1.3 Clock Interface
Signal Name
Type
Pin #
Description
X1
I
34
CRYSTAL/OSCILLATOR INPUT: This pin is the primary clock
reference input for the DP83848I and must be connected to a 25
MHz 0.005% (+50 ppm) clock source. The DP83848I supports ei-
ther 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 refer-
ence input for the RMII mode and must be connected to a 50 MHz
0.005% (+50 ppm) CMOS-level oscillator source.
X2
O
O
33
25
CRYSTAL OUTPUT: This pin is the primary clock reference out-
put 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.
25MHz_OUT
25 MHz CLOCK OUTPUT:
In MII mode, this pin provides a 25 MHz clock output to the sys-
tem.
In RMII mode, this pin provides a 50 MHz clock output to the sys-
tem.
This allows other devices to use the reference clock from the
DP83848I without requiring additional clock sources.
1.4 LED Interface
See Table 3 for LED Mode Selection.
Signal Name
LED_LINK
Type
Pin #
Description
S, O, PU
28
LINK LED: In Mode 1, this pin indicates the status of the LINK.
The LED will be ON when Link is good.
LINK/ACT LED: In Mode 2 and Mode 3, this pin indicates transmit
and receive activity in addition to the status of the Link. The LED
will be ON when Link is good. It will blink when the transmitter or
receiver is active.
LED_SPEED
S, O, PU
S, O, PU
27
26
SPEED LED: The LED is ON when device is in 100 Mb/s and OFF
when in 10 Mb/s. Functionality of this LED is independent of mode
selected.
LED_ACT/COL
ACTIVITY LED: In Mode 1, this pin is the Activity LED which is
ON when activity is present on either Transmit or Receive.
COLLISION/DUPLEX LED: In Mode 2, this pin by default indi-
cates Collision detection. For Mode 3, this LED output may be
programmed to indicate Full-duplex status instead of Collision.
11
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