CY23FS08 Cypress Semiconductor, CY23FS08 Datasheet - Page 9

• Manufacturer Part Number: CY23FS08
• Description: Failsafe 2.5 V/3.3 V Zero Delay Buffer
• Manufacturer: Cypress Semiconductor

www.DataSheet4U.com
Table 4. Pullability Range from XTAL with Different C0/C1
Ratio
Calculated value of the pullability range for the XTAL with C0/C1
ratio of 200, 300, and 400 are shown in
calculation C
Using a XTAL that has a nominal frequency specified at load
capacitance of 14 pF, almost symmetrical pullability range is
obtained.
Next, it is important to calculate the pullability range including
error tolerances. This is the capture range of the input reference
frequency that the FailSafe device and XTAL combination can
reliably span.
Document Number: 38-07518 Rev. *F
C0/C1 Ratio
200
300
400
LOADMIN
-100
-200
-300
-400
400
300
200
100
0
C
6
LOADMIN
= 8 pF and C
8
8
8
8
10 12 14 16 18 20 22 24 26 28 30 32 34
Figure 13. Frequency vs. C
C
LOADMAX
LOADMAX
32
32
32
Pullability Range vs. C
(Normalized to 14pF C
Table
= 32 pF is used.
–385
–256
–192
Pullability
C
4. For this
Range
LOAD
(pF)
333
222
166
LOAD
Calculating the capture range involves subtracting error
tolerances as follows:
Parameter ........................................................ f error (ppm)
Manufacturing frequency tolerance ...................................15
Temperature stability ..........................................................30
Aging ................................................................................... 3
Board/trace variation ........................................................... 5
Total ...................................................................................53
Example: Capture Range for XTAL with C0/C1 Ratio of 200
Negative Capture Range= –385 ppm + 53 ppm = –332 ppm
Positive Capture Range = 333 ppm – 53 ppm = +280 ppm
It is important to note that the XTAL with lower C0/C1 ratio has
wider pullability/capture range as compared to the higher
C0/C1 ratio. This helps to select the appropriate XTAL for use in
the FailSafe application.
Behavior for Example XTAL
LOAD
LOAD
)
C0/C1 = 200
C0/C1 = 300
C0/C1 = 400
CY23FS08
Page 9 of 15
[+] Feedback