MPC9772

MOTOROLA

10

TIMING SOLUTIONS

SYNC Output Description

The MPC9772 has a system synchronization pulse output

QSYNC. In configurations with the output frequency

relationships are not integer multiples of each other QSYNC

provides a signal for system synchronization purposes. The

MPC9772 monitors the relationship between the A bank and

the B bank of outputs. The QSYNC output is asserted (logic

low) one period in duration and one period prior to the

coincident rising edges of the QA and QC outputs. The duration

and the placement of the pulse is dependent QA and QC output

frequencies: the QSYNC pulse width is equal to the period of

the higher of the QA and QC output frequencies. Figure 6

shows various waveforms for the QSYNC output. The QSYNC

output is defined for all possible combinations of the bank A and

bank C outputs.

1:1 Mode

QA

QC

QSYNC

2:1 Mode

QC(

÷2)

QA(

÷6)

QSYNC

3:1 Mode

QA

QC

QSYNC

QA(

÷4)

QC(

÷6)

QSYNC

3:2 Mode

QC(

÷2)

QA(

÷8)

QSYNC

4:1 Mode

QA(

÷6)

QC(

÷8)

QSYNC

4:3 Mode

QA(

÷12)

QC(

÷2)

QSYNC

6:1 Mode

Figure 6. QSYNC Timing Diagram