EVM Dual BoC
BoC - Quick Start Guide
Revision 0.4 – preliminary
Page
10 of 31
Table 2: JP5 & JP4 (Board A & B) I2C Switch Configuration
JP4
JP5
EEPROM Address
ON
OFF
ON
OFF
Switch
A0
X
X
1-6
A1
X
X
2-5
A2
X
X
3-4
XI.
Common REFCLK Source
Your BoC has the capability of supplying a common REFCLK both EVM’s. This common
REFCLK is generated on the BoC and sourced from a dedicated differential oscillator
through a high performance 1:2 low clock jitter buffer (U12). On your BoC is JP10, this
header and shunt are used to enable or disable the differential oscillator on the BoC. By
default the shunt is applied on this header, placing the oscillator input to the clock mux in
a Hi-Z state.
Not all EVM’s directly support this feature, future EVM’s will incorporate this feature and
have it connected to a EVM clock source (typically att the secondary clock source input)
through the AMC connectors and respective nets. The clock routing is skew matched
between AMC headers to within 5ps.
a. REFCLK Oscillator Enable Header [19]
The following table defines the possible configurations for JP10. JP10 is used to enable
or disable the 30.72MHz differential clock source (U14) input to the CDCLVP1102 which
is intended to provide a common clock source to both EVM’s for the REFCLK. By default
the shunt is installed and the REFCLK source is disabled.
Table 3: JP10 REFCLK Enable Header
JP10
ON
Disabled
OFF
Enabled
OFF
ON
1
X
2
X
b. REFCLK Signal Levels
The output of the low jitter 1:2 clock buffer is LVPECL (low voltage PECL). As such this
logic level may not be adequate for your DSP. Consult your DSP data manual and the
data manual for the CDCLVP1102 before using this hardware. Prior to proceeding it will
also be necessary to confirm that the EVM clock source input (that the REFCLK is
connecting to) is AC coupled and/or biased. Your BoC REFCLKp/n outputs are
not
AC
WARNING
: The I2C Interface is intended to operate at 3.3V, Confirm that
your EVM level shifts this into to correct DSP range before using this interface
or connecting your EVM’s.
CAUTION
: Confirm that your EVM supports this interface and that the
number of interfaces as well as the pinout locations is supported correctly.