This is a setpoint controller circuit using The AD596/AD597. The thermocouple voltage is amplified, compared to an external setpoint voltage, and cold junction compensated. The device temperature can be monitored if the temperature to be controlled is within the operating range (–55°C to +125°C) of the device. Here is the schematic diagram of the circuit:
Setpoint Voltage of AD597 is °C × 10.1mV/°C – 9.1mV and Setpoint Voltage of AD596 is °C × 9.6mV/°C + 42mV. The setpoint pin of the AD596/AD597 has input impedance of about 50k. This resistance has temperature coefficient of ±15ppm/°C. This device has an additional ±1°C degradation of temperature stability over the +25°C to +100°C ambient temperature range due to 100ppm/°C 5k pot.
To increase system reliability and provide noise immunity, this device use Switching hysteresis. to enhanced system reliability, mechanical component wear is reduced by reducing the frequency of on-off cycling. It can be done by adding a single external resistor between Pins 7 and 3 of the AD596/AD597. The hysteresis is determined by following equation:
Rhyst=(Vout/200nA)*(1/°Chyst)
The alarm transistor will be ON regardless of whether there is an open circuit or not because the AD596/AD597 output is saturated at all times. for proper operationof the rest of the circuit, -ALM must be tied to a voltage below (+Vs – 4V) [Circuit's schematic diagram source: analog.com]
Possibly Related Articles:
- Temperature Controller for Crystal Oven
The temperature of a quartz crystal for oscillator should to be kept constant to operate at very stable frequency. This oven temperature controller is suitable for such purpose. Here is... - 230VAC Temperature Fan Control
This is a 230VAC Temperature Fan Control circuit. This circuit is used for 230Vac operation. The R9 can be changed to 15K 2W, if the AC operation is 115V. This... - IR-Linked Temperature Sensor
This is a circuit that transmits temperature data over an IR link and it allows the isolation of temperature sensor. It is a good solution of obtaining temperature readings from... - Temperature Measurement (Sensing) and Monitoring
Temperature measurement (sensing) and monitoring will be economical and straightforward if we apply the input of TC9400 V/F converter with a voltage from output of a probe, such as shown... - AD586/597 Temperature Transducer (Sensor)
This is a stand alone temperature transducer/sensor circuit. This device uses The AD596/AD597, employing its internal junction compensation temperature sensor inside. This device can be used as temperature sensor by...
| 
