Cypress CY7C9925LFXC 3.3v/2.5v programmable skew clock buffer Datasheet

CY7C9925
PRELIMINARY
3.3V/2.5V Programmable Skew Clock Buffer
Features
Functional Description
• All output pair skew <100 ps (typical)
The CY7C9925 RoboClock is 200-MHz Low-voltage Programmable Skew Clock Buffer that offers user-selectable control
over system clock functions. This multiple-output clock driver
provides the system integrator with functions necessary to
optimize the timing of high-performance computer systems.
Eight individual drivers, arranged as four pairs of user-controllable outputs, can each drive terminated transmission lines
with impedances as low as 50Ω while delivering minimal and
specified output skews and full-swing logic levels (LVTTL).
• Input Frequency Range: 3.75 MHz to 200 MHz
• Output Frequency Range: 3.75 MHz to 200 MHz
• User-selectable output functions
— Selectable skew to 18 ns
— Inverted and non-inverted
— Operation at 1⁄2 and 1⁄4 input frequency
— Operation at 2x and 4x input frequency (input as low
as 3.75 MHz)
• Zero input-to-output delay
• 3.3V Core power supply
• Split 2.5V or 3.3V Output power supplies
• ± 2.5% Output Duty Cycle Distortion for 3.3V Output
• LVTTL outputs drive 50Ω terminated lines
Each output can be hardwired to one of nine delay or function
configurations. Delay increments of 0.32 to 1.6 ns are determined by the operating frequency with outputs able to skew up
to ±6 time units from their nominal “zero” skew position. The
completely integrated PLL allows external load and transmission line delay effects to be canceled. When this “zero
delay” capability of the LVPSCB is combined with the
selectable output skew functions, the user can create
output-to-output delays of up to ±12 time units.
Divide-by-two and divide-by-four output functions are provided
for additional flexibility in designing complex clock systems.
When combined with the internal PLL, these divide functions
allow distribution of a low-frequency clock that can be multiplied by two or four at the clock destination. This facility
minimizes clock distribution difficulty while allowing maximum
system clock speed and flexibility.
• Low operating current
• 32-pin QFN package
• Jitter < 100ps peak-to-peak (< 15 ps RMS)
Block Diagram
Pin Configuration
4
21
VCCN1
VCCN4
5
20
1Q0
4Q1
6
19
1Q1
4Q0
7
18
GND
GND
8
17
GND
CY7C9925
2Q1
1F0
2Q0
2Q0
GND
10 11 12 13 14 15 16
2Q1
9
VCCN2
3Q1
MATRIX
1Q0
1F0
1F1
Cypress Semiconductor Corporation
Document #: 38-07688 Rev. **
2F0
VCCQ
FB
2F0
2F1
2F1
23
22
1F1
4F1
2
3
3Q0
SELECT
TEST
4F0
VCCN3
SKEW
GND
32 31 30 29 28 27 26 25
24
GND
3F0
3F1
4Q1
REF
1
4Q0
SELECT
INPUTS
(THREE
LEVEL)
VCCQ
3F1
FS
4F0
4F1
FS
VCO AND
TIME UNIT
GENERATOR
3Q0
REF
FILTER
3Q1
PHASE
FREQ
DET
FB
3F0
TEST
1Q1
•
3901 North First Street
•
San Jose, CA 95134
•
408-943-2600
Revised June 25, 2004
CY7C9925
PRELIMINARY
Pin Definitions
Pin No.
Name
I/O
Type
Description
29
Ref
Input
LVTTL/LVCMOS
Reference Clock Input
13
FB
Input
LVTTL
Feedback Clock Input
31
FS
Input
Three-level
Three Level Frequency Range Select
1F0, 1F1
Input
Three-level
Three level function select for 1Q0,1Q1
25,26
2F0, 2F1
Input
Three-level
Three level function select for 2Q0,2Q1
32,1
3F0, 3F1
Input
Three-level
Three level function select for 3Q0,3Q1
2, 3
4F0, 4F1
Input
Three-level
Three level function select for 4Q0,4Q1
27
Test
Input
Three-level
Three level select for test modes
22,23
19,20
1Q0, 1Q1 Output
LVTTL
Output Pair
15,16
2Q0, 2Q1 Output
LVTTL
Output Pair
10,11
3Q0, 3Q1 Output
LVTTL
Output Pair
6,7
4Q0, 4Q1 Output
LVTTL
Output Pair
21
VCCN1
Power
POWER
3.3V or 2.5V Power Supply for output pair 1Q0 and 1Q1.
