Omega CYD200 Series, User Manual

Omega Model CYD201/202 User’s Manual 

2-10 Installation 

Sensor Mounting (Continued) 

CAUTION:

 Omega will not warranty replace any device damaged by user-

designed clamps or solder mounting. 

For semi-permanent mountings, use Stycast epoxy instead of Apiezon

®

 N 

Grease. 

NOTE:

 Do not apply Stycast epoxy over the CY7-SD package--sensor 

stress may shift the readings. In all cases, periodically inspect the sensor 

mounting to verify good thermal contact to the mounting surface is 

maintained. 

2.4.4 

Current Source Dependence 

This paragraph addresses the effects of current source accuracy on 

temperature measurement accuracy. Although the Model CYD201 has an 

accurate internal current source, it is important to understand the 

relationship between current variation and measurement accuracy. 

Diode sensors possess a non-linear forward current-voltage characteristic. 

Consequently, the forward voltage variation with changing current for diodes 

is smaller than for resistance temperature sensors, which have linear 

current-voltage characteristics. 

Below 30 K, the sensitivity (dV/dT) of Omega Engineering diode 

temperature sensors increases by an order of magnitude over sensitivities 

at higher temperatures. The slope (dV/dI) of the I-V curves stays relatively 

constant. Both characteristics reduce even further the effect of any change 

in forward bias current on temperature measurement accuracy. Refer to 

Tables 2-1 and 2-2. 

Table 2-1. Effect of Current Variation 

on Diode Temperature Measurement Accuracy 

T (K) 

∆∆∆∆

I, µA*  Acc. (%)* 

Range (µA)* 

Error (K) 

300 

0.5 

0.05 

0.005 

5 

0.5 

0.05 

9.5 to 10.5 

9.95 to 10.05 

9.995 to 10.005 

1 

0.1 

0.01 

150 

1 

0.1 

0.01 

0.005 

10 

1 

0.1 

0.05 

9 to 11 

9.9 to 10.1 

9.99 to 10.01 

9.995 to 10.005 

1 

0.1 

0.01 

0.005 

50 

3 

0.3 

0.03 

0.005 

30 

3 

0.3 

0.05 

7 to 13 

9.7 to 10.3 

9.97 to 10.03 

9.995 to 10.005 

1 

0.1 

0.01 

0.005 

* With current source (I

≈

10 µA).