENT (mA)
CH10 SINK
CH16 SINK
Figure 5. Output Voltage Error vs. Load Current (Channels 10 and 16)
04715-003
04715-004
04715-005
25
20
CH3 SOURCE
15
10
5
OUTPUT VOLTAGE ERROR (mV)
0
0.1110100
LOAD CURRENT (mA)
CH3 SINK
CH9 SOURCE
CH9 SINK
Figure 6. Output Voltage Error vs. Load Current (Channels 3 and 9)
25
20
CH1 SOURCE
15
10
5
OUTPUT VOLTAGE ERROR (mV)
0
0.1110100
LOAD CURRENT (mA)
CH1 SINK
CH2 SOURCE
CH2 SINK
Figure 7. Output Voltage Error vs. Load Current (Channels 1 and 2)
1000
900
800
700
600
500
400
300
NUMBER OF AMPLIFIERS
200
100
0
–0.30 –0.18 –0.10 –0.020.060.140.220.30
GAMMA OUTPUT ERROR DUE TO OFFSET (% OF FS)
Figure 8. Gamma Output Voltage Error
04715-006
04715-007
04715-009
Rev. A | Page 7 of 16
ADD8709
www.BDTIC.com/ADI
11
10
9
8
7
6
5
4
AMPLITUDE (V)
3
2
1
0
–200180016001400120010008006004002000
TIME (ns)
Figure 9. Gamma Buffers Load Transient Response vs. Capacitive Loading
The ADD8709 is a gamma reference generator that allows
source drivers to be optimized for the different combinations
of liquid crystals, glass sizes, etc. in large LCD panels.
In a typical panel application, the selected source drivers have
an internal gamma curve that is not ideal for the specific panel,
as shown in Figure 19. The ADD8709 allows the gamma curve
in the source drivers to be adjusted appropriately, and also
ensures that all of the source drivers have the same gamma
curve.
16
14
12
10
8
6
PANEL GAMMA CURVE
CORRECTED BY ADD8709
GAMMA VOLTAGE (V)
4
2
0
Figure 19. Original and Corrected Gamma Cur ves
The ADD8709 also includes a low dropout linear regulator to
provide a stable reference level for the gamma curve for best
panel performance.
VOLTAGE REGULATOR
The on-board voltage regulator provides a regulated voltage to
the external resistors to set different gamma voltages.
The output of the regulator is set by the two resistors, R
and an internal reference voltage of 1.2V. In the ADD8709, R
are external components. The output voltage can is
and R
2
found by
= V
V
REG OUT
× (R2/R1 + 1)
REF
5kΩ
V
1.2V
ORIGINAL GAMMA CURVE
IN SOURCE DRIVERS
GAMMA REFERENCE INPUT POINTS
R
2
R
REF
Figure 20. Voltage Regulator
55kΩ
1
V
REG OUT
+
–
04715-021
04715-020
and R2,
1
1
MAXIMUM POWER DISSIPATION
The maximum safe power dissipation in the ADD8709 package
is limited by the associated rise in junction temperature (T
) on
J
the die. At approximately 150°C, the glass transition temperature, the properties of the plastic change. Even temporarily
exceeding this temperature limit may change the stresses that
the package exerts on the die, permanently shifting the parametric performance of the ADD8709. Exceeding a junction
temperature of 175°C for an extended period can result in
changes in the silicon devices, potentially causing failure.
OPERATING TEMPERATURE RANGE
The junction temperature is
= T
T
where:
T
AMB
= junction-to-ambient thermal resistance, in °C/watt.
θ
JA
P
DIS
For the ADD8709, P
where:
V
DD
I
OUT X(+)
dissipation (current comes from V
−I
OU XT(-)
dissipation (current goes to GND).
(V
DD
Example 1
To calculate an estimated power consumption of the ADD8709
assume:
+ θJA × P
J
AMB
DIS
= ambient temperature.
= power dissipated in the device, in watts.
can be calculated by
DIS
= VDD × IDQ + Σ(I
P
DIS
Σ(−I
× I
DQ
× V
OUT X(-)
= nominal system power requirements.
× (VDD − V
× V
OUT X
– V
V
DD
(V
) × I
REG OUT
× IDQ = 16 V × 15 mA = 0.240 W.
– V
DD
REG OUT
) + (VDD – V
OUTX
) = positive-current amplifier load power
OUT X
= negative-current amplifier load power
= regulator load power dissipation.
LOAD
) × I
LOAD
× (VDD − V
OUT X(+)
REG OUT
DD
OUT X
) × I
).
= (16 V – 14.4 V) × 5 mA = 0.008 W.
)) +
LOAD
Rev. A | Page 10 of 16
ADD8709
www.BDTIC.com/ADI
= 0.240 W + 0.731 W + 0.008 W =0.979 W
Table 5.
V
V
18 14.400 4.3 0.00688
OUT
V
17 11.405 5.2 0.0239
OUT
V
16 10.627
OUT
V
15 10.397 7.3 0.0409
OUT
V
14 10.195 7.6 0.0441
OUT
V
13 10.080
OUT
V
12 9.821 8.3 0.0513
OUT
V
11 9.130 7.9 0.0543
OUT
V
10 8.611
OUT
V
9 6.480
OUT
V
8 6.077 5.6 0.0556
OUT
V
7 5.098 -3.3 0.0168
OUT
V
6 4.810
OUT
V
5 4.694 5.7 0.0644
OUT
V
4 4.435 3.5 0.0405
OUT
V
3 4.205 9.6 0.113
OUT
V
2 3.398
OUT
V
1 0.202
OUT
Σ(I
OUT X(+)
(V) I
OUT X
× (VDD − V
OUT X
)) + Σ(−I
(mA) P (W)
OUT X
−4.4
−3.9
−4.5
−4.2
−6.9
−9.5
−7.2
× V
OUT X(-)
OUT X
)
0.0468
0.0393
0.0389
0.0272
0.0332
0.0323
0.00145
0.731
P
DIS
= 74.57°C/W, T
θ
JA
= 45°C + (74.57°C/W) × (0.979 W) = 118.0°C
T
J
AMB
= 45°C
Here, 150°C is the maximum junction temperature that is
ranteed before the part breaks down, while 125°C is the
gua
maximum process limit. Because T
is < 150°C and < 125°C,
J
this example demonstrates a condition where the part should
perform within process limits.