14
VCCN2
Power
POWER
3.3V or 2.5V Power Supply for output pair 2Q0 and 2Q1.
12
VCCN3
Power
POWER
3.3V or 2.5V Power Supply for output pair 3Q0 and 3Q1.
5
VCCN4
Power
POWER
3.3V or 2.5V Power Supply for output pair 4Q0 and 4Q1.
4,30
VCCQ
8,9,17,18,24,28 GND
Power
POWER
3.3V Core Power
Ground
POWER
Ground
Block Diagram Description
Phase Frequency Detector and Filter
These two blocks accept inputs from the Reference Frequency
(REF) input and the Feedback (FB) input and 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 and generates a frequency that is 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 (tU) is determined
by the operating frequency of the device and the level of the
FS pin as shown in Table 1.
Table 1. Frequency Range Select and tU Calculation[1]
fNOM (MHz)
FS[2]
LOW
Min.
Max.
where N =
Approximate
Frequency (MHz)
At Which tU = 1.0
ns
15
30
44
22.7
1
t U = -----------------------f NOM × N
MID
25
50
26
38.5
HIGH
40
200
16
62.5
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 below shows the nine possible
output 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
0tU selected.
Notes:
1. For all three-state inputs, HIGH indicates a connection to VCC, LOW indicates a connection to GND, and MID indicates an open connection. Internal termination
circuitry holds an unconnected input to VCC/2.
2. The level to be set on FS is determined by the “normal” operating frequency (fNOM) of the VCO and Time Unit Generator (see Logic Block Diagram). Nominal
frequency (fNOM) always appears at 1Q0 and the other outputs when they are operated in their undivided modes (see Table 2). The frequency appearing at the
REF and FB inputs will be fNOM when the output connected to FB is undivided. The frequency of the REF and FB inputs will be fNOM/2 or fNOM/4 when the part
is configured for a frequency multiplication by using a divided output as the FB input.
Document #: 38-07688 Rev. **
Page 2 of 12
CY7C9925
PRELIMINARY
Table 2. Programmable Skew Configurations[1]
Output Functions
3Q0, 3Q1
4Q0, 4Q1
–2tU
–2tU
0tU
0tU
0tU
+4tU
HIGH
MID
+3tU
+6tU
+6tU
HIGH
HIGH
+4tU
Divide by 4
Inverted
t 0 – 2t U
+2tU
+4tU
t 0 – 3t U
+2tU
+2tU
t 0 – 4t U
+1tU
LOW
t 0 – 5t U
HIGH
HIGH
t 0 – 6t U
MID
U
–1tU
MID
t 0 +6t
LOW
MID
U
MID
t 0 +5t
–4tU
U
–6tU
–4tU
t 0 +4t
–6tU
–2tU
U
–3tU
HIGH
t 0 +3t
MID
U
LOW
LOW
t 0 +2t
Divide by 2 Divide by 2
U
–4tU
t 0 +1t
LOW
t0
LOW
t 0 – 1t U
Function Selects
1F1, 2F1, 1F0, 2F0, 1Q0, 1Q1,
3F1, 4F1 3F0, 4F0 2Q0, 2Q1
FBInput
REFInput
1Fx
2Fx
3Fx
4Fx
(N/A)
LM
– 6tU
LL
LH
– 4tU
LM
(N/A)
– 3tU
LH
ML
– 2tU
ML
(N/A)
– 1tU
MM
MM
MH
(N/A)
+1tU
HL
MH
+2tU
HM
(N/A)
+3tU
HH
HL
+4tU
0tU
(N/A)
HM
(N/A)
LL/HH
DIVIDED
(N/A)
HH
INVERT
+6tU
Figure 1. Typical Outputs with FB Connected to a Zero-Skew Output[3]
Note:
