W134M/W134S
Table 4. Bypass and Test Mode Selection
Mode
Normal
Output Test (OE)
Bypass
Test
S0
0
0
1
1
S1
0
1
0
1
Bypclk
(int.)
Gnd
–
PLLclk
Refclk
Clk
PAclk
Hi-Z
PLLclk
Refclk
ClkB
PAclkB
Hi-Z
PLLclkB
RefclkB
Table of Frequencies and Gear Ratios
Table 6
shows several supported Pclk and Busclk
frequencies, the corresponding A and B dividers required in
the DRCG PLL, and the corresponding M and N dividers in the
gear ratio logic. The column Ratio gives the Gear Ratio as
defined Pclk/Synclk (same as M and N). The column F@PD
gives the divided down frequency (in MHz) at the Phase
Detector, where F@PD = Pclk/M = Synclk/N.
State Transitions
The clock source has three fundamental operating states.
Figure 4
shows the state diagram with each transition labelled
A through H. Note that the clock source output may NOT be
glitch-free during state transitions.
Upon powering up the device, the device can enter any state,
depending on the settings of the control signals, PwrDnB and
StopB.
In Power-down mode, the clock source is powered down with
the control signal, PwrDnB, equal to 0. The control signals S0
and S1 must be stable before power is applied to the device,
and can only be changed in Power-down mode (PwrDnB = 0).
The reference inputs, V
DDR
and V
DDPD
, may remain on or may
be grounded during the Power-down mode.
A
8
6
8
4
6
B
1
1
1
1
1
M
2
8
4
4
8
N
2
6
4
2
6
Ratio
1.0
1.33
1.0
2.0
1.33
F@PD
33
12.5
25
33
16.7
Table 5
shows the logic for selecting the Power-down mode,
using the PwrDnB input signal. PwrDnB is active LOW
(enabled when 0). When PwrDnB is disabled, the DRCG is in
its normal mode. When PwrDnB is enabled, the DRCG is put
into a powered-off state, and the Clk and ClkB outputs are
three-stated.
Table 5. Power-down Mode Selection
Mode
Normal
Power-down
PwrDnB
1
0
Clk
PAclk
GND
ClkB
PAclkB
GND
Table 6. Examples of Frequencies, Dividers, and Gear Ratios
Pclk
67
100
100
133
133
Refclk
33
50
50
67
67
Busclk
267
300
400
267
400
Synclk
67
75
100
67
100
VDD Turn-On
M
L
Test
K
VDD Turn-On
N
B
Power-Down
VDD Turn-On
J
G
Normal
A
D
C
F
E
Clk Stop
VDD Turn-On
H
Figure 4. Clock Source State Diagram
The control signals Mult0 and Mult1 can be used in two ways.
If they are changed during Power-down mode, then the
Power-down transition timings determine the settling time of
the DRCG. However, the Mult0 and Mult1 control signals can
also be changed during Normal mode. When the Mult control
signals are “hot-swapped” in this manner, the Mult transition
timings determine the settling time of the DRCG.
In Normal mode, the clock source is on, and the output is
enabled.
Table 7
lists the control signals for each state.
Table 7. Control Signals for Clock Source States
State
Power-down
Clock Stop
Normal
PwrDnB
0
1
1
StopB
X
0
1
Clock
Source
OFF
ON
ON
Output
Buffer
Ground
Disabled
Enabled
Figure 5
shows the timing diagrams for the various transitions
between states, and
Table 8
specifies the latencies of each
state transition. Note that these transition latencies assume
the following.
Refclk input has settled and meets specification shown in
Table
.
Mult0, Mult1, S0 and S1 control signals are stable.
Document #: 38-07426 Rev. *B
Page 5 of 12
CYPRESS [ CYPRESS SEMICONDUCTOR ]
