C9630 Datasheet, PDF (16/18 Pages) Cypress Semiconductor – PC133 Clock Generator for SiS630/Pentium III & SiS540/Socket7 Applications

APPROVED PRODUCT
C9630
PC133 Clock Generator for SiS630/Pentium^®III & SiS540/Socket7 Applications
Suggested Oscillator Crystal Parameters
Characteristic
Symbol Min
Typ
Max
Units Conditions
Frequency
Tolerance
Operating Mode
F_o
12.00 14.31818
16.00
MHz
T_C
-
-
+/-100
PPM Note 1
T_S
-
-
+/- 100
PPM Stability (T_A -10 to +60C) Note 1
T_A
-
-
5
PPM Aging (first year @ 25C) Note 1
-
-
-
-
Parallel Resonant, Note 1
Load Capacitance
C_XTAL
-
16
-
pF The crystal’s rated load. Note 1
Effective Series
R_ESR
-
40
Resistance (ESR)
-
Ohms Note 2
Note1: For best performance and accurate frequencies from this device, It is recommended but not mandatory that the
chosen crystal meets or exceeds these specifications
Note 2: Larger values may cause this device to exibit oscillator startup problems
To obtain the maximum accuracy, the total circuit loading capacitance should be equal to C_XTAL. This loading
capacitance is the effective capacitance across the crystal pins and includes the clock generating device pin
capacitance (C_FTG), any circuit traces (C_PCB), and any onboard discrete load capacitors (C_DISC).
The following formula and schematic may be used to understand and calculate either the loading specification of a crystal for a
design or the additional discrete load capacitance that must be used to provide the correct load to a known load rated crystal.
CL = (CXINPCB + CXINFTG + CXINDISC) X (CXOUTPCB + CXOUTFTG + CXOUTDISC)
(CXINPCB + CXINFTG + CXINDISC) + (CXOUTPCB + CXOUTFTG + COUTDISC)
Where:
C_XTAL = the load rating of the crystal
C_XOUTFTG = the clock generators XIN pin effective device internal capacitance to ground
C_XOUTFTG = the clock generators XOUT pin effective device internal capacitance to ground
C_XINPCB = the effective capacitance to ground of the crystal to device PCB trace
C_XOUTPCB = the effective capacitance to ground of the crystal to device PCB trace
C_XINDISC = any discrete capacitance that is placed between the XIN pin and ground
C_XOUTDISC = any discrete capacitance that is placed between the XOUT pin and ground
C_XINPCB
C_XOUTPCB
C_XINDISC
XIN
C_XINFTG
C_XOUTDISC
XOUT ^CXOUTFTG
Clock Generator
As an example, and using this formula for this datasheet’s device, a design that has no discrete loading capacitors
(C_DISC) and each of the crystal to device PCB traces has a capacitance (C_PCB) to ground of 2pF (typical value) would
calculate as:
CL = (2pF + 30pF + 0pF) X (2pF + 30pF + 0pF) = 32 X 32 = 16 pF
(2pF + 30pF + 0pF) + (2pF + 30pF + 0pF) 32 + 32
Therefore to obtain output frequencies that are as close to this data sheets specified values as possible, in this design
example, you should specify a parallel cut crystal, with C_L = 16pF.
Cypress Semiconductor Corporation
525 Los Coches St.
Milpitas, CA 95035. Tel: [phone], Fax: [phone]
http://www.cypress.com
Document#: 38-07035 Rev. **
05/02/2001
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