3. FB connected to an output selected for “zero” skew (i.e., xF1 = xF0 = MID).
Document #: 38-07688 Rev. **
Page 3 of 12
CY7C9925
PRELIMINARY
Test Mode
The TEST input is a three-level input. In normal system
operation, this pin is connected to ground, allowing the
CY7C9925 to operate as explained briefly above (for testing
purposes, any of the three-level inputs can have a removable
jumper to ground, or be tied LOW through a 100Ω resistor.
This will allow an external tester to change the state of these
pins.)If the TEST input is forced to its MID or HIGH state, the
device will operate with its internal phase locked loop disconnected, and input levels supplied to REF will directly control all
outputs. Relative output to output functions are the same as in
normal mode.
In contrast with normal operation (TEST tied LOW). All outputs
will function based only on the connection of their own function
select inputs (xF0 and xF1) and the waveform characteristics
of the REF input.
Operational Mode Descriptions
REF
SYSTEM
CLOCK
LOAD
Z0
L1
FB
REF
FS
LOAD
4F0
4F1
4Q0
4Q1
3F0
3F1
2F0
2F1
3Q0
3Q1
1F0
1F1
1Q0
1Q1
L2
Z0
LOAD
L3
2Q0
2Q1
Z0
L4
LOAD
TEST
Z0
LENGTH L1 = L2 = L3 = L4
Figure 2. Zero-Skew and/or Zero-Delay Clock Driver
Figure 2 shows the LVPSCB configured as a zero-skew clock
buffer. In this mode the CY7C9925 can be used as the basis
for a low-skew clock distribution tree. When all of the function
select inputs (xF0, xF1) are left open, the outputs are aligned
and may each drive a terminated transmission line to an
independent load. The FB input can be tied to any output in
this configuration and the operating frequency range is
selected with the FS pin. The low-skew specification, coupled
with the ability to drive terminated transmission lines (with
impedances as low as 50Ω), allows efficient printed circuit
board design.
REF
SYSTEM
CLOCK
FB
REF
FS
4F0
4F1
LOAD
L1
4Q0
4Q1
3F0
3F1
2F0
2F1
3Q0
3Q1
1F0
1F1
1Q0
1Q1
2Q0
2Q1
Z0
LOAD
L2
Z0
LOAD
L3
Z0
L4
LOAD
TEST
LENGTH L1 = L2
L3 < L2 by 6 inches
L4 > L2 by 6 inches
Z0
Figure 3. Programmable-Skew Clock Driver
Figure 3 shows a configuration to equalize skew between
metal traces of different lengths. In addition to low skew
between outputs, the LVPSCB can be programmed to stagger
the timing of its outputs. The four groups of output pairs can
Document #: 38-07688 Rev. **
each be programmed to different output timing. Skew timing
can be adjusted over a wide range in small increments with the
appropriate strapping of the function select pins. In this configuration the 4Q0 output is fed back to FB and configured for
Page 4 of 12
CY7C9925
PRELIMINARY
zero skew. The other three pairs of outputs are programmed
to yield different skews relative to the feedback. By advancing
the clock signal on the longer traces or retarding the clock
signal on shorter traces, all loads can receive the clock pulse
at the same time.
In this illustration the FB input is connected to an output with
0-ns skew (xF1, xF0 = MID) selected. The internal PLL
synchronizes the FB and REF inputs and aligns their rising
edges to insure that all outputs have precise phase alignment.
Clock skews can be advanced by ±6 time units (tU) when using
an output selected for zero skew as the feedback. A wider range of
delays is possible if the output connected to FB is also skewed.
Since “Zero Skew”, +tU, and –tU are defined relative to output
groups, and since the PLL aligns the rising edges of REF and FB,
it is possible to create wider output skews by proper selection of the
xFn inputs. For example a +10 tU between REF and 3Qx can be
achieved by connecting 1Q0 to FB and setting 1F0 = 1F1 = GND,
3F0 = MID, and 3F1 = High. (Since FB aligns at –4 tU and 3Qx
skews to +6 tU, a total of +10 tU skew is realized.) Many other configurations can be realized by skewing both the output used as the FB
input and skewing the other outputs.
