LMP91000_14 Datasheet, PDF (1/31 Pages) Texas Instruments – Sensor AFE System

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LMP91000
SNAS506I – JANUARY 2011 – REVISED DECEMBER 2014
LMP91000 Sensor AFE System: Configurable AFE Potentiostat for Low-Power Chemical-
Sensing Applications
1 Features
•1 Typical Values, T_A = 25°C
• Supply Voltage 2.7 V to 5.25 V
• Supply Current (Average Over Time) <10 µA
• Cell Conditioning Current Up to 10 mA
• Reference Electrode Bias Current (85°C) 900pA
(max)
• Output Drive Current 750 µA
• Complete Potentiostat Circuit-to-Interface to Most
Chemical Cells
• Programmable Cell Bias Voltage
• Low-Bias Voltage Drift
• Programmable TIA gain 2.75 kΩ to 350 kΩ
• Sink and Source Capability
• I²C Compatible Digital Interface
• Ambient Operating Temperature –40°C to 85°C
• Package 14-Pin WSON
• Supported by WEBENCH^® Sensor AFE Designer
2 Applications
• Chemical Species Identification
• Amperometric Applications
• Electrochemical Blood Glucose Meter
3 Description
The LMP91000 is a programmable analog front-end
(AFE) for use in micro-power electrochemical sensing
applications. It provides a complete signal path
solution between a sensor and a microcontroller that
generates an output voltage proportional to the cell
current. The LMP91000’s programmability enables it
to support multiple electrochemical sensors such as
3-lead toxic gas sensors and 2-lead galvanic cell
sensors with a single design as opposed to the
multiple discrete solutions. The LMP91000 supports
gas sensitivities over a range of 0.5 nA/ppm to 9500
nA/ppm. It also allows for an easy conversion of
current ranges from 5 µA to 750 µA full scale.
The LMP91000’s adjustable cell bias and
transimpedance amplifier (TIA) gain are
programmable through the I²C interface. The I²C
interface can also be used for sensor diagnostics. An
integrated temperature sensor can be read by the
user through the VOUT pin and used to provide
additional signal correction in the µC or monitored to
verify temperature conditions at the sensor.
The LMP91000 is optimized for micro-power
applications and operates over a voltage range of 2.7
to 5.25 V. The total current consumption can be less
than 10 μA. Further power savings are possible by
switching off the TIA amplifier and shorting the
reference electrode to the working electrode with an
internal switch.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMP91000
WSON (14)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
3-Lead
Electrochemical
Cell
CE
Simplified Application Schematic
LMP91000
+
A1
-
VREF
VDD
VARIABLE
BIAS
VREF
DIVIDER
I2C INTERFACE
AND
CONTROL
REGISTERS
SCL
SDA
MENB
CONTROLLER
CE
RE
WE
RE
WE
RLoad
+
TIA
-
RTIA
C1
C2
TEMP
SENSOR
DGND
VOUT
AGND
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.