AD9225 Datasheet, PDF (1/24 Pages) Analog Devices – Complete 12-Bit, 25 MSPS Monolithic A/D Converter

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FEATURES
Monolithic 12-Bit, 25 MSPS A/D Converter
Low Power Dissipation: 280 mW
Single +5 V Supply
No Missing Codes Guaranteed
Differential Nonlinearity Error: ؎0.4 LSB
Complete On-Chip Sample-and-Hold Amplifier and
Voltage Reference
Signal-to-Noise and Distortion Ratio: 71 dB
Spurious-Free Dynamic Range: –85 dB
Out-of-Range Indicator
Straight Binary Output Data
28-Lead SOIC
28-Lead SSOP
Compatible with 3 V Logic
Complete 12-Bit, 25 MSPS
Monolithic A/D Converter
AD9225
FUNCTIONAL BLOCK DIAGRAM
VINA
VINB
CAPT
CAPB
VREF
SENSE
SHA
CLK
AVDD
DRVDD
MDAC1
GAIN = 16
MDAC2
GAIN = 4
MDAC3
GAIN = 4
5
A/D
3
A/D
3
A/D
5
3
3
DIGITAL CORRECTION LOGIC
12
OUTPUT BUFFERS
A/D
4
MODE
1V
SELECT
REFCOM
AVSS
AD9225
DRVSS CML
OTR
BIT 1
(MSB)
BIT 12
(LSB)
PRODUCT DESCRIPTION
The AD9225 is a monolithic, single supply, 12-bit, 25 MSPS,
analog-to-digital converter with an on-chip, high performance
sample-and-hold amplifier and voltage reference. The AD9225
uses a multistage differential pipelined architecture with output
error correction logic to provide 12-bit accuracy at 25 MSPS
data rates, and guarantees no missing codes over the full operat-
ing temperature range.
The AD9225 combines a low cost high speed CMOS process
and a novel architecture to achieve the resolution and speed of
existing bipolar implementations at a fraction of the power
consumption and cost.
The input of the AD9225 allows for easy interfacing to both
imaging and communications systems. With a truly differential
input structure, the user can select a variety of input ranges and
offsets including single-ended applications. The dynamic perfor-
mance is excellent.
The sample-and-hold (SHA) amplifier is well suited for both
multiplexed systems that switch full-scale voltage levels in suc-
cessive channels and sampling single-channel inputs at frequen-
cies up to and well beyond the Nyquist rate.
The AD9225’s wideband input combined with the power and
cost savings over previously available monolithics, is suitable for
applications in communications, imaging and medical ultrasound.
The AD9225 has an onboard programmable reference. An
external reference can also be chosen to suit the dc accuracy and
temperature drift requirements of the application.
A single clock input is used to control all internal conversion
cycles. The digital output data is presented in straight binary
output format. An out-of-range signal indicates an overflow
condition that can be used with the most significant bit to deter-
mine low or high overflow.
PRODUCT HIGHLIGHTS
The AD9225 is fabricated on a very cost effective CMOS
process. High-speed precision analog circuits are now combined
with high density logic circuits.
The AD9225 offers a complete single-chip sampling 12-bit,
25 MSPS analog-to-digital conversion function in 28-lead SOIC
and SSOP packages.
Low Power—The AD9225 at 280 mW consumes a fraction of
the power of presently available in existing monolithic solutions.
On-Board Sample-and-Hold (SHA)—The versatile SHA
input can be configured for either single-ended or differential
inputs.
Out of Range (OTR)—The OTR output bit indicates when
the input signal is beyond the AD9225’s input range.
Single Supply—The AD9225 uses a single +5 V power supply
simplifying system power supply design. It also features a sepa-
rate digital driven supply line to accommodate 3 V and 5 V logic
families.
Pin Compatibility—The AD9225 is pin compatible with the
AD9220, AD9221, AD9223 and AD9224 ADCs.
REV. A
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© Analog Devices, Inc., 1998