REF
FB
REF
FS
4F0
4F1
4Q0
4Q1
3F0
3F1
3Q0
3Q1
2F0
2F1
2Q0
2Q1
1F0
1F1
1Q0
1Q1
TEST
Figure 4. Inverted Output Connections
Figure 4 shows an example of the invert function of the
LVPSCB. In this example the 4Q0 output used as the FB input
is programmed for invert (4F0 = 4F1 = HIGH) while the other
three pairs of outputs are programmed for zero skew. When
4F0 and 4F1 are tied HIGH, 4Q0 and 4Q1 become inverted
zero phase outputs. The PLL aligns the rising edge of the FB
input with the rising edge of the REF. This causes the 1Q, 2Q,
and 3Q outputs to become the “inverted” outputs with respect
to the REF input. By selecting which output is connect to FB,
it is possible to have 2 inverted and 6 non-inverted outputs or
6 inverted and 2 non-inverted outputs. The correct configuration would be determined by the need for more (or fewer)
inverted outputs. 1Q, 2Q, and 3Q outputs can also be skewed
to compensate for varying trace delays independent of
inversion on 4Q.
Document #: 38-07688 Rev. **
REF
20 MHz
FB
REF
FS
4F0
4F1
3F0
3F1
2F0
2F1
1F0
1F1
TEST
40 MHz
4Q0
4Q1
3Q0
3Q1
2Q0
2Q1
1Q0
1Q1
20 MHz
80 MHz
Figure 5. Frequency Multiplier with Skew Connections
Figure 5 illustrates the LVPSCB configured as a clock multiplier. The 3Q0 output is programmed to divide by four and is
fed back to FB. This causes the PLL to increase its frequency
until the 3Q0 and 3Q1 outputs are locked at 20 MHz while the
1Qx and 2Qx outputs run at 80 MHz. The 4Q0 and 4Q1
outputs are programmed to divide by two, which results in a
40-MHz waveform at these outputs. Note that the 20- and
40-MHz clocks fall simultaneously and are out of phase on
their rising edge. This will allow the designer to use the rising
edges of the 1⁄2 frequency and 1⁄4 frequency outputs without
concern for rising-edge skew. The 2Q0, 2Q1, 1Q0, and 1Q1
outputs run at 80 MHz and are skewed by programming their
select inputs accordingly. Note that the FS pin is wired for
80-MHz operation because that is the frequency of the fastest
output.
REF
20 MHz
FB
REF
FS
4F0
4F1
4Q0
4Q1
10 MHz
3F0
3F1
2F0
2F1
3Q0
3Q1
5 MHz
1F0
1F1
TEST
1Q0
1Q1
2Q0
2Q1
20 MHz
Figure 6. Frequency Divider Connections
Figure 6 demonstrates the LVPSCB in a clock divider application. 2Q0 is fed back to the FB input and programmed for
zero skew. 3Qx is programmed to divide by four. 4Qx is
programmed to divide by two. Note that the falling edges of the
4Qx and 3Qx outputs are aligned. This allows use of the rising
edges of the 1⁄2 frequency and 1⁄4 frequency without concern
for skew mismatch. The 1Qx outputs are programmed to zero
skew and are aligned with the 2Qx outputs. In this example,
the FS input is grounded to configure the device in the 15- to
Page 5 of 12
CY7C9925
PRELIMINARY
30-MHz range since the highest frequency output is running at
20 MHz.
Figure 7 shows some of the functions that are selectable on
the 3Qx and 4Qx outputs. These include inverted outputs and
outputs that offer divide-by-2 and divide-by-4 timing. An
inverted output allows the system designer to clock different
subsystems on opposite edges, without suffering from the
pulse asymmetry typical of non-ideal loading. This function
allows the two subsystems to each be clocked 180 degrees
out of phase, but still to be aligned within the skew spec.
