ANALOG DEVICES ADA4800 Service Manual

Low Power, High Speed

O

V

FEATURES

Integrated active load and gain of 1 buffer
Very low buffer power consumption

As low as 20 mW on chip

Power save feature to reduce active load current by GPO

control

High buffer speed

400 MHz, −3 dB bandwidth

415 V/μs slew rate
Fast settling time to 1%, 2 V step: 5 ns
Adjustable buffer bandwidth
Push-pull output stage
Adjustable active load current
Small package: 1.6 mm × 1.6 mm × 0.55 mm

APPLICATIONS

CCD image sensor output buffer
Digital still cameras
Camcorders

CCD Buffer Amplifier

ADA4800

FUNCTIONAL BLOCK DIAGRAM

VEE

ADA4800

1

IN

I

AL

2

3

UT

+1

Figure 1.

I

IDRV

I

BUFF

6

ISF

I

ISF

I

CC

5

VCC

4

IDRV

09162-001

GENERAL DESCRIPTION

The ADA4800 is voltage buffer integrated with an active load.
The buffer is a low power, high speed, low noise, high slew rate,
fast settling, fixed gain of 1 monolithic amplifier for charge­coupled device (CCD) applications. For CCD applications, the
active load current source (I
sensor outputs and the buffer can drive the AFE load. The active
current load can also be switched off, to use the ADA4800 as just
a unity gain buffer. The buffer consumes only 20 mW of static
power. In applications where power savings is critical, the
ADA4800 features a power save mode (see the Power Save
Mode section), which further reduces the total current
consumption. The bandwidth of the ADA4800 buffer is also
fully adjustable through the IDRV pin.

The buffer of the ADA4800 employs a push-pull output stage
architecture, providing drive current and maximum slew
capability for both rising and falling signal transitions. At a
5 mA quiescent current setting, it provides 400 MHz, −3 dB
bandwidth, which makes this buffer well suited for CCD
sensors from machine vision to digital still camera applications.

The ADA4800 is ideal for driving the input of the Analog
Devices, Inc., 12-bit and 14-bit high resolution analog
front ends (AFE) such as the AD9928, AD9990, AD9920A,

AD9923A, and AD997x family.

) can load the open source CCD

AL

The versatility of the ADA4800 allows for seamless interfacing
with many CCD sensors from various manufacturers.

The ADA4800 is designed to operate at supply voltages as low
as 4 V and up to 17 V. It is available in a 1.6 mm × 1.6 mm ×

0.55 mm, 6-lead LFCSP package and is rated to operate over the

+

VCC

5

+1

2

VEE

o

C to +85oC.

10µF

I

IDRV

ADA4800

22pF

7.5V

R
249kΩ

4

3

IDRV

IDRV

OUT

1kΩ10Ω

15V

09162-102

industrial temperature range of −40

ISF

R

7.5V

ISF

0.1µF

10kΩ
ISF

6

I

ISF

I

BUFF

I

1

AL

IN

49.9Ω

Figure 2. Typical Test Circuit

3V

Rev. A

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rights of third parties that may result from its use. Specifications subject to change without notice. No
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Tel: [phone] www.analog.com
Fax: [phone] ©2010 Analog Devices, Inc. All rights reserved.

ADA4800

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

Functional Block Diagram .............................................................. 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 3

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

Active Current Load Electrical Characteristics ........................ 3

Absolute Maximum Ratings ............................................................ 4

Thermal Resistance ...................................................................... 4

ESD Caution .................................................................................. 4

Pin Configuration and Function Descriptions ............................. 5

REVISION HISTORY

7/10—Rev. 0 to Rev. A

Deleted Figure 15 .............................................................................. 7

Changes to Setting Active Load Current with Pin 6 ISF Section

and Setting Bandwidth with Pin 4 (IDRV) Section ................... 10

6/10—Revision 0: Initial Version

Typical Performance Characteristics ..............................................6

Test Circuit .........................................................................................9

Theory of Operation ...................................................................... 10

Setting Active Load Current with Pin 6 (ISF) ........................ 10

Setting Bandwidth with Pin 4 (IDRV)..................................... 10

Applications Information .............................................................. 11

Open Source CCD Output Buffer ............................................ 11

Power Save Mode ....................................................................... 11

Power Supply Bypassing ............................................................ 12

Power Sequencing ...................................................................... 12

Outline Dimensions ....................................................................... 13

Ordering Guide .......................................................................... 13

Rev. A | Page 2 of 16

ADA4800

SPECIFICATIONS

BUFFER ELECTRICAL CHARACTERISTICS

TA = 25°C, VCC = 15 V, VEE = 0 V, R
unless otherwise noted (see Figure 2 for a test circuit).

