The E-series
is a system of preferred numbers
(also called preferred values) derived for use in electronic components. It consists of the E3, E6, E12, E24,
E48, E96 and E192 series, where the number after the 'E'
designates the quantity of value "steps" in each series. Although it
is theoretically possible to produce components of any value, in practice the
need for inventory simplification has led the industry to settle on the
E-series for resistors, capacitors, inductors, and Zener
diodes. Other types of electrical components are
either specified by the Renard series (for
example fuses) or are defined in relevant
product standards (for example IEC 60228 for
wires).
A decade of the
E12 values shown with their electronic color codes on resistors.
|
In the early 20th century,
resistor and capacitor value increments were much different than today. Over
time, products evolved towards common values. Based on some of these existing
conventions, the International Electrotechnical Commission (IEC) began
work on an international standard in 1948. The first version of this IEC
Publication 63 (IEC 63) was released in 1952. Later, IEC 63 was
revised, amended, and renamed into the current version known as IEC
60063:2015.
IEC
60063 release history:
·
IEC 63:1952 (aka IEC 60063:1952), first edition,
published 1952-01-01
·
IEC 63:1963 (aka IEC 60063:1963), second edition,
published 1963-01-01
·
IEC 63:1967/AMD1:1967 (aka IEC 60063:1967/AMD1:1967),
first amendment of second edition, published 1967
·
IEC 63:1977/AMD2:1977 (aka IEC
60063:1977/AMD2:1977), second amendment of second edition, published 1977
·
IEC 60063:2015, third edition, published
2015-03-27
|
E-series preferred
numbers were chosen such that when a component is manufactured that it will end
up in a range of roughly equally spaced values on a logarithmic scale. Each
E-series subdivides the interval from 1 to 10 (decade) into steps of 1, 3, 6,
12, 24, 48, 96, 192. Subdivisions of E3 to E192 ensure the maximum error will
be divided in the order of 40%, 20%, 10%, 5%, 2%, 1%, 0.5%. Also, the E192
series is used for 0.25% and 0.1% tolerance resistors.
Currently, the
E-series is split into two major groupings: up to E24 is one group, and E48 and
higher is the other group. The two main differences between each major group is
the number of significant digits (2 digits for E3 to E24, 3 digits for E48 to
E192) and different rounding rules. Since lower E-series up to E24 were defined
and established long before the IEC standards were written, older series were
not redefined when E48 to E192 series were created, otherwise it would have
created problems in production and servicing of established products. It should
be noted that some values in the E24 series don't exist in E48 to E192 series.
Example
The E3 series is defined as a
series of the numbers 1.0, 2.2 and 4.7. If a manufacturer sold resistors with
E3 series values in a range of 1 ohm to 10 megohms, then the available
resistance values would be: 1 Ω, 2.2 Ω, 4.7 Ω, 10 Ω,
22 Ω, 47 Ω, 100 Ω, 220 Ω, 470 Ω, 1 kΩ,
2.2 kΩ, 4.7 kΩ, 10 kΩ, 22 kΩ, 47 kΩ, 100 kΩ,
220 kΩ, 470 kΩ, 1 MΩ, 2.2 MΩ, 4.7 MΩ, 10 MΩ.
The E3 series is rarely used,
except for some components with high variations like electrolytic capacitors,
where the given tolerance is often unbalanced between negative and positive
such as −30/+50% or −20/+80%, or for components with uncritical values such as pull-up
resistors. The calculated tolerance for this series gives (3√10 − 1) ÷ (3√10 + 1) = 36.60%. While the
standard only specifies a tolerance greater than 20%, other sources indicate
40% or 50%. Currently, most electrolytic capacitors are manufactured with
values in the E6 or E12 series, thus E3 series is likely obsolete.
E24 vs. E48, E96, E192
Since
some values in the E24 series do not exist in the E48, E96 and E192 series,
resistor manufacturers have added the missing E24 values to some of their 1%,
0.5%, 0.25%, 0.1% tolerance families. This allows easier purchasing migration
between different tolerance parts. This type of combination is noted on
resistor datasheets and webpages as "E96 + E24" and "E192
+ E24"
Comparison of E24 vs. E48 values:
·
matching – 1.00, 1.10, 7.50
·
missing – 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.20, 2.40, 2.70,
3.00, 3.30, 3.60, 3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10
Comparison of E24 vs. E96 values:
·
matching – 1.00, 1.10, 1.30, 1.50, 2.00, 7.50
·
missing – 1.20, 1.60, 1.80, 2.20, 2.40, 2.70, 3.00, 3.30, 3.60,
3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10.
