Analog Temperature Sensor - AD592 Analog Temperature Sensor - AD592 - - PowerPoint PPT Presentation

Analog Temperature Sensor - AD592 Analog Temperature Sensor - AD592

Continuous signal (µA) proportional to

temperature.

1 µA ~ 1 K, so 293 µA ~ 293 K (20 C) Current source

The digital DS1620 contains analog

components.

Transducer Response Transducer Response

Low 5 Rctime 5, 0, rct Voltage at P5 rises from 0 V to ~1.4 V. Temp (K) = Constant / rct Temp , Current Charge Time Automatic calibration

0.22 F 5 V P5 0 V 100

Resistance & Resistivity, ρ ρ ρ ρ Resistance & Resistivity, ρ ρ ρ ρ

Resistance is the opposition to current flow. In a conductor, R = ρ

ρ ρ ρ x Length / Area

Different materials have different resistivities. Generally, ρ

ρ ρ ρ is temperature dependent.

Temp , ρ

ρ ρ ρ

Conductance,G & Resistance,R Conductance,G & Resistance,R

V=RI and I=GV, so G=1/R Conductance = reciprocal of resistance. Units of G = Siemens (S) Conductance is a measure of how

easily current can flow.

Series Resistors, R1 & R2 Series Resistors, R1 & R2

Req R1 R 2 Geq (G1 G2 )

1 1 1

= + = +

− − −

Resistors R1 & R2 in Parallel Resistors R1 & R2 in Parallel

Req (R1 R 2 ) Geq G1 G2

1 1 1

= + = +

− − −