a
Complete 12-Bit 10 MSPS
Monolithic A/D Converter
AD872A
PRODUCT DESCRIPTION
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND AVSS
DVDD
DGND *DRVDD *DRGND
AD872A
VINA
VINB
+
T/H
DAC
A/D
CLOCK
+
T/H
DAC
A/D
4
+
T/H
DAC
A/D
4
A/D
3
4
TE
CORRECTION LOGIC
REF IN
REF OUT
+2.5V
REFERENCE
OUTPUT BUFFERS
REF GND
OTR MSB *MSB
BIT2–BIT12
*OEN
*ONLY AVAILABLE ON 44-TERMINAL SURFACE MOUNT PACKAGE
LE
FEATURES
Monolithic 12-Bit 10 MSPS A/D Converter
Low Noise: 0.26 LSB RMS Referred-to-Input
No Missing Codes Guaranteed
Differential Nonlinearity Error: 0.5 LSB
Signal-to-Noise and Distortion Ratio: 68 dB
Spurious-Free Dynamic Range: 75 dB
Power Dissipation: 1.03 W
Complete: On-Chip Track-and-Hold Amplifier and
Voltage Reference
Twos Complement Binary Output Data
Out-of-Range Indicator
28-Lead Ceramic DIP or 44-Terminal Leadless Chip
Carrier Package
The AD872A is fabricated on Analog Devices’ ABCMOS-l
process that utilizes high speed bipolar and CMOS transistors
on a single chip.
The AD872A is packaged in a 28-lead ceramic DIP and a 44terminal leadless ceramic surface mount package (LCC). Operation is specified from 0°C to +70°C and –55°C to +125°C.
B
SO
The AD872A is a monolithic 12-bit, 10 MSPS analog-to-digital
converter with an on-chip, high performance track-and-hold
amplifier and voltage reference. The AD872A uses a multistage
differential pipelined architecture with error correction logic to
provide 12-bit accuracy at 10 MSPS data rates and guarantees
no missing codes over the full operating temperature range. The
AD872A is a redesigned version of the AD872 which has been
optimized for lower noise. The AD872A is pin compatible with
the AD872, allowing the parts to be used interchangeably as system requirements change.
O
The low noise input track-and-hold (T/H) of the AD872A is
ideally suited for high-end imaging applications. In addition, the
T/H’s high input impedance and fast settling characteristics allow the AD872A to easily interface with multiplexed systems
that switch multiple signals through a single A/D converter. The
dynamic performance of the T/H also renders the AD872A suitable for sampling single channel inputs at frequencies up to and
beyond the Nyquist rate. The AD872A provides both reference
output and reference input pins, allowing the onboard reference
to serve as a system 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 twos complement binary output format. An out-ofrange signal indicates an overflow condition, and can be used
with the most significant bit to determine low or high overflow.
PRODUCT HIGHLIGHTS
The AD872A offers a complete single-chip sampling, 12-bit
10 MSPS analog-to-digital conversion function in a 28-lead DIP
or 44-terminal LCC.
Low Noise—The AD872A features 0.26 LSB rms referred toinput noise.
Low Power—The AD872A at 1.03 W consumes a fraction of the
power of presently available hybrids.
On-Chip Track-and-Hold (T/H)—The low noise, high impedance T/H input eliminates the need for external buffers and can
be configured for single-ended or differential inputs.
Ease of Use—The AD872A is complete with T/H and voltage
reference and is pin-compatible with the AD872.
Out of Range (OTR)—The OTR output bit indicates when the
input signal is beyond the AD872A’s input range.
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1997
