ANALOGDEVICES fAX-ON-DEMAND HOTLINE
-
Page
32
r-.
ANALOG
W
DEVICES
FEATURES
LowCost,3
1/2Digit
DPMfor OEM
Applications
AD2010
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LED Display with Latched Digital Outputs
Small Size, Ughtweight
Automatic Zero Correction; Max Error: 0.05% :t:1 Digit
High Normal Mode ReJection: 4OdB @ 50 or 60Hz
Optional Ratlometric Operation
leading "0" Display Blanking
5VDC Powered
APPLICATIONS
MedicaJ/ScientificlAnalytic Instruments
Data Acquisition Systems
Industrial Weighing Systems
Radouts in Engineering Units
Digi18l Thennometen
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GENERAL DESCRIPTION
Analog Devices' model AD2010 represents an advance in price!
performance capabilities of 3~ digit digital panel meters. The
AD20l0 offers O.OS%~l digit maximum error with bipolar,
single ended input, resolution of lO°StV, .and a common mode
rejection ratio of 60dB (CMRR) at %lOOm (CMV).
V
The AD20l0 features a light-cmitting-diode (LED) display
with a full scale range of 0 to ~l99.9 miRivolts, latched digital
data outputs and control interface signals, and leading zero dis-
play blanking. Automatic-zero correction circuitry measures
and compensates for offset and offset drift errors, thereby
providing virtually no error. Another useful feature of the
AD20l0 is its SV de operation. The AD20l0 can operate from
the users' SV de system supply, thereby eliminating the shield-
ing and dc:coupling needed for line powered units when the ac
line must be routed near signal leads.
To satisfy most application requirements, the conversion rate
of the AD2010 is normal1y 4 readings per second. However, an
external trigger may be applied to vary the sampling rates from
a maximum of 24 readings per second down to an indef'mite
hold time. The AD2010 can also be connected for automaric
conversion at its maximum conversion rate. During conversion,
the previous reading is held by the latched logic. The numeric
readout is available as BCD
da.ta.Applica.tion
of the metering
system in a computer or data logging system is made easy with
the availability of the "overrange," "polarity, It...overload,"
and "statUs" signals.
A simplified block diagram of the AD20l0, illustrating the
features described above is shown in Figure 1.
Foe detaikod information,
contact
&ctmy.
OLE
TE
ANAlOGSECTION
31Ii DIGIT A TO 0
DIGITAL SEA:TlCN
ANALOG IN
ANALOG GHD
/888
DIGITAL
GND
6Vdo
lieD
DATA
{
POu.RITY
SIGNAL
OVERl,QAI> SIGNAL
OVERRANaE SIGNAL
STATUS SIGNAl.
Figure
1.
Simplified
Functional
Block Diagram
IMPROVED NOISE IMMUNITY, ACCURACY AND
ZERO STABILITY
Dual-slope integration, as used in the AD2010 and as described
in the tbeory of operation section, offers several design benefits.
. Conversion accuracy, for example, is independent of both
the timing capacitor value and the clock frequency, since
they affect both the up ramp and down ramp integration
in the same ratio.
. Normal mode noise at line frequencies or its harmonics is
rejected since the average value of this noise is zero over the
integration period.
. To achieve Zero stability, a time interval during each conver-
sion is provided to allow the automatic-zero correction cir-
cuitry to measure and compensate for offset and offset drift
errors, thereby, providing virtUally no zero error.
REV. A
Infonnation 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 T~hnology Way, P,O. Box 9106, Norwood. MA 02062.9106, U.S.A.
Tel;
617/329-4700
Fax;
617/326.8703
Twx: 710/394-6577
Telex: 924491
Cable:
ANALOG NORWOODMASS
AHALOGDEVICES fAX-OH-DEMAHD HOTLIHE
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Page
33
AD201-SPECIFICATIONS
0
DISPLAY OUJ'PUT
(typical
at +25°C and +5V de unlessotherwisenoted)
Maximum
Conversion
Rate
-
Automatic
- The
AD2010
. Display
consists
offourLED's
0.27"
(
(6.9mm)
high).
can also be connected
for automatic
conversion
at its
fOl"data digits plus 100'11.
overrange and polarity
indication.
. Overload
- three
.
data digits display zeros
and flashes.
Decimal Points - selectable at input connector.
controlled
externally.
. Leading Display
"0"
Blanking
-
INPUT
. Full Scale Range - 0 to :1:199.9millivolts
. Automatic Zero
. Automatic Polarity
maximum conversion rare by connecting the "Status"
output back into the "hold" input. In this manner the
status signal going high at the end of one conversion
immediately initiates a new conversion. The pu!$es
appearing on the status line can be used to step a
multiplexer directly, since the built-in drift-correCt
delay of 8.33ms will aRow settling of the input prior
to convCtsion. A logic "0" applied to the "EXT TRIGGER"
will inhibit [he automatic trigger mode.
