XRT8001IP datasheet(45/48 Pages) EXAR

45 / 48 page

XRT8001

Rev. 1.01

3) Both the XRT8001 and XRT8000 can be configured

to accept “Fractional T1/E1” rate clock signals (e.g., K

x 64kHz) and synthesize either a 1.544MHz or

2.048MHz clock signal.

However, the XRT8001 can also synthesize “Frac-

tional T1/E1” rate clock signals, when provided with

either a 1.544MHz or 2.048MHz clock signal

LOCKDET Pin Function

Description of LOCKDET pin’s role

LOCK Condition of both PLL1 AND PLL2

The LOCKDET output pin toggles “HIGH” only if both (of if the only

enabled) PLLs are “In-LOCK”.

The LOCKDET output pin will toggle “LOW” if any one of the PLLs

are out of LOCK.

NOTE: In this case, the LOCKDET output of the XRT8001

behaves identical to that of the XRT8000.

LOCK Condition of PLL1 Only

The LOCKDET output pin toggles “HIGH” only if PLL1 is in the “In-

LOCK” condition.

LOCK Condition of PLL2 Only

The LOCKDET output pin toggles “HIGH” only if PLL2 is in the “In-

LOCK” condition.

Forced to “LOW”

The LOCKDET output pin is pulled “LOW” regardless of the “Lock”

condition of the two PLLs.

NOTE: The XRT8000 has an additional divide by 8 block which is not included in the XRT8001.

Table 15: Selectable Functions of the LOCKDET Output Pin in the XRT8001

4) The XRT8001 permits the user to determine the

exact role of the LOCKDET output pin. The on-chip

Command Register (within the XRT8001) permits the

user to configure the LOCKDET output pin to have the

functions listed below.

In the XRT8000, the LOCKDET output pin is pulled

HIGH only when both XRT8000 PLLs are “in-lock”.

XRT8001IP Datasheet(PDF) 45 Page - Exar Corporation