VM600 MPS hardware manual (standard version) MAMPS-HW/E 4 - 25
Edition 17 - February 2018
MPC4 power-up sequence
MPC4 / IOC4T CARD PAIR
4.8 MPC4 power-up sequence
The MPC4 card's power-up sequence is initiated by either of the following events:
• The MPC4 being inserted into the ABE04x rack when the latter is powered up (that is,
the "live insertion" situation).
• Power being re-established after a power-down or a power failure.
4.8.1 Power-up after live insertion
A +5 V
DC
pre-charge supply is used to enable live insertion of MPC4 cards. This voltage is
supplied to the MPC4 from the system backplane. It is passed to the MPC4 module via three
pins on connector P1 (see Figure 3-3). These pins are slightly longer than the other VME bus
connector pins (ABE04x only).
When a module is inserted into a MPS rack that is powered up, these longer pins make
contact first (typically 200 ms before the other pins). During this time, the +5 V
DC
pre-charge
supply is used to power up all the +5 V
DC
parts on the module. This ensures that when the
bus driver makes contact with the running VME bus, the circuitry is already at approximately
the correct voltage. In this way no glitches are produced on the VME bus power, address or
data pins.
Once the rest of the pins (including the standard +5 V
DC
supply) make contact, no further
power is drawn from the +5 V
DC
pre-charge supply.
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