5-2
MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
MOTOROLA
Reference Clock Configuration
5.1
Reference Clock Configuration
The MC92603 provides the option of either a differential or single-ended source for the
reference clock input. The frequency of the clock signal applied to these inputs along with
the settings on the configuration inputs determine the speed at which the serial links
operate. Also, the legal ranges of reference clock frequencies vary depending on the state
of the half-speed enable, HSE, input. Table 5-1 shows the allowable ranges for each
configuration.
The internal reference clock may be driven by either a 3.3-V (LVTTL) input
(TTL_REF_CLK) or by a pair of LVPECL differential inputs (REF_CLK_P and
REF_CLK_N). If the USE_DIFF_CLOCK input is high, the LVPECL differential inputs,
REF_CLK_P and REF_CLK_N, are used as the clock source. If USE_DIFF_CLOCK is
low, the TTL_REF_CLK input is used as the clock source.
The differential reference clock inputs, REF_CLK_P/N, may also be driven by a
single-ended source. The REF_CLK_N input must be set at V
REF
= 1.25 V for a
single-ended operation of REF_CLK_P and must be connected to its own reference voltage
circuit.
When using the differential LVPECL inputs, the unused input, TTL_REF_CLK, shall be
terminated low. When using the single-ended TTL input, the differential LVPECL
reference clock inputs shall be terminated low.
5.2
Startup
The MC92603 begins a startup sequence on application of the reference clock input to the
device. This is considered a cold startup. The cold startup sequence is as follows:
1. PLL startup
2. Receiver initialization and byte alignment
3. Word alignment (if enabled)
4. Run
Table 5-1. Legal Reference Clock Frequency Ranges
HSE
Reference Frequency
Min (MHz)
Reference Frequency
Max (MHz)
Link Transfer Rate
(Gigabaud)
Low
95.00
135.0
0.95–1.35
High
47.50
67.50
0.475–0.675
Содержание MC92603
Страница 18: ...xviii MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA ...
Страница 26: ...1 8 MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA References ...
Страница 40: ...2 14 MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA Transmitter Redundant Link Operation ...
Страница 116: ...A 2 MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA ...
Страница 126: ...C 2 MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA ...
Страница 130: ...Glossary 4 MC92603 Quad Gigabit Ethernet Transceiver Reference Manual MOTOROLA ...