Table 1.

Parameter Condition Min Typ Max Unit

GAIN

Voltage Gain VIN = 6.5 V to 8.5 V, R

INPUT/OUTPUT CHARACTERISTICS

I/O Offset Voltage 30 41 mV

IDRV Current R

Input/Output Voltage Range VEE + 1.4 VCC − 1.4 V

Input Bias Current (I

) 1 μA

BUFF

DYNAMIC PERFORMANCE

−3 dB Bandwidth R

R

R

Slew Rate V

Rise Time VIN = 7.5 V to 8.5 V, 10% to 90% 2.2 ns

Fall Time VIN = 8.5 V to 7.5 V, 10% to 90% 1.8 ns

1% Settling Time VIN = 9.5 V to 7.5 V (falling edge) 5 ns

V

V

V

I/O Delay Time VIN = 8.5 V to 7.5 V (falling edge) 0.4 ns

V

Output Voltage Noise @ 20 MHz 1.5 nV/√Hz

POWER SUPPLY

Supply Voltage Range 4 15 17 V

Supply Current (ICC) 1.4 1.8 mA

OPERATING TEMPERATURE RANGE −40 +85 °C

= 249 k connected to V

IDRV

= 249 kΩ, V

IDRV

= 300 kΩ (ICC = 1.1 mA), V

IDRV

= 150 kΩ (ICC = 2.1 mA), V

IDRV

= 50 kΩ (ICC = 4.7 mA), V

IDRV

= 2 V step 415 V/μs

OUT

= 7.5 V to 9.5 V (rising edge) 4.5 ns

IN

= 8.5 V to 7.5 V (falling edge) 4.5 ns

IN

= 7.5 V to 8.5 V (rising edge) 4 ns

IN

= 7.5 V to 8.5 V (rising edge) 0.35 ns

IN

, R

IDRV

IDRV

= 1 k in parallel with 22 pF in series with 10 , VIN = 7.5 V,

LOAD

= 0 Ω 0.995 0.998 1.005 V/V

ISF

= 15 V 52 59 μA

= 0.1 V p-p 182 MHz

OUT

= 0.1 V p-p 288 MHz

OUT

= 0.1 V p-p 400 MHz

OUT

ACTIVE CURRENT LOAD ELECTRICAL CHARACTERISTICS

TA = 25°C, VEE = 0 V, V

Table 2.

Parameter Condition Min Typ Max Unit

INPUT/OUTPUT CHARACTERISTICS

Active Load Current (IAL) V

V

ISF Current (I

) R

ISF

Input Voltage Range VEE + 1.7 VCC V

OPERATING TEMPERATURE RANGE −40 +85 °C

= 3 V, R

ISF

= 10 k connected to V

ISF

= 0 V 1 μA

ISF

V

= 3 V 3 mA

ISF

= 7.5 V 12.7 mA

ISF

= 10 kΩ 111 120 μA

ISF

, VIN = 7.5 V, unless otherwise noted (see Figure 2 for a test circuit).

ISF

Rev. A | Page 3 of 16

ADA4800

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 2.

Parameter Rating

Supply Voltage 18 V
Input Voltage VEE to VCC
ISF Pin VEE to VCC
IDRV Pin VEE to VCC
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +85°C
Junction Temperature Range −65°C to +150°C

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.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 3. Thermal Resistance

Package Type θJA Unit

6-Lead LFCSP 160 °C/W

ESD CAUTION

Rev. A | Page 4 of 16

ADA4800

A

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

DA4800

1

IN

ISF

6

VEE

OUT

NOTES

1. EXPOSED PAD IS NOT INTERNALLY
CONNECTED TO DIE. CONNECT TO ANY LOW
IMPEDANCE NODE O R LEAVE FLOATING.

EPAD

2

3

VCC

5

IDRV

4

09162-002

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 IN Input. Connect this pin to the CCD sensor output.
2 VEE Negative Power Supply Voltage.
3 OUT Output. Connect this pin to the AFE input.
4 IDRV

Bandwidth Adjustment Pin. Connect this pin to VCC or an external voltage with an external resistor. This pin
allows bandwidth to be controlled by adjusting I

. This pin can also be used to power down the buffer.

CC

5 VCC Positive Power Supply Voltage.
6 ISF

Active Load Current Adjustment Pin. Connect to VCC or an external voltage with an external resistor. This pin can
also be connected to the microcontroller logic output through an external resistor for power save mode. This pin
can also be used to power down the active current load.

EPAD EPAD Exposed Pad. Not internally connected to die. Connect to any low impedance node or leave floating.

Rev. A | Page 5 of 16