Lake Shore Model 331 Temperature Controller User’s Manual
Specifications (Continued)
Control
Control loops
Two on 331S, one on 331E
Control type
Closed loop digital PID with manual heater output, or open loop
Tuning
Autotune (one loop at a time), PID, PID zones
Control stability
Sensor dependent – to 2× measurement resolution
(in an ideal thermal system)
PID control parameters
Proportional (gain)
0 to 1000 with 0.1 setting resolution
Integral (reset)
1 to 1000 (1000/s) with 0.1 setting resolution
Derivative (rate)
1 to 200% with 1% resolution
Manual output
0 to 100% with 0.01% setting resolution
Zone control
10 temperature zones with P, I, D, manual heater out, and heater range
Setpoint ramping
0.1 K/min to 100 K/min
Safety limits
Curve temperature, power up heater off, short circuit protection
Table 1-5. Heater Output
Loop 1
Loop 2
Heater output type
Variable DC current source
Variable DC voltage source
Heater output D/A resolution
18-bit
16-bit
Max heater power
50 W
1 W
Max heater output current
1 A
0.1 A
Heater output compliance
50 V
10 V
Heater output ranges
3 decade steps in power
1
Heater load type
Resistive
Resistive
Heater load range
10
Ω
to 100
Ω
recommended
100
Ω
minimum
Heater load for max power
50
Ω
100
Ω
Heater noise (<1 kHz) RMS
50 µV + 0.01% of output voltage
<0.3 mV
Isolation
Optical isolation between output and
other circuits
None
Heater connector
Dual banana
Detachable terminal block
Table 1-6. Loop 1 Full Scale Heater Power at Typical Resistance
Heater Resistance
Heater Range
Heater Power
10
Ω
Low
Med
High
100 mW
1 W
10 W
25
Ω
Low
Med
High
250 mW
2.5 W
25 W
50
Ω
Low
Med
High
500 mW
5 W
50 W
Introduction
1-7
