AD594/AD595–SPECIFICATIONS

REV. C

–2–

Model

AD594A

AD594C

AD595A

AD595C

Min

Typ

Max

Min

Typ

Max

Min

Typ

Max

Min

Typ

Max

Units

ABSOLUTE MAXIMUM RATING

36

36

36

36

Volts

Common-Mode Input Voltage

Volts

Differential Input Voltage

Volts

Alarm Voltages

+ALM

Volts

–ALM

Volts

Operating Temperature Range

–55

+125

–55

+125

–55

+125

–55

+125

°C

Output Short Circuit to Common

Indefinite

Indefinite

Indefinite

Indefinite

TEMPERATURE MEASUREMENT

(Specified Temperature Range

0

°C to +50°C)

Calibration Error at +25

3

1

3

1

°C

Stability vs. Temperature

2

0.05

0.025

0.05

0.025

°C/°C

Gain Error

1.5

0.75

1.5

0.75

%

Nominal Transfer Function

10

10

10

10

mV/

°C

AMPLIFIER CHARACTERISTICS

Closed Loop Gain

3

193.4

193.4

247.3

247.3

Input Offset Voltage

(Temperature in

°C) ×

(Temperature in

°C) ×

(Temperature in

°C) ×

(Temperature in

°C) ×

51.70

µV/°C

51.70

µV/°C

40.44

µV/°C

40.44

µV/°C

µV

Input Bias Current

0.1

0.1

0.1

0.1

µA

Differential Input Range

–10

+50

–10

+50

–10

+50

mV

Common-Mode Range

Volts

Common-Mode Sensitivity – RTO

10

10

10

10

mV/V

Power Supply Sensitivity – RTO

10

10

10

10

mV/V

Output Voltage Range

Dual Supply

Volts

Single Supply

0

0

0

0

Volts

Usable Output Current

4

±5

±5

±5

±5mA

3 dB Bandwidth

15

15

15

15

kHz

ALARM CHARACTERISTICS

0.3

0.3

0.3

0.3

Volts

Leakage Current

1

1

1

1

µA max

Operating Voltage at – ALM

Volts

Short Circuit Current

20

20

20

20

mA

POWER REQUIREMENTS

Specified Performance

Volts

Operating

5

Volts

Quiescent Current (No Load)

160

300

160

300

160

300

160

300

µA

100

100

100

100

µA

PACKAGE OPTION

TO-116 (D-14)

AD594AD

AD594CD

AD595AD

AD595CD

Cerdip (Q-14)

AD594AQ

AD594CQ

AD595AQ

AD595CQ

NOTES

°C using a thermocouple sensitivity of 51.7 µV/°C. Since a J type thermocouple deviates from this straight line approximation, the AD594 will normally

read 3.1 mV when the measuring junction is at 0

°C. The AD595 will similarly read 2.7 mV at 0°C.

°C and 50°C ambient temperature.

Ω resistor at output voltages below 2.5 V.

Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications

are guaranteed, although only those shown in boldface are tested on all production units.

Specifications subject to change without notic

e.

unless otherwise noted)

INTERPRETING AD594/AD595 OUTPUT VOLTAGES

To achieve a temperature proportional output of 10 mV/

°C and

accurately compensate for the reference junction over the rated

operating range of the circuit, the AD594/AD595 is gain trimmed

to match the transfer characteristic of J and K type thermocouples

at 25

°C. For a type J output in this temperature range the TC is

51.70

µV/°C, while for a type K it is 40.44 µV/°C. The resulting

gain for the AD594 is 193.4 (10 mV/

°C divided by 51.7 µV/°C)

and for the AD595 is 247.3 (10 mV/

°C divided by 40.44 µV/°C).

In addition, an absolute accuracy trim induces an input offset to

the output amplifier characteristic of 16

µV for the AD594 and

11

µV for the AD595. This offset arises because the AD594/

AD595 is trimmed for a 250 mV output while applying a 25

°C

thermocouple input.

Because a thermocouple output voltage is nonlinear with respect

to temperature, and the AD594/AD595 linearly amplifies the

compensated signal, the following transfer functions should be

used to determine the actual output voltages:

AD594 output = (Type J Voltage + 16

µV) × 193.4

AD595 output = (Type K Voltage + 11

µV) × 247.3 or conversely:

Type J voltage = (AD594 output/193.4) – 16

µV

Type K voltage = (AD595 output/247.3) – 11

µV

Table I lists the ideal AD594/AD595 output voltages as a func-

tion of Celsius temperature for type J and K ANSI standard

thermocouples, with the package and reference junction at

25

°C. As is normally the case, these outputs are subject to cali-

bration, gain and temperature sensitivity errors. Output values

for intermediate temperatures can be interpolated, or calculated

using the output equations and ANSI thermocouple voltage

tables referred to zero degrees Celsius. Due to a slight variation