Datasheet
Table Of Contents
- Features
- Applications
- Description
- Absolute Maximum Ratings
- Operating Ratings
- Electrical Characteristics
- I2C Interface
- Timing Characteristics
- Timing Diagram
- Typical Performance Characteristics
- Function Description
- Application Information
- Revision History
I2C INTERFACE
AND
CONTROL
REGISTERS
RE
VREF
VDD
AGND
CE
WE
VOUT
C1
SCL
TEMP
SENSOR
VREF
DIVIDER
C2
SDA
R
Load
VARIABLE
BIAS
LMP91000
MENB
DGND
A1
+
-
TIA
+
-
R
TIA
VE-
VE+
NC
2-wire
Sensor
such as
Oxygen
LMP91000
SNAS506H –JANUARY 2011–REVISED MARCH 2013
www.ti.com
Figure 30. 2-Lead Galvanic Cell Ground Referred
2-lead Galvanic Cell In Potentiostat Configuration
When the LMP91000 is interfaced to a galvanic cell (for instance to an Oxygen gas sensor) referred to a
reference, the Counter and the Reference pin of the LMP91000 are shorted together and connected to negative
electrode of the galvanic cell. The positive electrode of the galvanic cell is then connected to the Working pin of
the LMP91000.
The LMP91000 is then configured in 3-lead amperometric cell mode (as for amperometric cell). In this
configuration the Control Amplifier (A1) is ON and provides the internal zero voltage. The transimpedance
amplifier (TIA) is also ON, it converts the current generated by the gas sensor in a voltage, according to the
transimpedance gain:
Gain= R
TIA
If different gains are required, an external resistor can be connected between the pins C1 and C2. In this case
the internal feedback resistor should be programmed to “external”.
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