SNLS504G October 2015 – June 2026 DP83867CS , DP83867E , DP83867IS
PRODUCTION DATA
The DP83867 has several internal clocks, including the local reference clock, the Ethernet transmit clock, and the Ethernet receive clock. An external crystal or oscillator provides the stimulus for the local reference clock. The local reference clock acts as the central source for all clocking in the device.
The local reference clock is embedded into the transmit network packet traffic and is recovered from the network packet traffic at the receiver node. The receive clock is recovered from the received Ethernet packet data stream and is locked to the transmit clock in the partner.
Using the I/O Configuration register (address 0x0170), configure the DP83867 to output these internal clocks through the CLK_OUT pin. By default, the output clock is synchronous to the XI oscillator / crystal input. The default output clock is an excellent choice for use as the reference clock of another DP83867 device. Through registers, configure the output clock to be synchronous to the receive data at the 125MHz data rate or at the divide by 5 rate of 25MHz. Configure the clock to output the line driver transmit clock. When operating in 1000Base-T mode, configure the output clock for any of the four transmit or receive channels.
Disable the output clock using the CLK_O_DISABLE bit of the I/O Configuration register.