AD7555_15 Datasheet, PDF (1/12 Pages) Analog Devices – Digit ADC Subsystem

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ANALOG
DEVICES
--
CMOS
4Y2/5Y2 Digit ADCSubsystem
PRELIMINARY TECHNICAL DATA
FEATURES
Resolution: :1:41/2 Digits BCD or f20k Count Binary Capa-
bility for 5 1/2 Digit Resolution or Custom Data Formats
Data Format: Multiplexed BCD (for Display) and Serial Count
."
(for External Linearization, Data Reformatting, or Micro-
processor Interface)
Accuracy: :1:1Count in :l:20k Counts
Scale Factor Drift: 0.2ppmfC- Using Only Medium-
Precision Op Amps
Requires only a Single Positive Reference
Overrange Display
Auto Calibration Capability
Interfaces to TTL or 5V CMOS
OHOLD Input and SCC (System Conversion Complete)
Output for Interface Flexibility
B _{GENERAL DESCRIPTION}
S The AD7555 is a 4 1/2 digit, monolithic CMOS, quad slope
integrating ADC subsystem designed for display or micro-
O _{processor interface applications. Use of the high resolution}
enable input expands the display form~t to 5 1/2 digits BCD.
8 ^{L With SCO (Serial Count Out) connected to SCI (Serial Count}
E _{In), the output data format is multiplexed BCD suitable for}
visual display purposes. As an added featUre, SCO can also be
TE _{used with rate multipliers for linearization, or with BCD or}
AD7555 FUNCTIONAL DIAGRAM
binary counters for data reformatting (up to 200k binary
counts).
VREF> ( 1
The quad slope conversion algorithm (Analog Devices patent
No. 3872466) converts the external amplifier's input drift
errors to a digital number and subsequently reduces the total
system drift error to a second order effect. Using only inex-
pensive, medium-precision amplifiers a scale factor drift of
o.2ppmf C is achieved.
~
PIN CONFIGURATION
. VREF> f1l
, os . Do,
DATA STROBE
,B8 B4, B2 BJ ,
BCD DATA
AD7555
TOP VIEW
--^{ORDERING INFORMA nON}
Model
Package
T
.
i⁰ peratmg
I Temperature
~~-
Range
"
--^AD75,-^55B--^{D 28 Pin Side Brazed Ceramic-.j -2--5-°C to +85°C}
AD7555KN 28 Pin Molded Plastic
0 to +70oC
-- ~
15$1C1
8
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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 implica-
tion or otherwise under any patent or patent rights of Analog Devices.
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