The divided outputs offer a zero-delay divider for portions of
the system that need the clock to be divided by either two or
four, and still remain within a narrow skew of the “1X” clock.
Without this feature, an external divider would need to be
added, and the propagation delay of the divider would add to
the skew between the different clock signals.
These divided outputs, coupled with the Phase Locked Loop,
allow the LVPSCB to multiply the clock rate at the REF input
by either two or four. This mode will enable the designer to
distribute a low-frequency clock between various portions of
the system, and then locally multiply the clock rate to a more
suitable frequency, while still maintaining the low-skew characteristics of the clock driver. The LVPSCB can perform all of the
functions described above at the same time. It can multiply by
two and four or divide by two (and four) at the same time that
it is shifting its outputs over a wide range or maintaining zero
skew between selected outputs.
REF
LOAD
Z0
27.5-MHz
DISTRIBUTION
CLOCK
110-MHz
INVERTED
FB
REF
FS
4F0
4F1
3F0
3F1
2F0
2F1
1F0
1F1
TEST
LOAD
4Q0
4Q1
3Q0
3Q1
2Q0
2Q1
1Q0
1Q1
27.5-MHz
Z0
LOAD
110-MHz
ZERO SKEW
110-MHz
SKEWED –2.273 ns (–4tU)
Z0
LOAD
Z0
Figure 7. Multi-Function Clock Driver
LOAD
REF
Z0
L1
FB
SYSTEM
CLOCK
REF
FS
4F0
4F1
3F0
3F1
2F0
2F1
1F0
1F1
LOAD
L2
4Q0
4Q1
3Q0
3Q1
Z0
LOAD
L3
2Q0
2Q1
1Q0
1Q1
Z0
L4
TEST
Z0
FB
REF
FS
4F0
4F1
3F0
3F1
2F0
2F1
1F0
1F1
TEST
4Q0
4Q1
3Q0
3Q1
2Q0
2Q1
1Q0
1Q1
LOAD
LOAD
Figure 8. Board-to-Board Clock Distribution
Figure 8 shows the CY7C9925 connected in series to
construct a zero-skew clock distribution tree between boards.
Delays of the downstream clock buffers can be programmed
to compensate for the wire length (i.e., select negative skew
equal to the wire delay) necessary to connect them to the
Document #: 38-07688 Rev. **
master clock source, approximating a zero-delay clock tree.
Cascaded clock buffers will accumulate low-frequency jitter
because of the non-ideal filtering characteristics of the PLL
filter. It is recommended that not more than two clock buffers
be connected in series.
Page 6 of 12
CY7C9925
PRELIMINARY
Absolute Maximum Conditions
Parameter
Description
Condition
Min.
Max.
Unit
VDD
Supply Voltage
Nonfunctional
–0.5
4.6
VDC
VIN
Input Voltage REF
Relative to VCC
–0.5
4.6
VDC
–0.5
VDD + 0.5
VDC
VIN
Input Voltage Except REF
Relative to VCC
LUI
Latch-up Immunity
Functional
TS
Temperature, Storage
Nonfunctional
TA
Temperature, Operating Ambient
Commercial Temperature
TA
Temperature, Operating Ambient
Industrial Temperature
TJ
Junction Temperature
Industrial Temperature
300
mA
–65
+125
°C
0
+70
°C
–40
+85
°C
125
°C
ØJc
Dissipation, Junction to Case
Functional
TBD
°C/W
ØJa
Dissipation, Junction to Ambient
Functional
TBD
°C/W
ESDh
ESD Protection (Human Body Model)
MSL
Moisture Sensitivity Level
GATES
Total Functional Gate Count
UL–94
Flammability Rating
FIT
Failure in Time
Manufacturing test
TPU
Power-up time for all VDDs to reach
minimum specified voltage (power ramps
must be monotonic)
CIN
Input Capacitance[4]
TA = 25°C, f = 1 MHz, VCC = 3.3V
ZOUT
Output Impedance
Low to High (Rising edge)
27
Ω
High to Low (Falling edge)
7
Ω
Electrical Characteristics Over the Operating
Parameter
Description
2000
V
MSL – 1
Class
Assembled Die
TBD
Each
@ 1/8 in.
