LMP90080/LMP90079/
LMP90078/LMP90077
August 30, 2011
Sensor AFE System: Multi-Channel, Low-Power 16-Bit
Sensor AFE with True Continuous Background Calibration
1.0 General Description
The LMP90080/LMP90079/LMP90078/LMP90077 are highly
integrated, multi-channel, low-power 16-bit Sensor AFEs.
The devices feature a precision, 16-bit Sigma Delta Analog-
to-Digital Converter (ADC) with a low-noise programmable
gain amplifier and a fully differential high impedance analog
input multiplexer. A true continuous background calibration
feature allows calibration at all gains and output data rates
without interrupting the signal path. The background calibra-
tion feature essentially eliminates gain and offset errors
across temperature and time, providing measurement accu-
racy without sacrificing speed and power consumption.
Another feature of the LMP90080/LMP90079/LMP90078/
LMP90077 is continuous background sensor diagnostics, al-
lowing the detection of open and short circuit conditions and
out-of-range signals, without requiring user intervention, re-
sulting in enhanced system reliability.
Two sets of independent external reference voltage pins allow
multiple ratiometric measurements. In addition, two matched
programmable
current
sources
are
available
in
the
LMP90080/LMP90078 to excite external sensors such as re-
sistive temperature detectors and bridge sensors. Further-
more, seven GPIO pins are provided for interfacing to external
LEDs and switches to simplify control across an isolation bar-
rier.
Collectively, these features make the LMP90080/LMP90079/
LMP90078/LMP90077 complete analog front-ends for low-
power, precision sensor applications such as temperature,
pressure, strain gauge, and industrial process control. The
LMP90080/LMP90079/LMP90078/LMP90077 are guaran-
teed over the extended temperature range of -40°C to +125°
C and are available in a 28-pin TSSOP package.
2.0 Features
■ 16-Bit Low-Power Sigma Delta ADC
■ True Continuous Background Calibration at all gains
■ In-Place System Calibration using Expected Value
programming
■ Low-Noise programmable gain (1x - 128x)
■ Continuous background open/short and out of range
sensor diagnostics
■ 8 output data rates (ODR) with single-cycle settling
■ 2 matched excitation current sources from 100 A to
1000 A (LMP90080/LMP90078)
■ 4-DIFF / 7-SE inputs (LMP90080/LMP90079)
■ 2-DIFF / 4-SE inputs (LMP90078/LMP90077)
■ 7 General Purpose Input/Output pins
■ Chopper-stabilized buffer for low offset
■ SPI 4/3-wire with CRC data link error detection
■ 50 Hz to 60 Hz line rejection at ODR ≤13.42 SPS
■ Independent gain and ODR selection per channel
■ Supported by Webench Sensor AFE Designer
■ Automatic Channel Sequencer
3.0 Key Specifications
■ENOB/NFR
Up to 16/16 bits
■Offset Error (typ)
8.4 nV
■Gain Error (typ)
7 ppm
■Total Noise
< 10 V-rms
■Integral Non-Linearity (INL max)
±1LSB
■Output Data Rates (ODR)
1.6775 SPS - 214.65 SPS
■Analog Voltage, VA
+2.85V to +5.5V
■Operating Temp Range
-40°C to 125°C
■Package
28-Pin TSSOP
4.0 Applications
■ Temperature and Pressure Transmitters
■ Strain Gauge Interface
■ Industrial Process Control
5.0 Typical Application
30169774
TRI-STATE is a registered trademark of National Semiconductor Corporation.
2011 National Semiconductor Corporation
301697
www.national.com
LMP90080/LMP90079/LMP90078/LMP90077
Sensor
AFE
System:
Multi-Channel,
Low-Power
16-
Bit
Sensor
AFE
with
True
Continuous
Background
Calibration