PM4541 datasheet(6/46 Pages) PMC

6 / 46 page

TELECOM STANDARD PRODUCT

PMC-Sierra, Inc.

PM4541 T1XC-EVBD

PMC-920314

ISSUE 2

T1XC EVALUATION DAUGHTERBOARD

2.3

Decode Logic

Decode logic is provided on the daughterboard to give memory mapped access to

all of the registers within both T1XCs. Registers within the "east" T1XC are

accessible starting at address C000H. Registers within the "west" T1XC are

accessible starting at address C100H. Additional chip selects are provided for

addresses C200H-C2FFH and C300H-C3FFH for use on the prototype area.

2.4

DIP Switches

The DIP Switch Block controls the operational modes of the MT8940 DPLL device

that is used to generate the backplane clock. The various modes of the device are

selected by DIP switch settings. Access to the enable inputs for the various clock

outputs is also provided through these switches.

2.5

Clock DPLL

The MT8940 T1/CEPT Digital Trunk DPLL can provide a number of different clocks

with different methods of synchronization, depending upon its mode setting, which

can be used to drive the backplane interface of the T1XCs. The device can output

1.544 MHz, 2.048 MHz, and 4.096 MHz clocks in true or complement format. The

DPLL can be allowed to free-run or it can be synchronized to the receive frame

pulses of either T1XC. PLL control is accomplished with the DIP switches

connected to the inputs.

2.6

Oscillators

Up to four oscillators can be used on the T1XC EVBD daughterboard depending

upon the choice of configuration. The T1XC devices require a 37.056 MHz clock if

all of the device's features are to be utilized. Although two oscillator sockets are

provided, only a single oscillator is necessary if two T1XC devices are used. The

insertion of a jumper (J25) will join the two T1XC XCLK inputs together to allow the

single clock to drive both devices. If an E1XC device is used in place of one of the

T1XC devices then the jumper must be removed to isolate each clock line and a

49.152 MHz oscillator is used to drive the E1XC XCLK input.

The MT8940 DPLL device requires two oscillators to drive internal DPLLs, one at

12.355 MHz, and the other at 16.384 MHz. If the MT8940 is removed from the

daughterboard, then these oscillators can be replaced with ones directly compatible

with the backplane rate. Each oscillator output is directly accessible at header pins,

allowing connections to be made by connecting jumpers to the T1XC devices.

PM4541 Datasheet(PDF) 6 Page - PMC-Sierra, Inc

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