AD594 Analog Devices, Inc., AD594 Datasheet
AD594
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AD594 Summary of contents
Page 1
... The alarm output has a flexible format which includes TTL drive capability. The AD594/AD595 can be powered from a single ended supply (including +5 V) and by including a negative supply, tempera- tures below 0 C can be measured. To minimize self-heating, an unloaded AD594/AD595 will typically operate with a total sup- ply current 160 A, but is also capable of delivering in excess load ...
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... AD594AQ NOTES 1 Calibrated for minimum error at +25 C using a thermocouple sensitivity of 51 Since a J type thermocouple deviates from this straight line approximation, the AD594 will normally read 3.1 mV when the measuring junction The AD595 will similarly read 2 Defined as the slope of the line connecting the AD594/AD595 errors measured and 50 C ambient temperature. ...
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... SINGLE AND DUAL SUPPLY CONNECTIONS The AD594/AD595 is a completely self-contained thermocouple conditioner. Using a single +5 V supply the interconnections shown in Figure 1 will provide a direct output from a type J thermocouple (AD594) or type K thermocouple (AD595) mea- suring from +300 C. 10mV/ C Any convenient supply voltage from + +30 V may be ...
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... THERMOCOUPLE CONNECTIONS The isothermal terminating connections of a pair of thermo- couple wires forms an effective reference junction. This junction must be kept at the same temperature as the AD594/AD595 for the internal cold junction compensation to be effective. A method that provides for thermal equilibrium is the printed circuit board connection layout illustrated in Figure 3. ...
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... Both the AD594 and AD595 can be configured to condition the output of a type E (chromel-constantan) thermocouple. Tem- perature characteristics of type E thermocouples differ less from type J, than from type K, therefore the AD594 is preferred for recalibration. While maintaining the device at a constant temperature follow the recalibration steps given here. First, measure the device ...
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... With an AD594 about 200 nA into the +T terminal provides hysteresis. When using a single 5 V supply with an AD594 resistor from V +T will supply the 200 nA of current when the output is forced high (about 4 V). To widen the hysteresis band decrease the resistance connected from ...
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... ALARM CIRCUIT In all applications of the AD594/AD595 the –ALM connection, Pin 13, should be constrained so that it is not more positive than (V+) – This can be most easily achieved by connect- ing Pin 13 to either common at Pin 4 or V– at Pin 7. For most applications that use the alarm signal, Pin 13 will be grounded and the signal will be taken from +ALM on Pin 12 ...
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... Temperature for Ice Point Reference T2 The temperature sensitivity of silicon integrated circuit transis- tors is quite predictable and repeatable. This sensitivity is ICE POINT exploited in the AD594/AD595 to produce a temperature re- REFERENCE lated voltage to compensate the reference of “cold” junction of a thermocouple as shown in Figure 16. T1 Figure 16. Connecting Isothermal Junctions Since the compensation is at the reference junction temperature often convenient to form the reference “ ...