Lake Shore 340

The Lake Shore 340 is a precision temperature controller engineered for cryogenic and scientific applications requiring accurate measurement and control down to 100 mK. It delivers independent dual PID control loops with the primary loop capable of supplying up to 100 W of variable DC power. The instrument accommodates multiple sensor types - silicon diodes, platinum RTDs, and NTC resistors - with optional expansion to thermocouple and capacitance inputs, scaling to ten total sensor channels.

Technical Specifications Temperature Performance

Measurement range: Down to 100 mK with appropriate NTC sensors

Resolution: As low as 0.1 mK at 4.2 K

24-bit ADC with low-noise circuit design Sensor Inputs

Two standard configurable inputs (diode/RTD)

Expandable to ten inputs with optional cards

Eight-channel scanner card for silicon diodes, PTC, and NTC RTD sensors

Thermocouple and capacitance sensor support via optional input cards

Selectable sensor excitation and input gain from front panel

Autoranging for NTC resistors to minimize self-heating

Automatic current reversal with rounded square wave excitation for NTC sensors to eliminate thermal EMF Control Loops

Two independent PID control loops with wide tuning parameters

Loop 1: Variable DC current source, up to 100 W maximum power

Loop 1 heater output protection: Setpoint temperature limit, current range limit, internal diagnostics, output fuse

Loop 2: Voltage output connectable directly to external power supply

High-resolution DAC for smooth control generation

Autotuning feature available Heater Power at Typical Resistances

10 Ω: 40 W (2 A), 10 W (1 A), 2.5 W (0.5 A), 625 mW (0.25 A)

25 Ω: 100 W (2 A), 25 W (1 A), 6.25 W (0.5 A), 1.56 W (0.25 A)

50 Ω: 50 W (2 A), 50 W (1 A), 12.5 W (0.5 A), 3.12 W (0.25 A) Temperature Response Curves

Standard curves included for silicon diodes, platinum RTDs, and thermocouboards

Supports up to twenty 200-point CalCurves™ for Lake Shore calibrated or user-defined sensors

CalCurves™ loadable via computer interface, front panel, or field-installable data card

Built-in SoftCal™ algorithm for silicon diode curve generation

Key Features

Dual independent control loops for simultaneous heating and external loop management

Flexible sensor ecosystem with optional expansion cards

Front-panel control of excitation parameters and input gain

Autotuning reduces manual PID optimization

Multiple heater power ranges accommodate diverse load requirements

Typical Applications

Dilution refrigerator operation and temperature stabilization

Cryogenic material characterization and testing

Superconductivity research and device cooling

Low-temperature physics experiments requiring multipoint monitoring

Compatibility & Integration The 340 accepts Lake Shore calibrated sensors and user-defined calibration curves. Integration paths include direct computer interface for CalCurve loading and front-panel data card installation for field calibration updates.