VSC8541XMV-05 datasheet(17/101 Pages) MICROCHIP

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Functional Descriptions

VMDS-10513 VSC8541-02 Datasheet Revision 4.1

In order to further reduce power consumption and EMI, the user may elect to choose a slower edge rate

than recommended if the end application supports it.

The MAC interface signal rise/fall times can be changed by writing to register bits 27E2.7:5. The typical

change in edge rate for each setting at various VDDMAC voltages is shown in the following table.

These values are based on measurements performed on typical silicon at nominal supply and room

temperature settings.

3.3

Hardware Mode Strapping and PHY Addressing

The VSC8541-02 device provides hardware-configured modes of operation that are achieved by

sampling output pins on the rising edge of reset and externally pulling the pin to a logic HIGH or LOW

(based on the desired configuration). These output pins are required by the device as inputs while

NRESET is asserted and the logic state of the pin is latched in the device upon de-assertion of NRESET.

To ensure correct operation of the hardware strapping function, any other device connected to these pins

must not actively drive a signal onto them.

The following table describes the pins used for this purpose and their respective modes.

2.5 V

100

1.8 V

111

1.5 V

111

Table 5 •

MAC Interface Edge Rate Control

Edge Rate Change (VDDMAC)

3.3V

2.5V

1.8V

1.5V

111 (fastest)

Default

(recommended)

Default

(recommended)

110

–2%

–3%

–5%

–6%

101

–4%

–6%

–9%

–14%

100

–7%

(recommended)

–10%

(recommended)

–16%

–21%

011

–10%

–14%

–23%

–29%

010

–17%

–23%

–35%

–42%

001

–29%

–37%

–52%

–58%

000 (slowest)

–53%

–63%

–76%

–77%

Table 6 •

Hardware Mode Strapping and PHY Addressing

Pin(s)

Operation Mode

CLKOUT

Enable/disable CLKOUT signal

RX_CLK

Managed or unmanaged mode

RXD0

Signal A

RXD1

Signal B

RXD2

Signal C

RXD3

Signal D

Table 4 •

Recommended Edge Rate Settings (continued)

VDDMAC Voltage

Edge Rate Setting

VSC8541XMV-05 Datasheet(PDF) 17 Page - Microchip Technology

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