VXI?Corporation F80 Especificaciones descargar pdf (Pagina 30)

Page 30 Pentek Model 6526 Operating Manual

Rev. A

2.4 Model 6526 Front Panel (continued)

2.4.2 Sync Bus (continued)

2.4.2.4 Sync Bus Equivalent Circuit

Each of the sync lines is connected to each of the following items:

1) A Low Voltage Differential SCSI−type active terminator

(Unitrode UCC5630MWP). This device is normally disabled at

power−up, but must be enabled ONLY in the unit that is at the

opposite end of the Sync bus from the sync master. The

termination is enabled by setting the Sync Term bit in the Sync

Bus Control Register (see Section 3.4.2) to the logic '1' state.

2) The output of a 3V Differential Line Driver (National

Semiconductor DS90LV031A). This device is also normally

disabled at power−up, and must be enabled ONLY in the

Model 6526 that is the sync master. The driver is enabled by

setting the Sync Master bit in the Sync Bus Control Register (see

Section 3.4.2) to the logic '1' state. Devices should be arranged

in your card cage such that the sync master drives one end of

the sync cable, and the unit with the terminator enabled is at

the opposite end of the sync cable.

3) The input of a 3V Differential Line Receiver (National

Semiconductor DS90LV032A). This device is always enabled

in all Model 6526’s.

The Sync bus equivalent circuit is shown schematically in

Figure 2−9, below.

Figure 2−9: Sync Bus Equivalent Circuit

D_SyncN

UCC

5630

MWP

ctive

Term

L+

L–

SyncN

M_SyncN

DS90LV032A

Diff. Line Driver

DS90LV031A

Diff. Line Receiver

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VXI?Corporation F80 Especificaciones Pagina 30