32.768–kHz Oscillator Specifications

Parasitic capacitance off-chip

 

 

 

 

 

 

between TXTAL or TEXTAL and VSS

2

pF

 

 

 

 

 

 

 

 

Parasitic resistance between

10

 

M

Ω

TXTAL or TEXTAL to VSS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Parasitic resistance between

10

 

M

Ω

TXTAL and TEXTAL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C.1.2 Quartz Crystal Specification

The following specifications for the quartz crystal are shown in the figure and table below.

Resonance frequency (fs): Motional capacitance (Cm): Motional inductance (Lm):

Resonance frequency of the crystal.

Equivalent serial capacitance in the crystal model.

Not generally given in supplier specification.

Equivalent serial resistance in the crystal model. Some crystal providers refer to this resistance as the Equivalent Series Resistance (ESR) or simply Series Resistance.

Motional resistance (Rm):

Other providers supply a Quality Factor, Q, instead of Rm;

 

therefore, the values for Q

 

corresponding to specified range of Rm are supplied in the

 

following table.

Shunt capacitance (Co):

Parasitic capacitance between Q1 and Q2.

Load capacitance (CL):

Needed load capacitance viewed by the crystal to oscillate at fs.

Drive level:

Power dissipated in the equivalent serial resistance (Rm).

Aging:

Resonance frequency shift due to aging.

 

 

Co

Q1

 

 

Cm

Lm

Rm

Q2

Specification

Minimum

Typical

Maximum

Unit

 

 

 

 

 

Resonance frequency (fs)

32768

Hz

 

 

 

 

 

Quality factor (Q)

40K

80K

200K

 

 

 

 

 

Motional capacitance (Cm)

2

3

4

fF

 

 

 

 

 

Motional resistance (Rm)

50K

W

 

 

 

 

 

Shunt capacitance (Co)

0.9

2

pF

 

 

 

 

 

SA-1100 Developer’s Manual

C-3

Page 383
Image 383
Intel SA-1100 Other providers supply a Quality Factor, Q, instead of Rm, Therefore, the values for Q, Following table