Output

O P E R A T I O N

Introduction to the LDT-5525 Front Panel

C H A P T E R 2

Appendix C contains information on sensor calibration constants for AD590 and LM335 sensors. Since these devices are used over their linear range, the constants C1 and C2 are used in this case to determine a linear approximation of the temperature, rather than the Steinhart-Hart non-linear approximation which applies for thermistors. The appropriate algorithms are automatically implemented whenever the sensor type is selected via the back panel SENSOR SELECT switch. However, C1 and C2 must be changed by the user.

The OUTPUT section contains the ON switch and indicator. The ON indicator is lit whenever the output is on. Pressing the ON switch will toggle the TEC current output on or off.

Conditions Which Will Automatically Shut Off the OUTPUT

1Temperature Limit

2External (Temp Limit) Safety Switch is closed (see Section 2.6.3)

3Booster Changed (While Output On), (see Section 2.6.4)

4Sensor Open (While Output On)

5TEC Module Open (While Output On)

6SENSOR SELECT Switch Moved (While Output On)

Control Mode

The MODE switch is used to select the control mode. Repeatedly pressing the MODE switch cycles through the current (I TE), sensor reference (R), or temperature (T) control modes. The LED indicators show the selected mode. Changing the control mode forces the output off.

Error Indicators

The ERROR indicators become lit when the corresponding conditions occur. The SENSOR OPEN light comes on whenever the sensor connections are open. The TE OPEN indicator becomes lit whenever an open circuit (or a high impedance condition) occurs on the TE module output when the output is on. When a TE OPEN condition occurs, the output will be shut off and the indicator will remain on until the problem is resolved and the output is turned on again.

The T LIMIT light will blink at 1 Hz whenever the temperature limit is reached. The I LIMIT light will blink at 1 Hz whenever the I TE current limit is reached.

06_07

LDT-5525