V–0
class
10
0.05
–
ppm
500
ms
10
pF
Range [5]
Test Conditions
Min.
Max.
VCCQ
Core Power Supply
@3.3V ± 10%
2.97
3.63
V
VCCN[1:4]
Output Buffer Power Supply
@3.3V ± 10%
2.97
3.63
V
@2.5V ± 5%
VOH
Output HIGH Voltage
VOL
Output LOW Voltage
–
0.4
VIH
Input HIGH Voltage
(REF and FB inputs only)[6]
2.0
VCC
V
VIL
Input LOW Voltage
(REF and FB inputs only)[6]
–0.5
0.8
V
VIHH
Three-Level Input HIGH
Voltage (Test, FS, xFn)[7]
Min. ≤ VCC ≤ Max.
0.87 * VCC
VCC
V
VIMM
Three-Level Input MID
Voltage (Test, FS, xFn)[7]
Min. ≤ VCC ≤ Max.
0.47 * VCC
0.53 * VCC
V
VILL
Three-Level Input LOW
Voltage (Test, FS, xFn)[7]
Min. ≤ VCC ≤ Max.
0.0
0.13 * VCC
V
IIH
Input HIGH Leakage Current
(REF and FB inputs only)
VCC = Max., VIN = Max.
–
10
µA
2.375
2.625
V
VCC = Min., IOH = –20 mA (3.3V)
2.4
–
V
VCC = Min., IOH = –15 mA (2.5V)
1.8
–
–
0.45
VCC = Min., IOL = 36 mA (3.3V)
VCC = Min., IOL = 20 mA (2.5V)
V
Notes:
4. Applies to REF and FB inputs only. Tested initially and after any design or process changes that may affect these parameters.
5. See the last page of this specification for Group A subgroup testing information.
6. VIH and VIL for FB inputs guaranteed by statistical correlation. Tested initially and after any design or process changes that may affect this parameters.
Document #: 38-07688 Rev. **
Page 7 of 12
CY7C9925
PRELIMINARY
Electrical Characteristics Over the Operating Range (continued)[5]
Parameter
Description
Test Conditions
Min.
Max.
–10
–
µA
–
200
µA
VIN = VCC/2
–50
50
µA
Input LOW Current
(Test, FS, xFn)
VIN = GND
–
–200
µA
IOS
Short Circuit Current[8]
VCC = MAX, VOUT = GND (25° only)
–
–200
mA
ICCQ
Operating Current Used by
Internal Circuitry
VCCN = VCCQ = Max., All Input
Selects Open
–
90
mA
–
100
ICCN
Output Buffer Current per
Output Pair[9]
VCCN = VCCQ = Max., IOUT = 0 mA
Input Selects Open, fMAX
–
14
mA
PD
Power Dissipation per
Output Pair[10]
VCCN = VCCQ = Max., IOUT = 0 mA
Input Selects Open, fMAX
–
78
mW
IIL
Input LOW Leakage Current
(REF and FB inputs only)
VCC = Max., VIN = 0.4V
IIHH
Input HIGH Current
(Test, FS, xFn)
VIN = VCC
IIMM
Input MID Current
(Test, FS, xFn)
IILL
AC Test Loads and Waveforms
VCC
R1
CL
R2
3.0V
2.0V
Vth =1.5V
0.8V
0.0V
R1=100
R2=100
CL = 30 pF
(Includes fixture and probe capacitance)
2.0V
Vth =1.5V
0.8V
≤1ns
≤1ns
TTL AC Test Load
TTL Input Test Waveform
AC Input Specifications
Parameter
Description
Condition
Min.
Max.
