LMP91200_16 Datasheet, PDF (1/24 Pages) Texas Instruments – Configurable AFE for Low-Power Chemical-Sensing Applications

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LMP91200
SNAS571E – JANUARY 2012 – REVISED FEBRUARY 2016
LMP91200 Configurable AFE for Low-Power Chemical-Sensing Applications
1 Features
•1 Active Guarding
• Key Specifications
Unless otherwise noted, typical values at
T_A = 25°C, V_S = (VDD-GND) = 3.3 V
– pH Buffer Input Bias Current (0 < V_INP < 3.3 V)
– Maximum at 25°C: ±125 fA
– Maximum at 85°C: ±445 fA
– pH Buffer Input Bias Current
(–500 mV < V_INP– V_CM < 500 mV),
V_S = (VDD – GND) = 0 V
– Maximum at 25°C: ±600 fA
– Maximum at 85°C: ±6.5 pA
– pH Buffer Input Offset Voltage: ±200 µV
– pH Buffer Input Offset Voltage Drift: ±2.5
μV/°C
– Supply Current: 50 μA
– Supply Voltage: 1.8 V to 5.5 V
– Operating Temperature Range: –40°C to
125°C
– Package: 16-Pin TSSOP
2 Applications
• pH Sensor Platforms
3 Description
The LMP91200 device is a sensor AFE for use in
low-power, analytical-sensing applications. The
LMP91200 is designed for 2-electrode sensors. This
device provides all of the functionality needed to
detect changes based on a delta voltage at the
sensor. Optimized for low-power applications, the
LMP91200 works over a voltage range of 1.8 V to 5.5
V. With its extremely low input bias current it is
optimized for use with pH sensors. Also, in absence
of supply voltage the very low input bias current
reduces degradation of the pH probe when
connected to the LMP91200. Two guard pins provide
support for high parasitic impedance wiring.
Depending on the configuration, total current
consumption for the device is 50 µA while measuring
pH. Available in a 16-pin TSSOP package, the
LMP91200 operates from –40°C to +125°C.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMP91200
TSSOP (16)
5.00 mm × 4.40 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application
VDD
NC
LMP91200
NC
GUARD1
INP
GUARD2
± _pH
BUFFER
+
VDD
GND
GND
VOUT
VOCM
MCU
ADC
VREF
pH Electrode
VCM
VCM
BUFFER
VCMHI
GND
GND
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.