LMP91000SDE National Semiconductor, LMP91000SDE Datasheet - Page 18

• Manufacturer Part Number: LMP91000SDE
• Description: AFE, SENSOR, 14LLP
• Manufacturer: National Semiconductor

Specifications of LMP91000SDE

• Brief Features: Programmable Cell Bias Voltage, Low Bias Voltage Drift, I2C Compatible Digital Interface
• Supply Voltage Range: 2.7V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LLP
• Ic Function: Programmable Analogue Front End (AFE)
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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2-lead Galvanic Cell In Potentiostat Configuration
When the LMP91000 is interfaced to a galvanic cell (for in-
stance 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 con-
nected 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
FIGURE 5. 2-Lead Galvanic Cell Ground Referred
18
Control Amplifier (A1) is ON and provides the internal zero
voltage. The transimpedance amplifier (TIA) is also ON and
it is configured as an inverting amplifier, the gain is set ac-
cording the following formula:
Gain= -(R
If different gains are required, an external resistor can be
connected between the pins C1 and C2. In this case the in-
ternal feedback resistor should be programmed to “external”.
TIA
/R
Load
)
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