DP83848C_07 datasheet(11/82 Pages) NSC

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1.3 Clock Interface

1.4 LED Interface

See Table 3 for LED Mode Selection.

Signal Name

Type

Pin #

Description

CRYSTAL/OSCILLATOR INPUT: This pin is the primary clock

reference input for the DP83848C and must be connected to a 25

MHz 0.005% (+50 ppm) clock source. The DP83848C 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 refer-

ence 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 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

DP83848C without requiring additional clock sources.

Signal Name

Type

Pin #

Description

LED_LINK

S, O, PU

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

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

S, O, PU

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.

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