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REV1A

Description

The XR18910 is a unique sensor interface integrated circuit with an

onboard 8:1 multiplexer, offset correction Digital-to-Analog Converter

(DAC), instrumentation amplifier and voltage reference. The XR18910

is designed to integrate multiple bridge sensors with a Microcontroller

(MCU) or Field-Programmable Gate Array (FPGA).

The integrated offset correction DAC provides digital calibration of the

variable and in many cases substantial offset voltage generated by the

interface. The serial interface also provides the user with easy controls

to the XR18910’s many functions such as input and gain selection.

A linear regulator (LDO) provides a regulated voltage to power the input

bridge sensors and is selectable, between 3V and 2.65V. The LDO

current can be sensed and a proportional voltage present at the output

of the IC for monitoring the LDO current.

The XR18910 offers 8 fixed gain settings (from 2V/V to 760V/V), each

It also offers less than 3mV maximum input offset voltage, 100pA

maximum input bias current, and 100pA maximum input offset current.

The XR18910 is designed to operate from 2.7V to 5V supplies, specified

over the industrial temperature range of -40°C to 85°C and is offered in

a space saving 3.5mm x 3.5mm QFN package. It consumes less than

559μA supply current and offers a sleep mode for added power savings.

The XR18910 is well suited for industrial and consumer applications

using bridge sensors.

Typical Application

FEATURES

■

■

Integrated features for interfacing multiple

bridge sensors with an MCU or FPGA

Instrumentation amplifier

LDO

(±560mV offset correction range)

■

■

Eight selectable voltage gains from 2V/V to

760V/V with only ±0.5% gain error

■

■

3mV maximum input offset voltage

■

■

100pA maximum input bias current

■

■

559μA maximum supply current

■

■

2.7V to 5V analog supply voltage range

■

■

1.8V to 5V digital supply voltage range

■

■

-40°C to 85°C temperature range

■

■

3.5mm x 3.5mm QFN-24 package

APPLICATIONS

■

■

Bridge sensor interface

■

■

Pressure and temperature sensors

■

■

Strain gauge amplifier

■

■

Industrial process controls

■

■

Weigh scales

Figure 1. Typical Application

Figure 2. 0.1Hz to 10Hz RTI Voltage Noise

BRIDGE 8

BRIDGE 1

ADC

µC

OUT

SDA

SCL

IN1+

IN1-

IN8+

IN8-

BRDG

8:1

MUX

LDO

INA /

PGA

CONTROL

PGA

±560mV

OFFSET TRIM

10-BIT

DAC

0.1F

6.8F

+

10k

VCC

VDD

0.1F

6.8F

+

0.1F

4.7k

4.7k

AGND

DGND

10nF

XR18910

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

0

2

4

6

8

10

Time (seconds)

XR18910

8:1 Sensor Interface Analog Front End