XRT8001IP datasheet(19/48 Pages) EXAR

19 / 48 page

XRT8001

Rev. 1.01

In the “High Speed – Reverse” Mode

In the “High Speed – Reverse” Mode, the XRT8001

WAN Clock will be receiving a 64kHz clock signal via

the “FIN” input pin. The XRT8001 WAN Clock will, in

response, generate an “M x 2.048MHz” clock via the

CLK1 and CLK2 output pins. These five (5) bit-fields

within Command Register CR2 are used to define the

value “M” for the CLK1 output.

Note: The only acceptable values for “M” are 1, 2, 4, or 8.

3.2.4 Command Register CR3 (Address = 0x03)

D4 – D0 (SEL2[4:0])

These bit-fields are used to support configuration

implementation for the “Forward/Master” and the “High

Speed – Reverse” Modes of operation.

In the “Forward/Master” Mode

In the “Forward/Master” Mode, the XRT8001 WAN

Clock will output either a “K x 56kHz” or a “K x 64kHz”

clock signal via the CLK2 output pin. These five (5) bit-

fields within Command Register CR3 are used to define

the value of “K” for the CLK2 Output. As a conse-

quence, the XRT8001 can be configured to generate a

maximum frequency of “32 x 56kHz” or “32 x 64kHz” via

the CLK2 output pin.

In the “High Speed – Reverse” Mode

In the “High Speed – Reverse” Mode, the XRT8001

WAN Clock will be receiving a 64kHz clock signal via

the “FIN” input pin. The XRT8001 WAN Clock will, in

response, generate an “M x 2.048MHz” clock via the

CLK1 and CLK2 output pins. These five (5) bit-fields

within Command Register CR3 are used to define the

value “M” for the CLK2 output.

Note: The only acceptable values for “M” are 1, 2, 4, or 8.

3.2.5 Command Register CR4 (Address = 0x04)

D4 – SYNCEN (SYNC Output Driver Enable Select)

This “read/write” bit-field permits the user to enable or

disable the Driver associated with the SYNC output

pin. Setting this bit-field to “1” enables this Driver.

Setting this bit-field to “0” disables this Driver.

D3 – CLK1EN (CLK1 Output Driver Enable Select)

This “read/write” bit-field permits the user to enable or

disable the Driver associated with the CLK1 output pin.

Setting this bit-field to “1” enables this Driver. Setting

this bit-field to “0” disables this Driver.

D2 – CLK2EN (CLK2 Output Driver Enable Select)

This “read/write” bit-field permits the user to enable or

disable the Driver associated with the CLK2 output pin.

Setting this bit-field to “1” enables this Driver. Setting

this bit-field to “0” disables this Driver.

D1,D0–LDETDIS[2:1]–LockDetectorOutput Control

The combination of these two bit-fields permit the user

to specify the signal that will be output via the

LOCKDET output pin. The user’s options are shown in

Table 3.

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