Unit
TR,TF
Input Rise/Fall Edge Rate
0.8V – 2.0V
–
10
ns/V
TPWC
Input Clock Pulse
HIGH or LOW
2
–
ns
TDCIN
Input Duty Cycle
PLL
10
90
%
Test Mode
30
70
FS=LOW
3.75
30
FS=MID
6.25
50
10
200[11]
FREF
Reference Input Frequency
FS=HIGH
MHz
Notes:
7. These inputs are normally wired to VCC, GND, or left unconnected (actual threshold voltages vary as a percentage of VCC). Internal termination resistors hold
unconnected inputs at VCC/2. If these inputs are switched, the function and timing of the outputs may glitch and the PLL may require an additional tLOCK time
before all data sheet limits are achieved.
8. CY7C9925 should be tested one output at a time, output shorted for less than one second, less than 10% duty cycle. Room temperature only.
9. Total output current per output pair can be approximated by the following expression that includes device current plus load current:
CY7C9925:ICCN = [(4 + 0.11F) + [[((835 –3F)/Z) + (.0022FC)]N] x 1.1
Where
F = frequency in MHz
C = capacitive load in pF
Z = line impedance in ohms
N = number of loaded outputs; 0, 1, or 2
FC = F ∗ C
10. Total power dissipation per output pair can be approximated by the following expression that includes device power dissipation plus power dissipation due to the
load circuit:
PD = [(22 + 0.61F) + [[(1550 + 2.7F)/Z) + (.0125FC)]N] x 1.1
See note 9 for variable definition.
11. In test mode, Max REF input frequency is 133MHz.
Document #: 38-07688 Rev. **
Page 8 of 12
CY7C9925
PRELIMINARY
Switching Characteristics Over the Operating Range [2, 12]
Parameter
Description
FS = LOW[1, 2]
FS = MID[1, 2]
FS = HIGH[1, 2 ]
FS=LOW
FS=MID
FS=HIGH
fNOM
Operating Clock
Frequency in MHz
FOUT
Output Frequency
FVCO
FBW
tU
tSKEWPR
tSKEW0
tSKEW1
tSKEW2
tSKEW3
tSKEW4
tDEV
tPD
tODCV3.3
tODCV2.5
tPWH3.3
tPWH2.5
tPWL3.3
tPWL2.5
tORISE
tOFALL
tLOCK
tJR
VCO Frequency
Loop Bandwidth
Programmable Skew Unit
Zero Output Matched-Pair Skew (XQ0, XQ1)[13, 15]
Zero Output Skew (All Outputs)[13, 16,17]
Output Skew (Rise-Rise, Fall-Fall, Same Class Outputs)[13, 18]
Output Skew (Rise-Fall, Nominal-Inverted, Divided-Divided)[13, 18]
Output Skew (Rise-Rise, Fall-Fall, Different Class Outputs)[13, 18]
Output Skew (Rise-Fall, Nominal-Divided, Divided-Inverted)[13, 18]
Device-to-Device Skew[14, 19]
Propagation Delay, REF Rise to FB Rise
Output Duty Cycle Variation at 3.3V[20]
Output Duty Cycle Variation at 2.5V[20]
Output HIGH Time Variation at 3.3V[21]
Output HIGH Time Variation at 2.5V[21]
Output LOW Time Variation at 3.3V[21]
Output LOW Time Variation at 2.5V[21]
Output Rise Time[21, 22]
Output Fall Time[21, 22]
PLL Lock Time[23]
Cycle-to-Cycle Output Jitter
RMS[14]
Peak-to-Peak[14]
Period Jitter
RMS[14]
Peak-to-Peak[14]
Phase Jitter
Peak-to-Peak[14]
tPJ
tPHJ
Min.
15
25
40
3.75
6.25
10
160
–
–
–
–
–
–
–
–
–0.15
47.5
45
47.5
45
47.5
45
0.15
0.15
–
–
–
–
–
–
Typ.
Max.
