Analog Devices ADD8702 Datasheet

12-Channel Gamma Buffers

FEATURES
Programmable 12-Channel Gamma Reference Generator
Mask Programmable Adjustable V
Upper/Lower Outputs Swing to V

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/GND

DD

Buffer

Continuous Output Current: 10 mA
V

Peak Output Current: 250 mA

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Outputs with Fast Settling Time for Load Change
Output Pins Are Compatible with ADD8701
Single-Supply Operation: 7 V to 16 V
Supply Current: 15 mA Max

APPLICATIONS
TFT LCD Panels

GENERAL DESCRIPTION

The ADD8702 is a low cost, mask programmable, 12-channel
gamma reference generator, plus an adjustable V

driver. This

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part is designed to provide gamma correction for high resolution
TFT LCD panels. The 12 gamma reference levels and V

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are
mask programmable to 0.3% resolution using the on-chip 500
chain resistor string. This reduces component and board costs.

The ADD8702 provides a complete programmed set of gamma
voltage references for the LCD source drivers. These references
settle quickly to load change. The V

output is stable with

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high capacitive loads and can source or sink 250 mA peak cur­rent. The V

output level can be adjusted using an external

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trim-potentiometer or discrete resistors.

with V

Buffer

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ADD8702

FUNCTIONAL BLOCK DIAGRAM

OUT

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V

GND

VGMA12

VGMA11

VGMA10

VGMA9

VGMA8

LOW

V

DD

V

VGMA7

GND

24

23

22

21

20

19

18

17

GND

V

DD

VGMA6

VGMA5

VGMA4

VGMA3

VGMA2

VGMA1

32 31 30 26 28 27 26 25

V

1

DD

V

ADJ

V

HIGH

VIN11

V

IN

V

V

V

2

3

4

10

5

6

9

IN

7

8

IN

7

8

IN

9 10 11 12 13 14 15 16

6

5

4

3

IN

IN

V

V

2

IN

IN

IN

V

V

V

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The output pins are compatible with the ADD8701. This allows
for single board design and fast turns for prototyping using the
initial ADD8701 board design.

The ADD8702 is specified over the temperature range of –40°C
to +85°C and comes in the 32-lead lead frame chip scale pack­age (LFCSP) for compact board space.

PAN E L
TIMING

CONTROLLER

TIMING AND CONTROL

SCAN DRIVER CONTROL

SCAN

DRIVERS

768

SOURCE DRIVER

NO. 1

384

R

G B

Figure 1. Typical SVGA TFT LCD Application

REV. 0

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. 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 companies.

ADD8702

SOURCE DRIVER

NO. 2

384

TFT COLOR PANEL

1024  768

GAMMA

REFERENCE

VOLTAG ES

SOURCE DRIVER

NO. 8

384

GAMMA

V

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One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

ADD8702–SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

(VDD = 16 V, TA = 25ⴗC, unless otherwise specified.)

Parameter Symbol Conditions Min Typ Max Unit

OUTPUT ACCURACY

V

ERROR V

SYSTEM

SY ERROR

10 50 mV

MASK PROGRAMMABLE
RESISTOR STRING

Total Resistor String R
Resistor Matching R

TOTAL

MATCH

500 Elements V

LOW

to V

HIGH

22.5 kΩ

Any Two Segments 1 %

OUTPUT CHARACTERISTICS

Output Voltage High V

OUT

(VGMA11, VGMA12) I

Output Voltage Mid V

OUT

IL = 100 µA 15.995 V

= 5 mA 15.85 15.95 V

L

–40°C ≤ T

≤ +85°C 15.75 V

A

IL = 5 mA 14.6 V
(VGMA3 to VGMA10)
Output Voltage Low V

OUT

IL = 100 µA5mV
(VGMA1, VGMA2) IL = 5 mA 50 150 mV

Continuous Output Current I
Peak Output Current I
Settling Time—Voltage t

CHARACTERISTICS

V

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Continuous Output Current I
Peak Output Current I
Settling Time—Voltage t

OUT

PK

S

OUT

PK

S

–40°C ≤ T

1 V Step 0.1%, RL = 10 kΩ, CL = 200 pF 1 µs

1 V Step 0.1%, RL = 10 kΩ, CL = 200 pF 0.8 µs

≤ +85°C 250 mV

A

10 mA
150 mA

35 mA
250 mA

SUPPLY CHARACTERISTICS

Supply Voltage V

DD

716V

Power Supply Rejection Ratio PSRR VS = 6 V to 17 V, –40°C ≤ TA ≤ +85°C6875 dB

SUPPLY CURRENT I

SYS

No Load 11 15 mA

–40°C ≤ TA ≤ +85°C16mA

Specifications subject to change without notice.

REV. 0–2–

ADD8702

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage (VS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V

Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C

Operating Temperature Range . . . . . . . . . . . .–40°C to +85°C

Junction Temperature Range . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature Range (Soldering, 60 sec.) . . . . . . . . 300°C

ESD Tolerance (HBM) . . . . . . . . . . . . . . . . . . . . . . . ± 1,000 V

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent 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.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

ADD8702ACP-R2 –40°C to +85°C 32-Lead LFCSP CP-32
ADD8702ACP-REEL –40°C to +85°C 32-Lead LFCSP CP-32
ADD8702ACP-REEL7 –40°C to +85°C 32-Lead LFCSP CP-32

PIN CONFIGURATION

OUT

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32 V

31 GND

30 VGMA12

29 VGMA11

Package Type 

1

JA



2

JB

Unit

32-Lead LFCSP (CP) 35 13 °C/W

NOTES

1

θJA is specified for worst-case conditions, i.e., θ

in circuit board for surface-mount packages.

2

ψJB is applied for calculating the junction temperature by reference to the board

temperature.

28 VGMA10

27 VGMA9

26 VGMA8

25 VGMA7

is specified for device soldered

JA

V

1

DD

ADJ 2

V

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V

HIGH

VIN11 4
V

10 5

IN

9 6

V

IN

V

8 7

IN

7 8

V

IN

PIN 1
INDICATOR

3

ADD8702

TOP VIEW

6 9

5 10

4 11

3 12

2 13

IN

IN

IN

IN

V

IN

V

V

V

V

14

LOW

V

15

V

DD

24 GND
23 V
22 VGMA6
21 VGMA5
20 VGMA4
19 VGMA3
18 VGMA2
17 VGMA1

GND 16

DD

PIN FUNCTION DESCRIPTIONS

Pin No. Mnemonic Description

1, 15, 23 V

2V

3V
4–13 V
14 V

DD

ADJ V

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HIGH

11–VIN2Gamma Buffer Inputs

IN

LOW

Power (+)

Adjust Input

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Highest Gamma Input Voltage

Lowest Gamma Input Voltage

16, 24, 31 GND Power (–)

17–22, 25–30 VGMA1–VGMA12 Gamma Buffer Outputs

32 V

OUT V

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Buffer Output

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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 the
ADD8702 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.

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