EXtetnal
Hold
-
Logic
"0"
or ground
applied
to this in.
. BiasCurrent
-
.
.
3nA
OBS
. MaximumError -0.05% ofreading:l:l digit
DC Impcciance - l00MD
Overvoltage Protection - 20V sustained, 50V momentary
without damage.
. Decimal Points (3) - illuminate with logic "1", extin-
guish with logic "0".
ACCURACY
. Resolution
- 0.1
put disables the internal trigger an~ the last conversion is
held and displayed. For a new conversion under internal
control the input must be opened or at logic "1", For a
new conversion under external control, a positive pulse
of less than 1.0ms can be applied (as previously explained).
OUTPUTS
. 3 BCD DigitS (8421 Positive True) .latched - 3TTL loads
. Overrange -logic "." - latched - 6TTL loads, indicates
millivolt
. T~pera[Ure Range- 0 to +SO°C
operating
Temperature Coefficient
. Overload
.logic
"0"
overrange.
indicates
overload
(>199.9mV)
-30°C to +8SoC storage
.
-
:tSOppm/oC
NORMAL MODE REJECfION
COMMON MODE REJECTION
6OdB @ :t200mV
CONVERSION
.
Internal
RATE
.
.
4OdB @ 60Hz
. External
-
up
Trigger
to
24
conversions
per
second
. Automatic
new
-
A
Trigger - 4 conversions
conversion
per second
is initiated
automatically
upon completion of conversion in procC$S; conversion
rate wiD vary from
24/Kc
(0
4O/sec
depending on input
magnitude.
. Holdand Readupon command.
CONVERSION TIME
. Overload Conversion - 62ms max
INTERFACE SIGNALS
. DTLITTL Compatible
. Normal
Conversion
- 42ms
max
(full
scale
input)
. InputS
logic"0"
logic "I"
IN
<0.8V
>2.0V
OUT
<0.4V
>2.4V
OLE
TE
ORDERING GUIDE
. AD2010' Standard AD2010 as described above - tUned
for peak normal mode rejection at 60Hz and itS
harmonics.
WEIGHT
. 4 oz. (113.Sgm)
logic "I" -latched. 6TTL loads, indicates.
data valid.
. Polarity - logic "I" -latched - 6TTL loads. indicates
positive polarity input.
. Status -logic "0" - conversion in process
logic
"I" -latched - 6TTL loads, indicates con-
version complete:.
POWER
.
+SV
dc :1:5%, 0OmA
5
WARM UP
. Essentially none to specified accuracy
ADJUSTMENTS
. Range potentiometer for full scale calibration. Calibra-
tion recommended every six months.
SIZE
. 3"W x 1.8MHx 0.84"D (76.2 x 45.7 x 21.3mm) (overall
depth for case and printed circuit board extension is
1.40" (35.6mm».
External Trigger - Operation in the "External Trigger"
mode requires that the "EXternal Hold" input be a logic
"0" or sround.
Neptive Triaer Pulses - Applying a logical "low" to
the "HOLD" input disables the internal trigger. A
negative trigger pulse (logic "I" to logic "0") of
1.0p.s minimum applied to the "EXT TRIGGER" in-
put will initiate conversion in the same manner as the
internal oscillator. The eXternal trigger should not be
repeated, however, until the "status" indicates com-
pletion of the convetsion in process.
Positive
Trigger
Pulses
OVERALL DIMENSIONS
All dimensions are given in inches and (nun).
PIN "A"
,"--'
PIN "S"
~0.30t7.62IM'N.
-
The
"HOLD"
input
can be .
~
1.41
~
.
1
used to trigger the AD20 10 from a "normally low"
signal with the "EXT TRIGGER" input open or logic "1".
Following a "hold" a new reading will be initiated on the
leading edge of the "hold" signal Thus, a mo~ntary
positive pulse on the "HOLD" input can be used to
trigger the AD201O. The drift correct interval, how-
ever, begins on the trailing edge of the positive pulse,
so if [he pulse width exceeds 1ms, the conversion will
actually be initiated by the internal trigger.
L
---,
0.840
(21.31 MAX.
--1
!:TaG j3.94} MAX.
11--
I---
3.020 (78.7)'~~. ---J
..
-3.420 188.8)MAX.--j
Specifications subjeCt to ebanJe without notice.
NORMAL MODE
ADJUSTMENT
(AD201OR ONLY)
-2-
REV. A
模拟电子
