DAS1159_15 Datasheet, PDF (4/4 Pages) Analog Devices – LowPower14-B-it,15Bit& 16-Bit SamplingAnalog-to-DigitaClonverters

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DAS1157IDAS1158IDAS1159
GAIN AND OFFSET ADJUSTMENT
The DASII 57/DAS1158/DAS1159 contain internal gain and
offset adjusanent potentiometers. Each potentiometer bas ample
- Input Voltap Output Code Reiatiouhips
Unipolar Input Voltaaa
adjustment range so that pin and offset errors can be trimmed
to zero.
AAaloSlnput
Oto +SVRange Oto + 10VItaqe
Di,itat Output
Offset calibration is not affected by changes in pin calibration,
and should be performed prior to gain calibration. Proper gain
and offset calibration requires great care and the use of atremdy
sensitive and accurate reference instrUmCD.tsT. he voltage standard
used as a signal source must be very stable and be capable of
being set to within ~ l/lOLSB of the desired value at any point
within its range.
OFFSET CALIBRATION
For a 0 to + 10V unipolar range, set the input voltage precisely
DASI157
+4.99969V
+ O.OOOOOV
DAS1l58
+4.99985V
+O.OOOOOV
DAS1l59
+4.99992V
+O.OOOOOV
+ 9. 99939V
+ O.OOOOOV
+9.99969V
+O.OOOOOV
+9.99985V
+ O.OOOOOV
Binary Code
II 1111 1111 1111
00 0000 0000 0000
Binary Code
III IIII 1111 1111
000 0000 0000 0000
Modified Binary Code
0111 1111 1111 1111
1000 0000 0000 0000
OBSOLETE to +305fJV. for the DASllS7, + IS3fJV. for the DAS1158and
+ 76fJ.Vfor the DAS1l59. For a 0 to +5V unipolar range, set
the input to + 153fJ.Vfor the DAS1l57, + 76fJ.Vfor the DAS1158
and + 38fJ.Vfor the DAS1159. Then adjust the zero potentiometer
until the converter is just on the verge of switching from
000 000 to 000 001 (DAS1157/DASI158) or from
100 000 to 100 001 (DAS1159).
For the ~ 5V bipolar range, set the input voltage precisely to
+ 305fJV. for the DAS1l57, + 153fJV. for the DAS1l58 and
+ 76fJ.Vfor the DASIl59. For a ~ lOV bipolar range, set the
input voltage precisely to +610fJ.Y for the DASllS7, +305fJ.V
for the DAS1l58 and + 153fJ.Vfor the DAS1I59. Adjust the
zero potentiometer until the offset binary coded units are jUSt
on the verge of switching from 000 000 to 000 001
and the tWo'Scomplement coded units are just on the verge of
switching from 100 000 to 100 001.
GAIN CALIBRATION
Set the input voltage precisely to + 9.99909V (DAS1l57)1
Table II. Unipolar Input-Output Relationships
AAaIoI "'put
" SV
" ItV ........
DASIIS7
+4.99939Y
+9.9987&Y
+ O.OOOOOY
+O.OOOOOY
- S.OOOOOY
- 10.OOOOOY
DASI IS&
+4.99969V
+9.99939Y
+O.OOOOOY
- S.OOOOOY
+O.OOOOOY
- 10.OOOOOY
DASIJS9
+4.99985Y
+'1.99969V
+O.OOOOOY
+O.OOOOOY
- S.OOOOOY
- 10.OOOOOY
Bipolar"'pat voltaaa
DIptaJ 00njNt
Oft_IliauyCodo
T_'.c-pic-Cook
II 1111 \III 1111
I0 0000 0000 0000
00 0000 0000 0000
01 1111 1111IIJI
00 0000 0000 0000
I0 0000 0000 0000
II I 1111 1111 I \II
I00 0000 0000 0000
000 0000 0000 0000
011 1111 1111 1111
000 0000 0000 0000
100 0000 0000 0000
0111 1111 1111 ]]11
0000 0000 0000 0000
I000 0000 0000 0000
Table III. Bipolar Input-Output Relationships
TRI-STATE DIGITAL OUTPUT
The ADC digital outputs are provided in parallel format to the
output tri-state buffers. The output infonnation can be applied
+9.99954V (DAS1l58)1 + 9.99977V (DAS1159) for the 0 to
+ lOV units, +4.99954V (DASI157)/ +4.99977V (DASI158)1
to a data bus in either a one-byte or a tWo-byte format by using
the HIGH BYTE ENABLE and LOW BYTE ENABLE tenninals.
+4.99989V (DAS1159) for 0 to + 5V units, +9.998l7V
(DAS 1157)/+ 9.99909V (DAS 1158)1+ 9. 99954V (DAS1159) for
If the tn-state feature is not required, normal digital outputs
can be obtained by connecting the enable pins to ground.
~ IOVunits, or + 4.99909V(DASl157)/+ 4.99954V(DASI158)/
+4.99977V (DAS1l59) for ~5V units. Note that these values
are I 1/2LSBs less than nominal full scale. Adjust the gain
potentiometer until binary and offset binary coded unitS are just
on the verge of switching from 11 10 to 11 11 or modified
binary and tWo's complement coded units are just on the verge
of switching from 011 10 to 011 11.
POWER SUPPLY AND GROUNDING CONNECTIONS
No power supply decoupling is required since the DAS1l57/
DASI 158/DASI 159 contain high quality tantalum capacitors on
each of the power supply inputs to ground.
The analog and digital grounds are internally connected in the
DAS1l57/DAS1158/DAS1l59. But in many applications, an
DAS1157IDASnS8IDAS1159 INPUT/OUTPUT
RELATIONSIUPS
external connection betWeen the digital ground pin and analog
ground pin is advisable for optimum performance.
The DAS1l57IDAS1I58 produces a true binary coded output
when configured as a unipolar device. Configured as a bipolar
device, it can produce either offset binary or tWo's complement
outpUt codes. The most significant bit (MSB) is used to obtain
the binary and offset binary codes while (MSB) is used to obtain
two's complement coding. The DAS1159 produces a modified
binary coded output when configured as a unipolar device.
Configured as a bipolar device it can only produce two's com-
plement output codes. The DAS1159 uses MSB to obtain the
DIGITAL
PO_II
SUPPl.V
COMMON
STAR.1'OJfn"OF
DIG_, ITALOIlOUNOS
, STAR-POINTOF
ANALOGGIIOVNDS
:.
I DlGIT'IL
I GIIOVND
'IN.f.LOG
GROUNDI
I
I
I OAS11S7IOAS11581OA$1159I
I
I
"
)
ANAUXi
S'OVWt>El'Rl.Y
roMMO"
modified binary and two's complement output codes; the DASll59
duc~ not have an MSB output. Table II shows the DASllS7/
DAS1158/DAS1l59 unipolar analog input/digital output re-
lauonships. Table HI shows the DAS1l57/DAS1l581DAS1l59
Figure 4. Tvpical Ground Lavout for DAS1157/DAS1158/
DASl159
btpolar analog input/digital outpUt relationships.
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