GX3290 Datasheet, PDF (24/47 Pages) Semtech Corporation – 290 x 290 3.5Gb/s Crosspoint Switch

When using dynamic configuration, updates to the switch matrix are first written to the
DYNAMIC[287:0] registers where they are held until the corresponding update strobe
signal, selected using the UPDATE_SELECT[287:0] bits in the DYNAMIC[287:0]
registers, changes state from LOW-to-HIGH.
The source for the update strobes can either be via external pins (UPDATE_EN[7:0]) or
register bits (SOFT_UPDATE_EN[7:0]) as selected by the setting of the
SOFTWARE_UPDATE_ENABLE bit in the CONTROL_SETUP register. Setting the
SOFTWARE_UPDATE_ENABLE bit LOW causes the device to use the external
UPDATE_EN[7:0] pins as update strobes for the switch matrix. Setting the
SOFTWARE_UPDATE_ENABLE bit HIGH causes the device to use the
SOFT_UPDATE_EN[7:0] bits as update strobes for the switch matrix. See Section 6 of
the Crosspoint (GX3290 and family) Reference Manual (for CSRs) document.
When the selected update strobe signal (or bit) transitions from LOW-to-HIGH, the state
of all the outputs configured to respond to that update strobe signal (or bit) are updated
at that time.
Regardless of which register set is used to configure the switch matrix, the current
configuration of the matrix is always available by reading back the ACTIVE[287:0]
registers.
Note: The MON0 and MON1 outputs can not be powered up/down, switched, or
polarity inverted dynamically (Dynamic Configuration). They can only be configured in
the Active Configuration mode described above using the settings in registers 0x320h
and 0x321h, respectively. Also, the MON0 and MON1 outputs are terminated to the
VCC_25_A supply.
4.4 Propagation Delay
The propagation delay is dependent on the path that the signal takes through the device.
Although the delay difference from the shortest path to the longest path could be up to
5.5ns, this difference is at a minimum for connections from inputs numerically close
together and on the same side of the device to outputs that are numerically close
together and on the same side of the device. Propagation delay differences of less than
750ps can be expected when the inputs are adjacent in the ballout and the outputs are
also adjacent in the ballout.
Note: The 750ps propagation delay difference (skew) between physically adjacent
channels is guaranteed by simulation.
4.5 Using Multiple Strobes
The GX3290 has eight fully-independent update strobes.
Outputs 287 to 0 can be assigned to one of the eight strobes through the setting of the
UPDATE_SELECT bits in the corresponding DYNAMIC[287:0] register. The input
signal selection, output power switching and signal inversion will take effect on the
LOW-to-HIGH edge of its assigned strobe signal or bit. This allows different portions of
the crosspoint to be switched at different points in time. This is particularly useful in
systems supporting multiple data or video formats, where the switch point/time varies
from format to format.
GX3290 290 x 290 3.5Gb/s Crosspoint
Final Data Sheet Rev. 2
GENDOC-053317 March 2013
www.semtech.com
24 of 47
Proprietary & Confidential