a
FEATURES
Conversion Time: 800 ns
1.25 MHz Throughput Rate
Complete: On-Chip Sample-and-Hold Amplifier and
Voltage Reference
Low Power Dissipation: 570 mW
No Missing Codes Guaranteed
Signal-to-Noise Plus Distortion Ratio
fIN = 100 kHz: 70 dB
Pin Configurable Input Voltage Ranges
Twos Complement or Offset Binary Output Data
28-Pin DIP and 28-Pin Surface Mount Package
Out of Range Indicator
Complete 12-Bit 1.25 MSPS
Monolithic A/D Converter
AD1671
FUNCTIONAL BLOCK DIAGRAM
SHA
OUT
5k
UPO/BPO
VCC
VEE
ACOM
VLOGIC
DCOM
S/H
AIN1
RANGE
SELECT
AIN2
5k
3-BIT
FLASH
DAC
3
REF IN
REF OUT
ENCODE
X4
3-BIT
FLASH
DAC
8-BIT
LADDER
MATRIX
COARSE
4-BIT
FLASH
3
4
FINE
4-BIT
FLASH
CORRECTION LOGIC
2.5V
REF
4
8
LATCHES
AD1671
REF COM
PRODUCT DESCRIPTION
The AD1671 is a monolithic 12-bit, 1.25 MSPS analog-todigital converter with an on-board, high performance sampleand-hold amplifier (SHA) and voltage reference. The AD1671
guarantees no missing codes over the full operating temperature range. The combination of a merged high speed bipolar/
CMOS process and a novel architecture results in a combination of speed and power consumption far superior to previously available hybrid implementations. Additionally, the
greater reliability of monolithic construction offers improved
system reliability and lower costs than hybrid designs.
The fast settling input SHA is equally suited for both multiplexed systems that switch negative to positive full-scale
voltage levels in successive channels and sampling inputs at
frequencies up to and beyond the Nyquist rate. The AD1671
provides both reference output and reference input pins, allowing the on-board 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.
The AD1671 uses a subranging flash conversion technique,
with digital error correction for possible errors introduced in
the first part of the conversion cycle. An on-chip timing generator provides strobe pulses for each of the four internal
flash cycles. A single ENCODE pulse is used to control the
converter. The digital output data is presented in twos
complement or offset binary output format. An out-of-range
signal indicates an overflow condition. It can be used with
the most significant bit to determine low or high overflow.
12
OTR
MSB
BIT 1 –12
DAV
The performance of the AD1671 is made possible by using high
speed, low noise bipolar circuitry in the linear sections and low
power CMOS for the logic sections. Analog Devices’ ABCMOS-1
process provides both high speed bipolar and 2-micron CMOS
devices on a single chip. Laser trimmed thin-film resistors are
used to provide accuracy and temperature stability.
The AD1671 is available in two performance grades and three
temperature ranges. The AD1671J and K grades are available
over the 0°C to +70°C temperature range. The AD1671A grade
is available over the –40°C to +85°C temperature range. The
AD1671S grade is available over the –55°C to +125°C temperature range.
PRODUCT HIGHLIGHTS
The AD1671 offers a complete single chip sampling 12-bit,
1.25 MSPS analog-to-digital conversion function in a 28-pin
package.
The AD1671 at 570 mW consumes a fraction of the power of
currently available hybrids.
An OUT OF RANGE output bit indicates when the input signal is beyond the AD1671’s input range.
Input signal ranges are 0 V to +5 V unipolar or ± 5 V bipolar,
selected by pin strapping, with an input resistance of 10 kΩ.
The input signal range can also be pin strapped for 0 V to +2.5 V
unipolar or ±2.5 V bipolar with an input resistance of 10 MΩ.
Output data is available in unipolar, bipolar offset or bipolar
twos complement binary format.
REV. B
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: 617/329-4700
Fax: 617/326-8703
