The Stanford Research SIM925 is an octal 4-wire multiplexer module that routes one of eight input signals to a common output while preserving signal integrity in low-level measurement applications. Operating as a standalone unit or within the SIM900 Mainframe ecosystem, the SIM925 delivers break-before-make switching with a 50 ms maximum response time and a clock-stopping architecture that suppresses digital noise. Its 4-wire configuration supports Kelvin-lead measurements across eight channels plus one bypass channel, making it ideal for precision sensing and automated signal recovery tasks.
Technical Specifications
• Input channels: 8 plus 1 bypass
• Switching order: Break-before-make (default); make-before-break (remote interface only)
• Switching speed: 50 ms maximum
• Bandwidth: 1 MHz (typical)
• Series resistance: 2.0 Ω maximum
• Bias current: 5 pA typical
• Isolation resistance: >10 GΩ typical
• Maximum switching capacity: 10 mA @ 10 VDC
• Input capacitance (selected channel, any 2 leads or ground): <60 pF
• Input capacitance (selected to unselected channel, any 2 leads): <25 pF
• Input capacitance (unselected channels): <25 pF
• Thermal EMF: <10 µV typical
• Module weight: 1.5 lbs
– Key Features
• 4-wire signal routing with selectable buffering on sense leads
• Operates standalone with ±15 V and +5 V DC power, or powered by SIM900 Mainframe
• DB-37 female connector (inputs); DB-9 connectors for bypass and common output
• Rear-panel bypass feature enables module cascading and daisy-chaining
• Clock-stopping architecture minimizes noise in sensitive analog applications
• Buffer switchable to configure as simple relay-based 4-pole/8-throw switch
– Typical Applications
• Temperature sensing via SIM921 AC Resistance Bridge, SIM922A Diode Monitor, or SIM923A RTD Monitor
• Multi-source signal routing to lock-in amplifiers for automated recovery
• Precision measurement systems requiring low thermal EMF and high isolation
– Compatibility & Integration
The SIM925 integrates within the modular SIM platform, sharing mainframe power, clock synchronization, and communications with other SIM modules. Multiple units cascade via rear-panel bypass connections for expanded channel capacity.
