Cypress Semiconductor CY7B9911V Технический паспорт - Страница 3

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Block Diagram Description

Phase Frequency Detector and Filter
The Phase Frequency Detector and Filter blocks accept inputs
from the Reference Frequency (REF) input and the Feedback
(FB) input. They generate correction information to control the
frequency of the Voltage Controlled Oscillator (VCO). These
blocks, along with the VCO, form a Phase Locked Loop (PLL)
that tracks the incoming REF signal.
VCO and Time Unit Generator
The VCO accepts analog control inputs from the PLL filter block.
It generates a frequency used by the time unit generator to
create discrete time units that are selected in the skew select
matrix. The operational range of the VCO is determined by the
FS control pin. The time unit (t
frequency of the device and the level of the FS pin as shown in
Table
1.
Table 1. Frequency Range Select and t
f
(MHz)
NOM
=
t
[2, 3]
U
FS
Min
Max
where N =
LOW
15
30
MID
25
50
HIGH
40
110
Notes
1. For all three-state inputs, HIGH indicates a connection to V
circuitry holds an unconnected input to V
2. The level to be set on FS is determined by the "normal" operating frequency (f
appears at 1Q0 and the other outputs when they are operated in their undivided modes (see
when the output connected to FB is undivided. The frequency of the REF and FB inputs is f
using a divided output as the FB input.
3. When the FS pin is selected HIGH, the REF input must not transition upon power up until V
Document Number: 38-07408 Rev. *D
) is determined by the operating
U
[1]
Calculation
U
Approximate
1
----------------------- -
×
Frequency (MHz) At
f
N
NOM
Which t
= 1.0 ns
U
44
22.7
26
38.5
16
62.5
, LOW indicates a connection to GND, and MID indicates an open connection. Internal termination
CC
/2.
CC
Skew Select Matrix
The skew select matrix is comprised of four independent
sections. Each section has two low skew, high fanout drivers
(xQ0, xQ1), and two corresponding three level function select
(xF0, xF1) inputs.
Table 2
functions for each section as determined by the function select
inputs. All times are measured with respect to the REF input
assuming that the output connected to the FB input has 0t
selected.
Table 2. Programmable Skew Configurations
Function Selects
1F1, 2F1,
1F0, 2F0,
1Q0, 1Q1,
3F1, 4F1
3F0, 4F0
2Q0, 2Q1
LOW
LOW
LOW
MID
LOW
HIGH
MID
LOW
MID
MID
MID
HIGH
HIGH
LOW
HIGH
MID
HIGH
HIGH
) of the V
and Time Unit Generator (see). Nominal frequency (f
NOM
CO
Table
2). The frequency appearing at the REF and FB inputs is f
/2 or f
/4 when the part is configured for a frequency multiplication
NOM
NOM
has reached 2.8V.
CC
CY7B9911V
3.3V RoboClock+™
shows the nine possible output
[1]
Output Functions
3Q0, 3Q1
4Q0, 4Q1
–4t
Divide by 2 Divide by 2
U
–3t
–6t
–6t
U
U
U
–2t
–4t
–4t
U
U
U
–1t
–2t
–2t
U
U
U
0t
0t
0t
U
U
U
+1t
+2t
+2t
U
U
U
+2t
+4t
+4t
U
U
U
+3t
+6t
+6t
U
U
U
+4t
Divide by 4
Inverted
U
) always
NOM
Page 3 of 14
U
NOM
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