REVISION 8 3/16/16 9 ©2016 INTEGRATED DEVICE TECHNOLOGY, INC.
MPC9772 DATA SHEET
MPC9772 Individual Output Disable
(Clock Stop) Circuitry
The individual clock stop (output enable) control of the
MPC9772 allows designers, under software control, to
implement power management into the clock distribution
design. A simple serial interface and a clock stop control logic
provides a mechanism through which the MPC9772 clock
outputs can be individually stopped in the logic ‘0’ state: The
clock stop mechanism allows serial loading of a 12-bit serial
input register. This register contains one programmable clock
stop bit for 12 of the 14 output clocks. The QC0 and QFB
outputs cannot be stopped (disabled) with the serial port.
The user can program an output clock to stop (disable) by
writing logic ‘0’ to the respective stop enable bit. Likewise, the
user may programmably enable an output clock by writing
logic ‘1’ to the respective enable bit. The clock stop logic
enables or disables clock outputs during the time when the
output would be in normally in logic low state, eliminating the
possibility of short or ‘runt’ clock pulses.
The user can write to the serial input register through the
STOP_DATA input by supplying a logic ‘0’ start bit followed
serially by 12 NRZ disable/enable bits. The period of each
STOP_DATA bit equals the period of the free—running
STOP_CLK signal. The STOP_DATA serial transmission
should be timed so the MPC9772 can sample each
STOP_DATA bit with the rising edge of the free—running
STOP_CLK signal. (See Figure 5.)
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.
Figure 3. Example Configuration
Figure 4. Example Configuration
MPC9772
f
ref
= 33.3 MHz
33.3 MHz
100 MHz
33.3 MHz (Feedback)
200 MHz
CCLK0
VCO_SEL
FSEL_A[1:0]
FSEL_B[1:0]
FSEL_C[1:0]
FSEL_FB[2:0]
QA[3:0]
QB[3:0]
QC[3:0]
QFB
CCLK1
CCLK_SEL
FB_IN
1
11
00
00
101
MPC9772 example configuration (feedback of QFB = 33.3 MHz,
f
VCO
=400 MHz, VCO_SEL=1, M=12, N
A
=12, N
B
=4, N
C
=2).
Frequency Range
T
A
= 0°C to +70°C T
A
= –40°C to +85°C
Input 16.6 – 40 MHz 16.6 – 38.33 MHz
QA Outputs 16.6 – 40 MHz 16.6 – 38.33 MHz
QA Outputs 50 – 120 MHz 50 – 115 MHz
QC Outputs 100 – 240 MHz 100 – 230 MHz
MPC9772
f
ref
= 25 MHz
62.5 MHz
62.5 MHz
25 MHz (Feedback)
125 MHz
CCLK0
VCO_SEL
FSEL_A[1:0]
FSEL_B[1:0]
FSEL_C[1:0]
FSEL_FB[2:0]
QA[3:0]
QB[3:0]
QC[3:0]
QFB
CCLK1
CCLK_SEL
FB_IN
1
00
00
00
011
MPC9772 example configuration (feedback of QFB = 25 MHz,
f
VCO
=250 MHz, VCO_SEL=1, M=10, N
A
=4, N
B
=4, N
C
=2).
Frequency Range
T
A
= 0°C to +70°C T
A
= –40°C to +85°C
Input 20 – 48 MHz 20 – 46 MHz
QA Outputs 50 – 120 MHz 50 – 115 MHz
QA Outputs 50 – 120 MHz 50 – 115 MHz
QC Outputs 100 – 240 MHz 100 – 230 MHz
Figure 5. Clock Stop Circuit Programming
STOP_CLK
STOP_DATA
START QA0 QA1 QA2 QA3 QB0 QB1 QB2 QB3 QC1 QC2 QC3 QSYNC
