dp83848qsqx/nopb National Semiconductor Corporation, dp83848qsqx/nopb Datasheet - Page 8

• Manufacturer Part Number: dp83848qsqx/nopb
• Description: Phyter Extended Temperature Single Port 10/100 Mb/s Ethernet Physical Layer Transceiver
• Manufacturer: National Semiconductor Corporation

www.national.com
Signal Name
CRS/
CRS_DV
COL
X1
X2
25MHz_OUT
Signal Name
7.3 CLOCK INTERFACE
S, O, PU
S, O, PU
Type
Type
O
O
I
Pin #
33
35
Pin #
28
27
21
MII CARRIER SENSE: Asserted high to indicate the receive medium is non-idle.
RMII CARRIER SENSE/RECEIVE DATA VALID: This signal combines the RMII Carrier and
Receive Data Valid indications. For a detailed description of this signal, see the RMII
Specification.
MII COLLISION DETECT: Asserted high to indicate detection of a collision condition
(simultaneous transmit and receive activity) in 10 Mb/s and 100 Mb/s Half Duplex Modes.
While in 10BASE-T Half Duplex mode with heartbeat enabled this pin is also asserted for a
duration of approximately 1µs at the end of transmission to indicate heartbeat (SQE test).
In Full Duplex Mode, for 10 Mb/s or 100 Mb/s operation, this signal is always logic 0. There is
no heartbeat function during 10 Mb/s full duplex operation.
RMII COLLISION DETECT: Per the RMII Specification, no COL signal is required. The MAC
will recover CRS from the CRS_DV signal and use that along with its TX_EN signal to determine
collision.
CRYSTAL/OSCILLATOR INPUT: This pin is the primary clock reference input for the
DP83848Q and must be connected to a 25 MHz 0.005% (±50 ppm) clock source. The
DP83848Q supports either an external crystal resonator connected across pins X1 and X2,
or an external CMOS-level oscillator source connected to pin X1 only.
RMII REFERENCE CLOCK: This pin is the primary clock reference input for the RMII mode
and must be connected to a 50 MHz 0.005% (±50 ppm) CMOS-level oscillator source.
CRYSTAL OUTPUT: This pin is the primary clock reference output to connect to an external
25 MHz crystal resonator device. This pin must be left unconnected if an external CMOS
oscillator clock source is used.
MII 25 MHz CLOCK OUTPUT: This pin provides a 25 MHz clock output to the system. This
allows other devices to use the reference clock without requiring additional clock sources.
RMII 50 MHz CLOCK OUTPUT: Tthis pin provides a 50 MHz clock output to the system.
For RMII mode, it is not recommended that the system clock out be used as the reference
clock to the MAC without first verifying the interface timing. See AN-1405 for more details.
8
Description
Description