AD74115 datasheet(8/103 Pages) AD

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Data Sheet

AD74115

SPECIFICATIONS

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Rev. 0 | 8 of 103

3-WIRE RTD MEASUREMENT

AVDD = +6 V to +28.8 V, AVSS = −2.5 V to −18 V, AGND = DGND = 0 V, REFIN = +2.5 V (ideal), DVCC = +2.7 V to +5.5 V, AVCC = +4.5

V to +5.5 V, and all specifications are at TA = −40°C to +105°C, unless otherwise noted. RSENSE = 100 Ω (ideal) and CLOAD = 4.7 nF per the

recommended configuration.

Table 7. 3-Wire RTD Measurement

Parameter

Min

Typ

Max

Unit

Test Conditions/Comments

RESISTANCE MEASUREMENT

Input Range

0.001

kΩ

Programmable Excitation Current

250

µA

The voltage generated across the (reference resistor (RREF) +

the RTD resistor (RRTD)) must be less than the AVCC voltage

(VAVCC)

500

µA

750

µA

Current Matching

Excitation Current Matching

−0.5

+0.5

For 500 µA, 750 µA, and 1 mA

Current Matching Drift

ppm/˚C

Open-Circuit Detect Voltage

Excitation current and resistor combinations generating a

voltage greater than this are treated as open-circuit

SENSEH

4.0

SENSE_EXT1

2.7

ACCURACY1

Measurement Range

1 Ω to 40 Ω

±0.036,

±0.023

±% of the measured value plus ± the fixed error, suitable for

Pt10, Cu10, or similar, 1 mA excitation current and 104.16 mV

ADC range

10 Ω to 400 Ω

±0.037,

±0.037

±% of the measured value, suitable for Pt100 or similar, 1 mA

excitation current, and 0.625 V ADC range

100 Ω to 4 kΩ

±0.084,

±0.358

±% of the measured value, suitable for Pt1000, and 500 μA

excitation current, and 0 V to 12 V ADC range

1 Guaranteed by design and characterization.

4-WIRE RTD MEASUREMENT

AVDD = +6 V to +28.8 V, AVSS = −2.5 V to −18 V, AGND = DGND = 0 V, REFIN = +2.5 V (ideal), DVCC = +2.7 V to +5.5 V, AVCC = +4.5

V to +5.5 V, and all specifications are at TA = −40°C to +105°C, unless otherwise noted. RSENSE = 100 Ω (ideal) and CLOAD = 4.7 nF per the

recommended configuration.

Table 8. 4-Wire RTD Measurement

Parameter

Min

Typ

Max

Unit

Test Conditions/Comments

RESISTANCE MEASUREMENT

Input Range

0.001

kΩ

Programmable Excitation Current

250

µA

The voltage generated across (RREF + RRTD) must be less than

VAVCC

500

µA

750

µA

SENSEH Open-Circuit Detect Voltage

4.0

Excitation current and resistor combinations generating a

voltage greater than this are treated as open-circuit

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