Preliminary Data Sheet #: TM055

Page 10 of 24

Rev: P00

Date: 5/17/04

© Copyright 2004 The Connor-Winfield Corp.

Reference Qualification

Reference qualification requires that a reference be both present and within the required frequency limits for a minimum of 10

seconds. Any time a reference is disqualified due to a loss of signal or frequency offset, the 10 second window will start over. The

active reference can also be disqualified if there is a phase-time movement on the input that is greater than the allowable movement

for jitter tolerance and frequency hold-in range. If active reference is disqualified due to a faster than allowed phase-time change

(phase hit), the module will immediately go into Hold Over (or Free Run if Hold Over is not valid) for a minimum of 2ms, after which

the module will act as though the reference was disqualified due to a LOR or off-frequency condition.

SPI Timing and Operation

The SPI port is set up for 8 bit communication. All address bytes are 8 bits in length, reads return 8 bits and writes require 8 bits.

The MSB of each address byte is the read/write bit. The lower 7 bits are the lowest 7 bits of the specified address. For example, a

read from address 01h would require the byte 1000 0001b to be sent to the module, MSB first.

Format for Address Byte

R/W: Read=1/Write=0

Bit 6 - Bit 0: Address Information

Send A7 First

Format for Data Byte

Bit 7 - Bit 0: Data Information

Receive/Send D7 First

Table 9

A7

A6

A5

A4

A3

A2

A1

A0

R/W

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit0

Table 10

D7

D6

D5

D4

D3

D2

D1

D0

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Frequency

Rejection

Limit

Frequency

Qualification

Limit

Frequency

Qualification

Limit

Frequency

Rejection

Limit

Nominal

Reference

is not

qualified

Reference

is not

qualified

Reference is qualified

Reference

may or may

not be

qualified

(3ppm minimum)

Reference

may or may

not be

qualified

(3ppm minimum)

Reference Frequency Qualification Test

Figure 6