Pci Board; Mib (Module Interface Board) - Agilent Technologies 16800 Series Service Manual

PCI board

MIB (Module Interface Board)

16800 Series Portable Logic Analyzers Service Guide
Power supply
The frame uses two modular power supplies to provide the
six DC voltage rails: - 12 V, +12 V, - 5 V, +5 V, - 3.3 V, +3.3 V.
These rails use remote sensing to maintain .01% load
regulation. The module slots are limited to 100 W each and
the instrument as a whole to 600 W.
The frame has a "soft" power on/off algorithm. Pressing the
power switch notifies the CPU to either wake up or power
down. The CPU then in turn drives the signal line which
actually turns the supplies on or off. A PLD monitors this
process and will force a power down after approximately
two minutes if the CPU does not respond. The small portion
of circuitry involved in this process is powered from an
auxiliary +5 V which is always present as long as the
instrument is plugged in. Additional logic monitors the
voltage levels on the six rails and will also cause an
immediate power down if any one drops below about 90% of
regulation. Power down can also be caused by an over
temperature sense circuit. In this case, the PLD notifies the
CPU, the user receives a warning window, and a soft power
down is started. Again, the PLD will force a power down if
the CPU does not soft power down in about two minutes.
The PCI Board plugs into a CPU motherboard PCI slot,
providing the interface between the CPU motherboard and
the logic analyzer. On the PCI board is a PCI bridge chip
used to provide an electrical interface between the CPU PCI
slot bus and the two PCI devices located on the Module
Interface Board. A TI2050A PCI bridge chip is used to
connect to the primary PCI bus on the CPU motherboard
connector and provides a secondary PCI bus, which is
connected via an 80- pin high- density cable from this PCI
board to the Module Interface Board.
Top level function
The MIB contains all of the logic analyzer frame specific
hardware. This includes all circuits necessary to interface
with measurement modules, interface with the front panel
knob and keys, monitor frame functions, and interface to the
CPU motherboard via the PCI board. It also performs power
distribution and numerous interconnects.
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Theory of Operation
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