Agilent / Keysight 34925A 40/80 Channel Optically Isolated FET Multiplexer for 34980A

The Keysight 34925A is a high-density, optically isolated FET multiplexer module for the 34980A multifunction switch/measure unit. It delivers 40 or 80 channels of precision signal routing with fast scanning capability and solid-state relay longevity. Engineered for automated test systems requiring low-distortion switching, the module supports mixed 2-wire and 4-wire configurations on a single card, enabling flexible channel allocation for diverse measurement topologies.

Technical Specifications

• 80 channels (1-wire configuration)


• 40 channels (2-wire configuration)


• 20 channels (4-wire configuration)


• Mixed 2-wire and 4-wire operation supported on the same module


• 1:N closure topology - one channel per bank closes at a time Electrical Performance


• Peak switch voltage rating: ±80 V


• Switch current rating: 20 mA


• Analog bus voltage capability: up to 300 V signals


• Scanning rate: up to 1000 channels per second


• Overvoltage protection: circuitry detects faults <100 V and limits current


• Per-channel input overvoltage protection with series resistor Switching Architecture


• Optically isolated FET relays with solid-state, long-life operation


• Four armature Analog Bus relays for internal DMM connection


• Break-before-make switching prevents signal contention during scans


• Hardware safety interlock automatically opens Analog Bus relays upon D-sub interlock pin loss of continuity Physical & Interface


• Dimensions: 280 mm L × 170 mm W × 27 mm H


• 50-pin D-Sub connectors


• Compatible with Keysight 34925T terminal block accessories

Key Features

• High channel density (40/80) in compact form factor


• Optical isolation provides noise rejection in demanding environments


• Interlock safety mechanism protects against unintended signal presence on analog buses


• 1:N closure architecture with overvoltage protection ensures relay longevity and system integrity


• Break-before-make operation eliminates transient coupling during channel transitions

Typical Applications Multi-channel sensor switching, high-speed data acquisition, automated parametric testing, precision signal conditioning, and systems requiring signal isolation with fast channel scanning.

Compatibility & Integration The 34925A integrates directly into the Keysight 34980A mainframe. Terminal block options (34925T series) simplify DUT connections and enable modular test system configuration.