Smart Extender LeCroy VME Module

The Teledyne / LeCroy / Catalyst VME-100 Hot Swap VME Extender Module can be used in any VME bus. The circuitry designed on this board isolates all the motherboard voltages and the signals from the UUT by means of the On-Off switch or the external input, therefore eliminating the requirement for turning the system On and Off and repeated rebooting during the test and characterization process.

The VME-100 is a full size extender board with support brackets for securing the extender board to the chassis. The extender, in addition to the current limiting for the +5V, also has fuses for the +12V and -12V to protect the bus from any damages due to shorts from the Unit-Under-Test. The current limiting for the +5V is set to 6 Amp at the factory, but it can be increased or decreased by changing a resistor on the board.

Voltage margin testing of the VME boards are facilitated when using the VME-100 extender. By removing 3 pre-assembled jumpers on this board, the system bus voltages will be isolated off and external voltages can be connected via the external inputs. All features including the +5V current limiting and +5V current measurement circuitry will still be operating in this mode.

The On-Off power circuitry keeps the Unit-Under-Test isolated from the motherboard until the +5V has reached to at least 3 Volts during the power up. This feature assures that the bus will not hang due to the Unit-Under-Test not having adequate power. This circuitry also isolates the Unit-Under-Test from the bus during the power down as soon as the +5V reaches down to 3 Volts. All the Voltages are ramped up and down during the power up and power down to assure no glitches are generated due to any sudden power cycling.

When the system power is turned off, the VME daisy chain signals are passed to the next slot, allowing the system operation to continue. On-board power-on reset also generates the system reset required for initializing the Unit-Under-Test, after each power on. On-board current to voltage circuitry is provided to allow +5V current measurement, using only a Voltmeter, at a two point terminal.

The VME-100 board requires no software to operate. Simply, plug it in and use it. The board supports the entire Address range and all modes of operation, including DMA mode. The total propagation delay, for all signals, is typically less than a nanoseconds from the bus to the Unit-Under-Test.