Wednesday, 11 September 2013

Standard Resistor Values & Color Coding



Standard Resistor values:
  
IEC60063 defines the preferable numbers for passive components. There are E6, E12, E24, E48, E96, E192 series resistors. E6 series resistors have 20% tolerance. E12 series resistors have 10% tolerance. E24 series resistors have 5% tolerance. E48 resistors have 2% tolerance. E96 resistors have 1% tolerance. E192 resistors have 0.5% tolerance. 1% tolerance resistors are available in E24 series also. 0.1%, 0.25% resistors are also available in E192 series

E6 Series (20%):

E12 Series (10%):


E24 Series (5%):
E48 Series (2%):
E96 Series (1%):
E192 Series (0.5%, 0.2%, 0.1%):
Standard resistance value can be obtained by multiplying any value shown in above tables by 10^x (i.e. 10 to the power x). ‘x’ can be any integer.

Color Coding:


 

In 4 band resistor code, first 2 lines represent significant, third line represents multiplier, 4th line represents tolerance. In 5 band resistor code 4th line is the multiplier and 5th line represents tolerance. In 6 band resistor 4th line is the multiplier and 5th line is tolerance, 6th line is temperature coefficient.

For example consider a 5 band resistor with first line Brown, 2&3rd line Black, 4th line represents Red, 5th line is Brown. Then resistance value is calculated as




Value is 100x100=10000=10Kohm
Since 5th line is Brown, tolerance is 1%. So the resistor is a 10K, 1% resistor.  
SMD Resistor marking:
                SMD chip resistors have 3-digit or 4-digit code marked on them. Recently new coding system (EIA-96) is being used for marking.
3-digit code:
          In the 3-digit code, first two numbers represent significant digits. Third digit is multiplier. Third digit represents power of 10. For example consider above marking, here multiplier (3rd digit) 4 means “10 to the power 4” is the multiplier. So resistance value is 10 X  = 100K Ohm 
        ‘R’ is used to indicate decimal point in resistance value. For example ‘10R’ is the marking on the resistor then, it is 10ohm resistor. ‘4R7’ is the marking then resistance value is 4.7Ohm.
4-digit code:  

In the 4-digit code, first three numbers represent significant digits. Fourth digit is multiplier. Fourth digit represents power of 10. For example consider above marking, here multiplier (4th digit) 2 means “10 to the power 2” is the multiplier. So resistance value is 150 X  = 15K Ohm
‘R’ is used to indicate decimal point in resistance value. For example ‘10R0’ is the marking on the resistor then, it is 10ohm resistor. ‘470R’ is the marking then resistance value is 470 Ohm.
EIA-96 code:

In this code, first two numbers represent significant information about resistance value. Refer to the below table for the equivalent resistance value against two digit number. Third alphanumeric is multiplier.
Multiplier: 

For example marking on the resistor is ‘10C’, and then resistance value is 124 X 100 =12.4K ohm (10 means from table 124).
Resistor packages:
The following are the surface mount packages and their corresponding wattage and dimensions.
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