Agilent/Keysight 34945EXT

The Keysight/Agilent 34945EXT is an extender board that expands the switching and multiplexing capabilities of the 34945A and L4445A Microwave Switch/Attenuator Drivers, as well as the 34980A Multifunction Switch/Measure Unit. It enables control of external microwave switches and attenuators through 64 independently driven channels supporting low-side drive, TTL drive, and LED indicator modes. The board accommodates distribution boards (Y1150A, Y1151A, Y1152A, Y1153A, Y1155A, Y1156A) for simplified external component wiring, making it ideal for scalable automated test and data acquisition systems requiring external switch control.

– Technical Specifications

Switch Drive Channels: 64 channels total

Drive Modes:
• Low-side drive: 30 V max off-voltage, 500 µA off-leakage, 600 mA max on-current, 0.5 V @ 600 mA on-voltage
• TTL drive: 3 V Hi output @ 2 mA, 0.4 V Lo output @ 20 mA input
• LED indicators: 5 V nominal supply, 5 mA nominal drive current (programmable 1–20 mA), 0.8 V compliance voltage

Position Indicator Sense Inputs: 64 channels with 0.8 V max Lo threshold, 2.5 V min Hi threshold, >100 kΩ input resistance (Vin ≤ 5 V), >20 kΩ (Vin > 5 V), 30 V maximum input voltage

Power Supply:
• From 34945A/L4445A: 24 V nominal, 100 mA continuous + 200 mA pulse (15 ms, 25% duty cycle)
• External connection: 4.75 V to 30 V range, 2 A current limit
• Single voltage level per board (±24 V, +12 V, or +5 V)

Switching Capacity: Drives up to 64 switch coils (equivalent to 32 standard SPDT switches per 34945A/34945EXT combination). Up to seven additional 34945EXT boards can be added with external power; each board accommodates 4 distribution boards.

– Key Features

• Dual power options: internal (from master driver) or external supply
• Multi-level voltage support for diverse switch coil requirements
• High input impedance sense inputs tolerate voltages to 30 V
• Programmable LED drive current (1–20 mA range)
• Scalable architecture supports up to eight total extender boards per master unit

– Typical Applications

• Microwave switch matrix expansion
• Attenuator control in RF test systems
• Large-scale multiplexing for automated measurement systems
• External relay and solenoid actuation

– Compatibility & Integration

Primary compatibility with Keysight/Agilent 34945A and L4445A drivers; integrates with 34980A Multifunction Switch/Measure Unit. Requires external power supply for slave modules and installations external to L4490A or L4491A chassis.