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SIS3400 64 Channel TDC/time stamp generator


The SIS3400 VME board is designed for continuous time measurements with time bin lengths down to 50 ns. The primary focus of the card is on the readout of Neutron Time of Flight spectrometers with up to 1152 detector channels in a single crate VME system. Other applications comprise trigger time stamping as well as arbitrary medium resolution long term processes. The module is a single width (4 TE), 6U VME card, the inputs are implemented with 50 Ohm impedance metric coax. connectors with TTL input level. In the Neutron TOF readout application case the front end logic stores 64-bit words with one or more bit status changes in a derandomizer FIFO. In parallel the time stamp is stored in a time stamp FIFO. The event formatting logic can be operated in different modes. In single word mode it extracts bits with status change, and converts the bit and board number into a unique address, which is stored in a 32-bit wide ouput word together with the 20-bit time stamp. Time slices with n bit changes result in n 32-bit words written to the cards ouput FIFO. The VME CPU can gather data from the ouput FIFOs upon the FIFO not empty or FIFO half full condition, depending on the overall system design this can be done with FIFO interrupt handling or polling.


SIS3400 Feature/Overview

  • 64 channels
    20-bit time bin counter with wrap around counter (32-bit with firmware 0xB)
    Down to 50 ns time bin resolution
    TTL input levels
    external/internal clock
    external/software time reset/zero
    external/internal software inhibit
    Leading Edge/Trailing Edge
    Derandomizer FIFO
    Output FIFO
    FIFO and wrap around interrupts
    VME64x Connectors
    VME64x Front panel
    VME64x Side Shielding
    VME64x extractor handles (on request)


Metric koax. connector input version

  • TTL 2mm metric koax. control in/outputs
    TTL 2mm metric koax. inputs


RS485 (LVDS optional) inputs via two 68-pin "SCSI" connectors

  • TTL LEMO control in/outputs
    RS485 (LVDS optional) inputs via two 68-pin "SCSI" connectors


VME properties:

The unit is in compliance with the VME standard, it supports the following VME features:


  • A24/A32 D32/BLT32/BLT64
  • Base address A31-A24 settable via two rotary switches
  • VME64xP geographical addressing
  • VME64xP LED set (PAR)
  • VME64xP hot swap


Block Diagram:




8 LEDs are implemented to visualise the board status.


  • VME Access
  • Power
  • Ready (logic configured)
  • User (set/cleared under program control)
  • Disable (or of external/internal disable)
  • Derandomiser FIFO overflow(error condition)
  • Output FIFO overflow (error condition)
  • Event (time slice with bit change)



Metric coax. connector: