
CYV15G0404DXB Evaluation Board
Users Guide
Page 18 of 56
6.4 Reference Clock Input Options
The reference clock signal, REFCLKx, can have three different types of input: Single-ended SMA, Differential SMA, and the
Crystal Oscillator. Figure 6-4 shows the SMA connectors, Crystal Oscillator, and headers to probe REFCLKx.
Crystal Oscillator
The crystal oscillator is the default source for the REFCLKx signal. It provides a single-ended input. Each channel has an oscillator
with a different frequency. The default frequencies for each channel are: channel A runs at 125.0 MHz, channel B at 106.25 MHz,
channel C at 27.0 MHz, and channel D at 20.0 MHz. When attaching the oscillator, line up the sharp corner of the oscillator with
the sharp corner of the white outline on the silkscreen (see Figure 6-4).
Single-ended SMA
To use the single-ended SMA option, connect an appropriate cable to either the REFCLKx+ or REFCLKx- SMA connector (see
Figure 6-4). The crystal oscillator for that channel must also be disconnected from the 14-pin DIP socket.
Differential SMA
To use the differential SMA option, connect appropriate cables to both the REFCLKx+ and REFCLKx- SMA connectors (see
Figure 6-4). The crystal oscillator for that channel must also be disconnected from the 14-pin DIP socket.
Table 6-1. Device Control Latch Configuration Example
ADDR Chnl Type DATA7 DATA6 DATA5 DATA4 DATA3 DATA2 DATA1 DATA0 Reset Value
10
(1010b)
DSSDASEL2
D[1] = ‘1’
SDASEL2
D[0] = ‘0’
SDASEL1
D[1] = ‘1’
SDASEL1
D[0] = ‘1’
ENCBYP
D = ‘1’
TXCKSEL
D = ‘0’
TXRATE
D = ‘1’
GLEN10
= ‘0’
10101101
Figure 6-4. Top View of REFCLK Connectors
Ground
Probe of REFCLKx-
Probe of REFCLKx+
SMA Connector for
SMA Connector for
Crystal Oscillator
Corner of silk screen
outline
Corner of oscillator
REFCLKx- input
REFCLKx+ input
[+] Feedback
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