Datasheet

LMP91200
SNAS571C –JANUARY 2012–REVISED MARCH 2013 www.ti.com
Vos=(VOUT_R
REF0
-VOUT_R
REF1
)/5
where
• VOUT_R
REF0
is the amplified voltage across the R
REF
at VOUT pin (ground referred), when the LMP91200 is
configured according to Table 5
• VOUT_R
REF 1
is the amplified voltage across the R
REF
at VOUT pin (ground referred), when the LMP91200 is
configured according to Table 6 (10)
I_true=(2*VOUT_R
REF1
-VOUT_R
REF0
)/(10*R
REF
) (11)
Inserting Equation 9, Equation 10 and Equation 11 in Equation 8 the temperature is given by the following
equation:
Temp(°C) = (((VOUT_Pt
RES
/PGA_GAIN)-(VOUT_R
REF0
-VOUT_R
REF1
)/5)/((2*VOUT_R
REF1
-VOUT_R
REF0
)/(10*R
REF
))–
Pt
RES
_nominal) /alpha (12)
Table 5.
Bit Name Description
D15 MEAS_MODE 1 Temp measurement
D14 I_MUX 1 RCAL
01 200µA (Pt1000)
[D13:D12] I_VALUE
11 2 mA (Pt100)
D11 PGA 0 5 V/V
Leave these bits as they have been configured for the pH
[D10 :D8] VCM
measurement.
D7 VOCM 1 GND
D6 DIAG_EN 0 DIAGNOSTIC disabled
[D5 :D0] RESERVED RESERVED
Table 6.
Bit Name Description
D15 MEAS_MODE 1 Temp measurement
D14 I_MUX 1 RCAL
00 100µA (Pt1000)
[D13:D12] I_VALUE
10 1 mA (Pt100)
D11 PGA 1 10 V/V
Leave these bits as they have been configured for the pH
[D10 :D8] VCM
measurement.
D7 VOCM 1 GND
D6 DIAG_EN 0 DIAGNOSTIC disabled
[D5 :D0] RESERVED RESERVED
Table 7. Configuration register: 3-step measurement
Bit Name Description
D15 MEAS_MODE 1 Temp measurement
D14 I_MUX 0 RTD
00 100µA (Pt1000)
[D13:D12] I_VALUE
10 1 mA (Pt100)
D11 PGA 1 10 V/V
Leave these bits as they have been configured for the pH
[D10 :D8] VCM
measurement.
D7 VOCM 1 GND
D6 DIAG_EN 0 DIAGNOSTIC disabled
[D5 :D0] RESERVED RESERVED
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