Analog Devices ADD8707 a Datasheet

12-Channel Gamma Buffers

FEATURES

12 precision gamma reference outputs Mask-programmable gamma resistors:

0.2% resolution and 0.1% accuracy Mask programmable voltage regulator: 0.4% accuracy Upper 6 buffers swing to V Lower 6 buffers swing to GND Single-supply operation: 7.5 V to 16 V Gamma current drive: 15 mA per channel

peak output current: 250 mA

V

COM

Outputs stable under load conditions 48-lead, Pb-free LFCSP package

APPLICATIONS

LCD TV panels LCD monitor panels

PRODUCT OVERVIEW

The ADD8707 is a 12-channel integrated gamma reference with VCOM for use in LCD TV and monitor panels. The output buffers feature high current drive and low offset voltage to provide an accurate and stable gamma curve. The top six channels swing to VDD and the lower six channels swing to GND.

Integrating the gamma setup resistors drastically reduces the external component count while increasing the gamma curve accuracy. To accommodate multiple column drivers and panel architectures, the ADD8707 is mask-programmable to a 0.2% resolution using the on-chip 500 resistor string. An on-board voltage regulator provides a fixed input for the resistor string, isolating the gamma curve from supply ripple.

The ADD8707 is specified over the temperature range of –40°C to +105°C and comes in a 48-lead, Pb-free, lead frame chip-scale package.

DD

with V

FUNCTIONAL BLOCK DIAGRAM

MASK-PROGRAMMABLE REGULATOR RESISTORS

GND

V

11

IN

V

10

IN

V

8

IN

V

7

IN

V

6

IN

V

5

IN

V

3

IN

V

2

IN

1

V

IN

700Ω*

*ESD PROTECTION RESISTORS

and Regulator

COM

FB

700Ω*

+

1.2V –

PROGRAMMABLE

GAMMA RESISTORS

MASK-

Figure 1. 48-Lead LFCSP

ADD8707

COM IN–

V

GAMMA BUFFERS

COM IN+

V

COM

V

COM OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

12

11

10

9

8

7

6

5

4

3

2

1

04712-001

REG OUT

V

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.

www.analog.com

ADD8707

TABLE OF CONTENTS

Electrical Characteristics ................................................................. 3

Absolute Maximum Ratings............................................................ 5

Pin Configuration and Function Description .............................. 6

Typical Performance Characteristics ............................................. 8

Application Notes ........................................................................... 12

Tap Point Selection ..................................................................... 12

Volt a ge R e gu l ator ....................................................................... 13

Maximum Power Dissipation ...................................................13

Land Pattern................................................................................ 13

Operating Temperature Range ................................................. 14

Typical Applications Ci r c u it ..........................................................16

Development Circuit...................................................................... 17

Tap Point and Regulator Voltage Request Form......................... 19

Regulator Section—V

...................................................... 19

REG OUT

Tap Point S ec t ion ........................................................................ 19

Outline Dimensions ....................................................................... 20

Ordering Guide........................................................................... 20

REVISION HISTORY

10/04—Data Sheet Changed from Rev. 0 to Rev. A

Changes to Product Overview Section .......................................... 1

Changes to Figure 1.......................................................................... 1

Changes to Electrical Characteristics Section .............................. 3

Changes to Absolute Maximum Ratings Section......................... 5

Changes to Pin Configuration and Function Description.......... 6

Changes to Typical Performance Characteristics Section........... 8

Changes to Applications Notes Section....................................... 12

Changes to Figure 28, Typical Applications Circuit................... 16

Added Development Circuit Section........................................... 17

Added Tap Point and Regulator Voltage Request Form............ 19

Changes to Ordering Guide.......................................................... 20

7/04—Revision 0: Initial Version

Rev. A | Page 2 of 20

ADD8707

ELECTRICAL CHARACTERISTICS

VDD = 16 V, TA @ +25oC, unless otherwise noted.

Table 1.

Parameter Symbol Condition Min Typ Max Unit

GAMMA CURVE CHARACTERISTICS

Accuracy R Programming Resolution R Total Resistor String Value R

BUFFER CHARACTERISTICS

OUTPUTS

Output Voltage Range (Ch12 to Ch7) V Output Voltage Range (Ch6 to Ch1) V

Output vs. Load (Ch12, Ch11, Ch2, Ch1) Output vs. Load (Ch10 to Ch3)

INPUTS

Offset Voltage V Offset Voltage Drift

Input Bias Current I

Input Voltage Range (Ch12 to Ch7) V Input Voltage Range (Ch6 to Ch1) V

V

CHARACTERISTICS

COM

Offset Voltage V Input Range V

Peak Output Current I Continuous Output Current I Output vs. Load

BUFFER AND V

DYNAMIC PERFORMANCE

COM

Slew Rate SR RL = 10 kΩ, CL = 200 pF 4 6 V/µs Bandwidth BW −3dB, RL = 10 kΩ, CL = 200 pF 4.5 MHz Settling Time to 0.1%

