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.
