Specifying TCXOs
A typical TCXO specification reads like this:
The following notes define each element of the specification.
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.
The frequency should be specified to seven significant figures. If seven significant figures are not used, we assume that any figure that might follow those given may be taken as zero. Thus a frequency given as 16.6MHz will be taken as 16.60, not 16.6666.
Please contact the sales office for details of developed frequencies.
Model Number
The model number incorporates information which describes output compatibility and holder style.
Frequency Stability
The frequency stability is the frequency change over the operating temperature range.
In tight tolerance applications it may be necessary to apply a frequency offset at 25°C in order to centralise the frequency/temperature characteristic to the nominal frequency. If applicable this will be stated in the individual data sheet.
The following codes apply for the frequency stability:
A = ±0.3ppm H = ±2.5ppm
B = ±0.8ppm J = ±3.0ppm
C = ±1.5ppm K = ±5.0ppm
D = ±0.25ppm L = ±10.0ppm
E = ±0.5ppm M = ±0.2ppm
F = ±1.0ppm N = ±15.0ppm
G = ±2.0ppm T = ±0.9ppm
Frequency Trimming
In order to meet their specification over their full operating temperature range, close tolerance devices are often adjusted to have a frequency offset at room temperature, therefore adjustment of the mechanical trimmers of such devices should not be attempted, therefore, unless facilities exist to measure their frequency over their full operating temperature range.
Operating Temperature Range
Although in general these devices will continue to operate outside their normal temperature range with a degradation in frequency stability, damage can result if the temperatures reached are excessive.
The following codes apply for Operating Temperature Ranges:
C = 0 to 70°C U = –30 to 75°C
G = –20 to 75°C V = –30 to 80°C
H = –55 to 95°C W = –30 to 85°C
P = 0 to 50°C X = –40 to 85°C
R = –10 to 60°C Y = –55 to 105°C
S = –20 to 70°C Z = –55 to 125°C
T = –25 to 75°C
Packaging Code
Tape and Reel packaging is available as an option on many of the products outlined in this chapter.
Unless individual data sheets state tape and reel packaging, items will be bulk packed. Please note: only complete reels are sold.
BU = Bulk packed
TR = Tape & Reel packed
Additional Text Code
If the product is non-standard, the letter ‘T’ will appear at the end of the product specification. This refers to additional text on the quotation/sales order to identify the non-standard requirements.
Outline Drawings
Dimensions on the drawings are shown only as a guide. Precise dimensions of the holders are available upon request. All dimensions are shown in mm and are nominal unless otherwise stated.
Offset Frequency
The frequency difference, positive or negative, (expressed in Hz) which should be added to the nominal frequency when setting the oscillator at the specified temperature (usually 25°C). The purpose is to minimise the frequency deviation over the entire operating temperature range. Each oscillator will have its own offset frequency marked on the case.
In the example shown in Fig 1. (overleaf), the dotted line shows that if the oscillator is set to nominal frequency at 25°C, the frequency deviates from –1.7ppm to +0.3ppm over the temperature range. By setting the frequency at 25°C to the specified offset frequency, the overall frequency deviation is reduced to ±1.0ppm.
Marking
Product will be marked as detailed in the individual data sheets. Where space is limited some or all of the information will be omitted/truncated at IQD’s discretion. Full product description will be found on the individual batch packaging.
Ordering Information
See individual data sheets