FUNCTIONAL BLOCK DIAGRAM
AIN BPO/UPO ENCODE REF IN ACOM DCOM
LATCHES
CORRECTION LOGIC
RANGE
SELECT
X4
COARSE
4-BIT
FLASH
8-BIT
LADDER
MATRIX
FINE
4-BIT
FLASH
AD671
3
4
48
12
20
DAC
OTR MSB BIT1-12 DAV
21 16 19 23 22 24 17 18
3-BIT
FLASH
3
DAC
3-BIT
FLASH
14 13 1512 1
V
CC
V
LOGICEE
V
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.
a
Monolithic 12-Bit
2 MHz A/D Converter
AD671
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
FEATURES
12-Bit Resolution
24-Pin “Skinny DIP” Package
Conversion Time: 500 ns max—AD671J/K/S-500
Conversion Time: 750 ns max—AD671J/K/S-750
Low Power: 475 mW
Unipolar (0 V to +5 V, 0 V to +10 V) and Bipolar Input
Ranges (65 V)
Twos Complement or Offset Binary Output Data
Out-of-Range Indicator
MIL-STD-883 Compliant Versions Available
PRODUCT DESCRIPTION
The AD671 is a high speed monolithic 12-bit A/D converter
offering conversion rates of up to 2 MHz (500 ns conversion
time). 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 avail-
able hybrid implementations. Additionally, the greater reliability
of monolithic construction offers improved system reliability
and lower costs than hybrid designs.
The AD671 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 pro-
vides strobe pulses for each of the four internal flash cycles and
assures adequate settling time for the interflash residue ampli-
fier. A single ENCODE pulse is used to control the converter.
The performance of the AD671 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 AD671 is available in two conversion speeds and perfor-
mance grades. The AD671J and K grades are specified for op-
eration over the 0°C to +70°C temperature range. The AD671S
grades are specified for operation over the –55°C to +125°C
temperature range. All grades are available in a 0.300 inch wide
24-pin ceramic DIP. The J and K grades are also available in a
24-pin plastic DIP.
PRODUCT HIGHLIGHTS
1. The AD671 offers a single chip 2 MHz analog-to-digital
conversion function in a space saving 24-pin DIP.
2. Input signal ranges are 0 V to +5 V and 0 V to +10 V unipo-
lar, and –5 V to +5 V bipolar, selected by pin strapping. In-
put resistance is 1.5 kΩ. Power supplies are +5 V and –5 V,
and typical power consumption is less than 500 mW.
3. The external +5 V reference can be chosen to suit the dc ac-
curacy and temperature drift requirements of the application.
4. Output data is available in unipolar, bipolar offset or bipolar
twos complement binary format.
5. An OUT OF RANGE output bit indicates when the input
signal is beyond the AD671’s input range.
6. The AD671 is available in versions compliant with the MIL-
STD-883. Refer to the Analog Devices Military Products
Databook or current AD671/883B data sheet for detailed
specifications.