Comparison of E24 vs. E192 values:
·
matching – 1.00, 1.10, 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.40,
4.70, 7.50
·
missing – 2.20, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 5.10, 5.60,
6.20, 6.80, 8.20, 9.10
List of values for each E-series:
- E3 values (>20% tolerance)
- 1.0, 2.2, 4.7
- E6 values (20% tolerance)
- 1.0, 1.5, 2.2, 3.3, 4.7, 6.8
- E12 values (10% tolerance)
- 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
- E24 values (5% tolerance)
- 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1
- E48 values (2% tolerance)
- 1.00, 1.05, 1.10, 1.15, 1.21, 1.27, 1.33, 1.40, 1.47, 1.54, 1.62, 1.69, 1.78, 1.87, 1.96, 2.05, 2.15, 2.26, 2.37, 2.49, 2.61, 2.74, 2.87, 3.01, 3.16, 3.32, 3.48, 3.65, 3.83, 4.02, 4.22, 4.42, 4.64, 4.87, 5.11, 5.36, 5.62, 5.90, 6.19, 6.49, 6.81, 7.15, 7.50, 7.87, 8.25, 8.66, 9.09, 9.53
- E96 values (1% tolerance)
- 1.00, 1.02, 1.05, 1.07, 1.10, 1.13, 1.15, 1.18, 1.21, 1.24, 1.27, 1.30, 1.33, 1.37, 1.40, 1.43, 1.47, 1.50, 1.54, 1.58, 1.62, 1.65, 1.69, 1.74, 1.78, 1.82, 1.87, 1.91, 1.96, 2.00, 2.05, 2.10, 2.15, 2.21, 2.26, 2.32, 2.37, 2.43, 2.49, 2.55, 2.61, 2.67, 2.74, 2.80, 2.87, 2.94, 3.01, 3.09, 3.16, 3.24, 3.32, 3.40, 3.48, 3.57, 3.65, 3.74, 3.83, 3.92, 4.02, 4.12, 4.22, 4.32, 4.42, 4.53, 4.64, 4.75, 4.87, 4.99, 5.11, 5.23, 5.36, 5.49, 5.62, 5.76, 5.90, 6.04, 6.19, 6.34, 6.49, 6.65, 6.81, 6.98, 7.15, 7.32, 7.50, 7.68, 7.87, 8.06, 8.25, 8.45, 8.66, 8.87, 9.09, 9.31, 9.53, 9.76
- E192 values (0.5% and lower tolerance)
- 1.00, 1.01, 1.02, 1.04, 1.05, 1.06,
1.07, 1.09, 1.10, 1.11, 1.13, 1.14, 1.15, 1.17, 1.18, 1.20, 1.21, 1.23,
1.24, 1.26, 1.27, 1.29, 1.30, 1.32, 1.33, 1.35, 1.37, 1.38, 1.40, 1.42,
1.43, 1.45, 1.47, 1.49, 1.50, 1.52, 1.54, 1.56, 1.58, 1.60, 1.62, 1.64,
1.65, 1.67, 1.69, 1.72, 1.74, 1.76, 1.78, 1.80, 1.82, 1.84, 1.87, 1.89,
1.91, 1.93, 1.96, 1.98, 2.00, 2.03, 2.05, 2.08, 2.10, 2.13, 2.15, 2.18,
2.21, 2.23, 2.26, 2.29, 2.32, 2.34, 2.37, 2.40, 2.43, 2.46, 2.49, 2.52,
2.55, 2.58, 2.61, 2.64, 2.67, 2.71, 2.74, 2.77, 2.80, 2.84, 2.87, 2.91,
2.94, 2.98, 3.01, 3.05, 3.09, 3.12, 3.16, 3.20, 3.24, 3.28, 3.32, 3.36,
3.40, 3.44, 3.48, 3.52, 3.57, 3.61, 3.65, 3.70, 3.74, 3.79, 3.83, 3.88,
3.92, 3.97, 4.02, 4.07, 4.12, 4.17, 4.22, 4.27, 4.32, 4.37, 4.42, 4.48, 4.53,
4.59, 4.64, 4.70, 4.75, 4.81, 4.87, 4.93, 4.99, 5.05, 5.11, 5.17, 5.23,
5.30, 5.36, 5.42, 5.49, 5.56, 5.62, 5.69, 5.76, 5.83, 5.90, 5.97, 6.04,
6.12, 6.19, 6.26, 6.34, 6.42, 6.49, 6.57, 6.65, 6.73, 6.81, 6.90, 6.98,
7.06, 7.15, 7.23, 7.32, 7.41, 7.50, 7.59, 7.68, 7.77, 7.87, 7.96, 8.06,
8.16, 8.25, 8.35, 8.45, 8.56, 8.66, 8.76, 8.87, 8.98, 9.09, 9.20, 9.31,
9.42, 9.53, 9.65, 9.76, 9.88
|
|
|
No comments:
Post a Comment