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AS8501 - Data Sheet
austriamicrosystems
Revision 1.1, 04-April-06
www.austriamicrosystems.com
Page 22 of 40
7.5.6
CAR calibration register ( 110 bits )
The calibration register holds the calibration constants that are used by the internal DSP for the correction of each
measurement. At power-up sequence the Zener-Zap subregister ZCL is copied into the CAR register as shown in fig.
7.4.6.1. The register can be read or written in mode 8 via the SDI bus at any time. In particular it is possible to write
preliminary calibration constants with CAR or overwrite the loaded ZCL data, if a calibration has been changed.
Nr.
CAR bits
109-99 98-88
87-77 76-66
65-55 54-44
43-33 32-22
21-11
10-0
NOTE
0
Subregister
CGI1
CGI2
CGI3
CGI4
CAU0 CAU1 CAU2 CAU3 CAU4 CAU5 1), 2)
1
default
1548
Notes:
1)
Calibration register is composed of the following constants each having 11 bits:
CGI1, CGI2, CGI3, CGI4, CAU0, CAU1, CAU2, CAU3, CAU4, CAU5
2)
This register can be read or written at any time via the SDI bus. In particular it is possible to write
preliminary
calibration constants with CAR or overwrite the loaded ZCL data, if a calibration has been
changed.
7.5.7
TRR trimming register ( 20 bits )
In the TRR register the calibration constants for the reference voltage, for the amplifier-offset trim and for the current source setting are stored.
At power-up sequence the Zener-Zap subregister ZTR is loaded into the TRR register. This register can be read or written in mode 8 via the
SDI bus. In particular it is possible to write preliminary calibration constants into TRR or overwrite the loaded ZTR data, if a calibration has been
changed. The trimming of the TRR-registors is usually done at the factory before supplying the part.
Nr.
TRR bits
19-15
14-10
9-5
4-0
NOTE
0
Subregister
TRIMC
TRIMA
TRIMBV
TRIMBTC 1)
1
default
0
Notes:
1)
writing into TRR register is done as usual with the MSB first
subregister TRIMC
change of current source output with TRIMC bits
Nr.
trimc0
dI/Io
Notes
trimcs
trimc3
trimc2
trimc1
%
0
1),2)
1
0
1
-1*2.3
1),2)
2
0
1
0
-2*2.3
1),2)
..
14
0
1
0
–14*2.3
1),2)
15
0
1
–15*2.3
1),2)
16
1
0
16*2.3
1),2)
17
1
0
1
15*2.3
18
1
0
1
0
14*2.3
1),2)
..
30
1
0
2*2.3
1),2)
31
1
1*2.3
Notes:
1)
Io is the current in A at TRIMC = 00000
2)
The output current of the internal current source can be controlled in a wide range via the bit setting in CRG. In some applications it may be
necessary to trim the current in the rang of +/- 30% for an optimum result of the external temperature measurement. This trimming is achieved
with writing into subregister TRIMC of the TRR register. The trimming is done in % for all ranges selected in CRG register.
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