Monolithic 12-Bit 5 MSPS A/D Converter
Low Noise: 0.17 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: 73 dB
Power Dissipation: 1.03 W
Complete: On-Chip Track-and-Hold Amplifier and
Pin Compatible with the AD872
Twos Complement Binary Output Data
Out of Range Indicator
28-Lead Side Brazed Ceramic DIP or 44-Terminal
Surface Mount Package
Complete 12-Bit 5 MSPS
Monolithic A/D Converter
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND AVSS
T/H T/H T/H
OTR *MSB MSB–BIT 12
*ONLY AVAILABLE ON 44 -TERMINAL SURFACE MOUNT PACKAGE
The AD871 is a monolithic 12-bit, 5 MSPS analog-to-digital
converter with an on-chip, high performance track-and-hold
amplifier and voltage reference. The AD871 uses a multistage
differential pipelined architecture with error correction logic to
provide 12-bit accuracy at 5 MSPS data rates and guarantees no
missing codes over the full operating temperature range. The
AD871 is a redesigned variation of the AD872 12-bit, 10 MSPS
ADC, optimized for lower noise in applications requiring sam-
pling rates of 5 MSPS or less. The AD871 is pin compatible
with the AD872, allowing the parts to be used interchangeably
as system requirements change.
The low-noise input track-and-hold (T/H) of the AD871 is ide-
ally suited for high-end imaging applications. In addition, the
T/H’s high input impedance and fast settling characteristics
allow the AD871 to easily interface with multiplexed systems
that switch multiple signals through a single A/D converter. The
dynamic performance of the input T/H also renders the AD871
suitable for sampling single channel inputs at frequencies up to
and beyond the Nyquist rate. The AD871 provides both refer-
ence output and reference input pins, allowing the onboard ref-
erence 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-of-
range signal indicates an overflow condition, and can be used
with the most significant bit to determine low or high overflow.
The AD871 is fabricated on Analog Devices’ ABCMOS-1 pro-
cess, which uses high speed bipolar and CMOS transistors on a
single chip. High speed, precision analog circuits are now com-
bined with high density logic circuits.
The AD871 is packaged in a 28-lead ceramic DIP and a
44-terminal leadless ceramic surface mount package and is
specified for operation from 0°C to +70°C and –55°C to
The AD871 offers a complete single-chip sampling 12-bit,
5 MSPS analog-to-digital conversion function in a 28-lead DIP
or 44-terminal leadless ceramic surface mount package (LCC).
Low Noise—The AD871 features 0.17 LSB referred-to-input
noise, producing essentially a “1 code wide” histogram for a
code-centered dc input.
Low Power—The AD871 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 imped-
ance T/H input eliminates the need for external buffers and can
be configured for single ended or differential inputs.
Ease of Use—The AD871 is complete with T/H and voltage ref-
erence and is pin-compatible with the AD872 (12-bit, 10 MSPS
Out of Range (OTR)—The OTR output bit indicates when the
input signal is beyond the AD871’s input range.
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.
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© Analog Devices, Inc., 1997