–
30
–
50
–
200
–
30
–
50
–
200
–
800
1
–
See Table 1
0.05
0.1
0.1
0.2
0.25
0.3
0.3
0.5
0.25
0.5
0.5
0.9
–
0.75
–
+0.15
50
52.5
50
55
50
52.5
50
55
50
52.5
50
55
1.0
1.5
1.0
1.5
–
0.5
–
15
–
100
–
25
–
150
–
100
Unit
MHz
MHz
MHz
MHz
ns
ns
ns
ns
ns
ns
ns
ns
%
%
%
%
%
%
ns
ns
ms
ps
ps
ps
ps
ps
Notes:
12. Test measurement levels for the CY7C9925 are TTL levels (1.5V to 1.5V). Test conditions assume signal transition times of 2 ns or less and output loading as shown
in the AC Test Loads and Waveforms unless otherwise specified.
13. SKEW is defined as the time between the earliest and the latest output transition among all outputs for which the same tU delay has been selected when all are
loaded with 30 pF and terminated with TTLAC Test Load.
14. Guaranteed by statistical correlation. Tested initially and after any design or process changes that may affect these parameters.
15. tSKEWPR is defined as the skew between a pair of outputs (XQ0 and XQ1) when all eight outputs are selected for 0tU.
16. tSKEW0 is defined as the skew between outputs when they are selected for 0tU. Other outputs are divided or inverted but not shifted.
17. CL=0 pF. For CL=30 pF, tSKEW0=0.35 ns.
18. There are three classes of outputs: Nominal (multiple of tU delay), Inverted (4Q0 and 4Q1 only with 4F0 = 4F1 = HIGH), and Divided (3Qx and 4Qx only in Divide-by-2
or Divide-by-4 mode).
19. tDEV is the output-to-output skew between any two devices operating under the same conditions (VCC ambient temperature, air flow, etc.)
20. tODCV is measure at VCCN/2.
21. Specified with outputs loaded with 30 pF for the CY7C9925 devices. Devices are terminated through 50Ω to VCC/2.tPWH is measured at 2.0V. tPWL is measured at
0.8V for 3.3V power supply. tPWH is measured at 1.7V. tPWL is measured at 0.7V for 2.5V power supply.
22. tORISE and tOFALL measured between 0.8V and 2.0V for 3.3V power supply. tORISE and tOFALL measured between 0.7V and 1.7V for 2.5V power supply
23. tLOCK is the time that is required before synchronization is achieved. This specification is valid only after VCC is stable and within normal operating limits. This parameter is
measured from the application of a new signal or frequency at REF or FB until tPD is within specified limits.
Document #: 38-07688 Rev. **
Page 9 of 12
CY7C9925
PRELIMINARY
AC Timing Diagrams
tREF
tRPWL
tRPWH
REF
tODCV
tPD
tODCV
FB
tJR
Q
tSKEWPR,
tSKEW0,1
tSKEWPR,
tSKEW0,1
OTHER Q
tSKEW2
tSKEW2
INVERTED Q
tSKEW3,4
tSKEW3,4
tSKEW3,4
REF DIVIDED BY 2
tSKEW1,3, 4
tSKEW2,4
REF DIVIDED BY 4
Ordering Information
Ordering Code
Package Type
Operating Range
CY7C9925LFXC
32-QFN package
Commercial, 0°C to 70°C
CY7C9925LFXT
32-QFN package - Tape and Reel
Commercial,0°C to 70°C
CY7C9925LFXI
32-QFN package
Industrial, –40°C to 85°C
CY7C9925LFXIT
32-QFN package - Tape and Reel
Industrial, –40°C to 85°C
Document #: 38-07688 Rev. **
Page 10 of 12
PRELIMINARY
CY7C9925
Package Drawing and Dimensions
32-Lead QFN (5 x 5 mm) LF32A
51-85188-**
All product and company names mentioned in this document are trademarks of their respective holders.
Document #: 38-07688 Rev. **
Page 11 of 12
© Cypress Semiconductor Corporation, 2004. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be
used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its
products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
CY7C9925
PRELIMINARY
Document History Page
Document Title: CY7C9925 3.3V/2.5V Programmable Skew Clock Buffer
Document Number: 38-07688
REV.
ECN NO.
Issue Date
Orig. of
Change
**
236309
See ECN
RGL
Document #: 38-07688 Rev. **
Description of Change
New Data Sheet
Page 12 of 12