MLX90308CCC

Programmable Sensor Interface

MLX90308CCC Programmable Sensor Interface

Page 24

Rev 2.2

23/Oct/01

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IO1

IO2

TSTB

FLT

OFC

VBN

VBP

TMP

COMS

GND

CMN

CMO

VMO

VDD1

FET

VDD

G

S

D

External FET

for Regulation

Pressure

Sensor

Oil

Pressure

(psi)

Communication

s

GND

Signal Out

V

+

Programmable Oil Pressure Gauge

This application example illustrates a fundamental

application of the MLX90308 and a bridge type

pressure sensor element. In this application, the

MLX90308 uses an external FET as a pass transistor to

regulate the voltage to the sensor and the analog portion

of the IC. This is known as Absolute Voltage Mode, where

voltage to the sensor and analog circuit is regulated independent

of the supply voltage. The MLX90308 can be operated in Ratiometric

Voltage Mode, in which the output (VMO) is tied to an A/D converter

sharing the same supply and ground reference. A third wiring option is

Current Mode, which allows the user a 4 to 20 milliampere current range to use as a

2-wire analog sensor.

Communications

Signal Out

GND

V+

Figure 10. Application Example

Figure 10a. Programmable Oil Pressure Gauge

Figure 10b. Programmable Oil Pressure Gauge Electrical Connections