Phase Margin Power Supply Rejection Ratio PSRR

VOLTAGE REGULATOR

Programmable Range V

Initial Regulator Accuracy V Dropout Voltage V

I Line Regulation REG Load Regulation REG

Maximum Load Current I

Feedback Reference Voltage V Feedback Input Bias Current I

ACC

RES

TOTAL

OUT

∆V ∆V

OS

∆V

B

IN

OS

IN

PK

OUT

∆V

t

S

φ

o

REG OUT

ACC

DO

O

REF

B FB

OUT

OS

COM

1

/∆T

LINE

LOAD

0.1 0.4 % 500 segments 0.2 % 15 kΩ

IL = 100 µA IL = 100 µA

2

IL = 20 mA 15 mV

2

IL = 5 mA 5 mV

1.4 V 0

V

DD

− 1.4

V V

5 15 mV

−40°C ≤ T

≤ +105°C

A

−40°C ≤ TA ≤ +105°C

1.4 V 0

20

0.5 1.5

DD

V

− 1.4

DD

µV/°C

µA

V V

5 15 mV

1.4

V

DD

− 1.4

V

250 mA 50 mA

2

IL = 30 mA 10 mV

1V step, RL = 10 kΩ, CL = 200 pF 1.1 µs RL = 10 kΩ, CL = 200 pF 55 Degrees

V

= 7 V to 17 V, −40°C ≤ TA ≤ +105°C

DD

5

No Load. V

= 14.4V 0.4 1.5 %

REG OUT

IL = 100 µA

= 5 mA 310 350 mV

L

VIN = 8.5 V to 16.5 V, V

= 8V 0.01 0.20 %/V

OUT

IO = 100 µA to 5 mA

−40°C ≤ TA ≤ +105°C

68 90 dB

V

DD

− 0.6

V

100 150 mV

0.02 0.10 %/mA 5 mA

1.2 V

−40°C ≤ TA ≤ +105°C −150

10 150 nA

Rev. A | Page 3 of 20

ADD8707

Parameter Symbol Condition Min Typ Max Unit

SYSTEM ACCURACY 10

Total Error3, POWER SUPPLY

Supply Voltage V

Supply Current I

1

Gamma curve accuracy includes resistor matching and buffer errors, but excludes the regulator error.

2

∆V

is the shift from the desired output voltage under the specified current load.

COM

3

Total error is defined as the difference between the designed and actual output voltage divided by the actual regulator output voltage or full-scale voltage.

4

Total error includes regulator error, resistor string error, bias current effects, and buffer offset voltage.

4

V

TOTAL ERROR

DD

SY

–40°C ≤ TA ≤ +105°C 0.5 3 %

7.5 16 V No load, –40°C ≤ TA ≤ +105°C 8.3 15 mA

Rev. A | Page 4 of 20

ADD8707

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Supply Voltage (VDD) 18 V Input Voltage

Storage Temperature Range Operating Temperature Range

1

−0.5 V to V

DD

−65°C to +150°C

−40°C to +105°C

Lead Temperature Range (Soldering 10 sec) 300°C Junction Temperature 150°C ESD Tolerance (HBM) ±3000 V ESD Tolerance (MM) ±100 V

Table 3. Thermal Resistance

Package Type

2

θ

JA

3

θ

JA

Unit

48-Lead LFCSP (CP) 28.3 47.7 °C/W

1

See the Applications Information section.

2

θJA for exposed pad soldered to JEDEC 4-layer board.

3

θJA for exposed pad not soldered down.

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 section 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.

Rev. A | Page 5 of 20

ADD8707

PIN CONFIGURATION AND FUNCTION DESCRIPTION

12

11

10

9

8

7

OUT

DD

GND

V

2

1

–

IN

V

COM IN

V

REG OUT

GND

V V

V

ADD8707

TOP VIEW

(Not to Scale)

5

IN

NC

V

3

IN

V

NC

V

48 47 46 45 44 43 42 41 40 39 38 37

1

NC

2

V

3

DD

4

5

FB NC

6

NC

7

8

11

IN

9

10

IN

10

NC

V

11

8

IN

12

NC

13 14 15 16 17 18 19 20 21 22 23 24

7

6

IN

NC

V

Figure 2. 48-Lead LFCSP

6

OUT

V

+

COM IN

V

5

V

NC

OUT

NC

36

35

34

33

32

31

30

29

28

27

26

25

NC NC NC V

OUT

V

OUT

V

OUT

V

OUT

V

DD

GND V

COM OUT

NC NC

4 3 2 1

04712-0-002

Table 4. Pin Function Descriptions

Pin No. Name Description

1 NC 2 GND Ground. Normally 0 V. 3 V 4 V

DD

REG OUT

Supply voltage. Normally 16 V. Regulator output voltage. Provides reference voltage to resistor string and is internally connected to the top of

the resistor string.

5 FB

Regulator feedback pin. Compares a percentage of the regulator output to the internal 1.2V voltage reference.

Internal resistors are used to program the desired regulator output voltage. 6 NC 7 NC 8 VIN11 9 VIN10

Buffer inputs. Normally floating.

1

10 NC 11 VIN8 Buffer inputs. Normally floating.1 12 NC 13 NC 14 VIN7 15 VIN6

Buffer inputs. Normally floating.

1

16 VIN5 17 NC 18 VIN3 19 VIN2

Buffer inputs. Normally floating.

1

20 VIN1 21 V 22 V

COM IN

- V + V

amplifier inverting input.

COM

amplifier non-inverting input.

COM

23 NC 24 NC

1

External resistors can be added to modify the internal resistor string to change the gamma voltage. An external resistor calculator is available upon request.

Rev. A | Page 6 of 20