Micrel SY87725L, Manual

Page: 10 / 14

Micrel, Inc. SY87725L Evaluation Board
July 2008 10 M9999-071108-B
hbwhelp@micrel.com or (408) 955-1690
Normal Data Flow
This is the normal operating mode and verifies the receive
and transmit sections independently, which means any
combination of the allowed receive and transmit data rates can be used. The switch settings below select the
frequencies and data rates specified in the block diagram.
Figure 6. Switch Settings for Normal Data Flow
Switch Settings Function
RCV_DDRSEL = 0 Sets Clkout at parallel data rate
RCV_CTRL0/1 = 11 Selects the normal receive data
path
RCV_FSEL0/1 = 11 Sets receive CDR frequency to
2.48832Gbps (For other
frequencies, refer to Receive
Frequency Selection Table on
page 7 of SY87725L Data
sheet.)
XMT_FSEL0/1 = 01 Sets parallel data rate to be
1.24416Gbps/4
TESTb = 1 Disables factory test mode
(enables normal operation)
CD = 1 Enables clock and data
recovery
REFFREQSEL = 1 Selects RefClk of 155.52MHz
XMT_CTRL0/1 = 11 Selects the normal transmit
data path
XMT_DDRSEL = 1 Selects Clkin to be at parallel
data rate
Table 7. Required Switch Settings for
Normal Data Flow