DP83849ID datasheet(14/98 Pages) NSC

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MII_MODE_A (RX_DV_A)

SNI_MODE_A (TXD3_A)

MII_MODE_B (RX_DV_B)

SNI_MODE_B (TXD3_B)

S, O, PD

MII MODE SELECT: This strapping option pair determines the

operating mode of the MAC Data Interface. Default operation (No

pull-ups) will enable normal MII Mode of operation. Strapping

MII_MODE high will cause the device to be in RMII or SNI modes

of operation, determined by the status of the SNI_MODE strap.

Since the pins include internal pull-downs, the default values are

0. Both MAC Data Interfaces must have their RMII Mode settings

the same, i.e. both in RMII mode or both not in RMII mode.

The following table details the configurations:

LED_CFG_A

(CRS_A/CRS_DV_A)

LED_CFG_B

(CRS_B/CRS_DV_B)

S, O, PU

LED CONFIGURATION: This strapping option determines the

mode of operation of the LED pins. Default is Mode 1. Mode 1 and

Mode 2 can be controlled via the strap option. All modes are con-

figurable via register access.

See Table 3 on page 20 for LED Mode Selection.

MDIX_EN_A (RX_ER_A)

MDIX_EN_B (RX_ER_B)

S, O, PU

MDIX ENABLE: Default is to enable MDIX. This strapping option

disables Auto-MDIX. An external pull-down will disable Auto-MDIX

mode.

ED_EN_A (RXD3_A)

ED_EN_B (RXD3_B)

S, O, PD

Energy Detect ENABLE: Default is to disable Energy Detect

mode. This strapping option enables Energy Detect mode for the

port. In Energy Detect mode, the device will initially be in a low-

power state until detecting activity on the wire. An external pull-up

will enable Energy Detect mode.

CLK2MAC_DIS (RXD2_A)

S, O, PD

Clock to MAC Disable: This strapping option disables (floats) the

CLK2MAC pin. Default is to enable CLK2MAC output. An external

pullup will disable (float) the CLK2MAC pin. If the system does not

require the CLK2MAC signal, the CLK2MAC output should be dis-

abled via this strap option.

Signal Name

Type

Pin #

Description

MII_MODE SNI_MODE

MAC Interface

Mode

MII Mode

RMII Mode

10 Mb SNI Mode

DP83849ID Datasheet(PDF) 14 Page - National Semiconductor (TI)

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