Analog Devices AD9823 Datasheet

Correlated Double Sampler (CDS)

FEATURES

40 MHz correlated double sampler (CDS)
Fixed 3.5 dB CDS gain
Low noise optical black clamp circuit
3 V single-supply operation
14-lead TSSOP package

APPLICATIONS

Digital still cameras
Digital video camcorders
CCTV cameras
PC cameras
Portable CCD imaging devices

CCDIN

BYP2

CLP

AD9823

FUNCTIONAL BLOCK DIAGRAM

AD9823

3.5dB FIXED GAIN

CDS

CLP

INTERNAL

TIMING

SHDSHP

Figure 1. Functional Block Diagram

INTERNAL

REFERENCE

OUTPUT
BUFFER

OUTPUT
BUFFER

BYP3BYP1

OUTPUT

REFOUT

VDD

GND

04538-0-001

PRODUCT DESCRIPTION

The AD9823 is a correlated double sampler for digital camera
applications. It features a 40 MHz CDS amplifier with 3.5 dB of
fixed gain, an internal voltage reference supply, and timing
control for the SHP and SHD sampling clocks. Output buffers
are also included, providing drive strength for PCB traces and
direct connection to an image signal processor such as the
AD9821.

The AD9823 is ideal for applications that need to place the CDS
and VGA/ADC circuits on separate PC boards. The “pseudo
differential” outputs of the AD9823 provide good signal
integrity when interfaced with the differential input AD9821.

The AD9823 operates from a single 3 V power supply, typically
dissipates 50 mW, and is packaged in a 14-lead TSSOP package.

Rev. 0

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Specifications subject to change without notice. No license is granted by implication
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AD9823

TABLE OF CONTENTS

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

General Specifications ................................................................. 3

Analog Specifications................................................................... 3

Digital Specifications ................................................................... 3

Timing Specifications .................................................................. 4

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

REVISION HISTORY

Revision 0: Initial Version

Thermal Characteristics ...............................................................5

ESD Caution...................................................................................5

Pin Configuration and Function Descriptions..............................6

SHP and SHD Timing ..................................................................6

Outline Dimensions..........................................................................8

Ordering Guide .............................................................................8

Rev. 0 | Page 2 of 8

AD9823

T

SPECIFICATIONS

GENERAL SPECIFICATIONS

Table 1.

Parameter Min Typ Max Unit

Temperature Range

Operating –25 +85 °C

Storage –65 +150 °C
Power Supply Voltage 2.7 3.6 V
Power Consumption: f
Maximum Clock Rate 40 MHz
Minimum Clock Rate 5 MHz

ANALOG SPECIFICATIONS

Table 2. T

Parameter Min Typ Max Unit Notes

Analog Input (CCDIN)

Max Input Range Before Saturation1 850 mV p-p

Allowable CCD Reset Transient1 500 mV
Max CCD Black Pixel Amplitude1 100 mV
Gain 2.5 3.5 4.5 dB
Nonlinearity, 500 mV Input 1.0 % Max deviation from ideal straight line
Input Referred Noise 100 µV rms Output noise divided by 3.5 dB gain
Clamp Time Constant 190 µsec 0.1 µF BYP2 capacitor (proportional to capacitor value)
Analog Outputs

Typical Data Out Signal Range 0.5 1.5 V 0.5 V corresponds to black level

REFOUT Voltage Level 0.5 V Fixed dc reference for signal output

1

Input signal characteristics defined as follows:

MIN

to T

= 40 MHz, VDD = 3.0 V 50 mW

SAMP

, VDD = 3.0 V, f

MAX

= 40 MHz, unless otherwise noted.

SAMP

500mV TYP

RESET TRANSIEN

All specifications subject to change without notice.

100mV TYP

OPTICAL BLACK PIXEL

850mV TYP

INPUT SIGNAL RANGE

04538-0-002

DIGITAL SPECIFICATIONS

Table 3.

Parameter Symbol Min Typ Max Unit

Logic Inputs (SHP, SHD, CLP)

High Level Input Voltage VIH 2.1 V

Low Level Input Voltage VIL 0.6 V

High Level Input Current IIH 10 µA

Low Level Input Current IIL 10 µA

Input Capacitance CIN 10 pF

Rev. 0 | Page 3 of 8