參數(shù)資料
型號(hào)： A129A
英文描述： IC
中文描述： 集成電路
文件頁(yè)數(shù)： 2/31頁(yè)
文件大小： 226K
代理商： A129A
SPECIFYING QUARTZ CRYSTALS
A typical quartz crystal specification reads like this:
35.0MHz HC49 15 30 20 SR 3RD BU T
Frequency
Holder Style
Frequency Tolerance at 25°C
Frequency Stability
Lower end of Operating Temp Range
Circuit Condition
Overtone order
Packaging
Additional Text Code (for non-standard product)
Thefollowingnotesdefineeachelementofthespecification.
Frequency
Frequency is normally specified in kilohertz (kHz) up to
999.999kHz and in megahertz (MHz) from 1.0MHz. All
our computer-generated transaction documents follow this
standard convention automatically.
Thefrequencyshouldbegiventosevensignificantfigures.If
seven significant figures are not used, any figure that might
follow those given will be taken as zero. Thus a frequency
given as 16.6MHz will be taken as 16.60, not 16.66667.
Some specifiers extend the use of kHz to all crystals
operating in fundamental mode, reserving MHz for
overtones. To minimise the possibility of misunderstanding
it is best to use the standard method and specify the mode.
Holder Style
Before manufacture of the crystal can start, the holder style
must be defined. If the holder size is not known or it is
unimportant,wewillsupplytheholdernormallyadoptedfor
the frequency specified, such as HC49 for the majority of
microprocessorapplications.Theholderinformationshould
alsocoveranymechanicalvariantrequiredsuchasatopwire
or cropped leads. The following variants for example are
available for most crystals, either singly or in some cases, in
combination:
3 lead base
Top wire
Insulating sleeve
Taped and reeled
Fitted insulator
Cropped leads
Formed leads
Frequency Tolerance
The cost of manufacture depends partly on the accuracy
required at the reference temperature (which in the case of
the AT-cut crystal, is usually 25°C).
Where high initial accuracy is important the additional
manufacturing cost should be weighed against the cost of
includingafrequencytrimmingfacilitywithintheoscillator.
Frequency Stability
Frequency stability is normally specified as a frequency
tolerance over a defined operating temperature range with
respect to the frequency at reference temperature. The
temperature ranges are defined for each crystal in the
relevant data sheet. However the majority of crystals will
continue to operate quite satisfactorily outside the
temperature range for which they are specified, but with a
possible degradation of their frequency stability.
Generalised frequency vs temperature curves for the AT-cut
crystal types are illustrated in the following pages. These
indicate that, without compensation, a crystal specified for
operation over a wide frequency range will probably have an
inferior performance over a narrower range than one whose
design was optimised for the narrower range. The angle of
cut of the quartz blank from its quartz stone determines
which curve will be followed; the chosen angle being subject
to its own tolerance. Thus, since manufacturing cost is
tolerance-dependent it is wise not to specify a wider
operating temperature range than is actually needed unless
some sacrifice of stability, or an increase in cost, can be
accepted.
Standard Frequency Tolerances and Stabilities
±5ppm, ±10ppm, ±15ppm, ±20ppm, ±30ppm,
±50ppm, ±100ppm
Operating Temperature Ranges
0 to 50°C
–10 to 60°C
–20 to 70°C
–30 to 80°C
–40 to 90°C
–55 to 105°C
–55 to 125°C
When the required temperature range is symmetrical about
25°C, it is indicated in the specification by the lower figure,
ie: –20 to 70°C would read ‘20’ as shown in the example. If
the required temperature range is not symmetrical about
25°C, both figures are used, ie: –55 to 85°C and appear in
the additional text code section (T).
Circuit condition
The characters ‘SR’ are used to denote calibration of the
crystal at series resonance. If it is to be calibrated at load
resonance the characters represent the circuit load
capacitance in pF.
Packaging Codes
Tape & Reel packaging is available as an option on many of
the products outlined in the Quartz Crystal chapter.
EuropeTel:+44(0)146074433
Fax:+44(0)146072578
2
Americas Tel:+19199410430
Fax:+19199410530
Q
C
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A12AB 功能描述:SWITCH TOGGLE SPDT .4VA PC MNT RoHS:是 類(lèi)別:開(kāi)關(guān) >> 撥動(dòng)開(kāi)關(guān) 系列:A 標(biāo)準(zhǔn)包裝:1 系列:A 電路:雙刀雙擲 開(kāi)關(guān)功能:開(kāi)-開(kāi)-開(kāi) 觸點(diǎn)額定電壓:6A @ 125VAC 觸動(dòng)器類(lèi)型:扁平型 觸動(dòng)器長(zhǎng)度:11.38mm 發(fā)光:不發(fā)光 安裝類(lèi)型:面板安裝 端接類(lèi)型:焊片 軸襯螺紋:1/4-40 包裝:散裝
A-12AB 制造商:Nihon Kaiheiki Ind Co Ltd 功能描述:28V 100000 Gold 85 -30 10.46mm 5.84mm 23.1mm
A12AB1 功能描述:SW TOGGLE SPDT STR IN BRKT PCB RoHS:是 類(lèi)別:開(kāi)關(guān) >> 撥動(dòng)開(kāi)關(guān) 系列:A 標(biāo)準(zhǔn)包裝:1 系列:A 電路:雙刀雙擲 開(kāi)關(guān)功能:開(kāi)-開(kāi)-開(kāi) 觸點(diǎn)額定電壓:6A @ 125VAC 觸動(dòng)器類(lèi)型:扁平型 觸動(dòng)器長(zhǎng)度:11.38mm 發(fā)光:不發(fā)光 安裝類(lèi)型:面板安裝 端接類(lèi)型:焊片 軸襯螺紋:1/4-40 包裝:散裝
A12AB1-GA 制造商:NKK Switches 功能描述:SUBMINIATURE TOGGLE/PC 制造商:NKK Switches 功能描述:SWITCH TOGGLE SPDT 0.4VA 28V
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