In current transformer applications it is necessary to place a burden 
resistor across the output of the transformer.  From a design standpoint the 
primary function is to limit the output voltage so that the transformer is 
not allowed to saturate.  From a circuit design point of view thje burden 
resistor is used to adjust the output of the transformer to the desired 
output for the particular circuit.  In reality both of  these criteria must 
be dealt with.

	Instead of designing current traansformers to operate with a given 
burden resistor value we suggest the following approach:
	1.	Select a current transformer that has the mechanical 
		specifications that you need and that is rated to handle your 
		maximum current.
	2.	Determine the maximum output voltage for the selected part at 
		the frequency you are going to operate at (see example).  Use 
		the smaller of this value or the maximum output voltage you 
		need for your application.  Let this value be Vmax.  If your 
		circuit requires a higher output voltage amplify the output.  
		(Refer to our application note #108).
	3.	Determine the maximum current that you would like to measure 
		and divide this value by the number of turns in the secondary 
		winding of the current transformer.  This is the maximum current 
		that will flow in the secondary.  This value is Isecondary.
	4.	The correct burden resistor is found by dividing Vmax by 
		Isecondary.
Example:  Using an HL-IH250f/ current transformer to measure current to 100 
		amps at 60 hz.  From the catalog data listing for the HL-IH250F/ 
		the maximum output voltage is 0.40 Volts.  100 Amps divided by 
		500 turns gives us a value of secondary current of 0.20 Amps.  
		0.40 Volts divided by 0.20 Amps gives us a value for the burden 
		resistor of 2.0 Ohms.

	If you want to operate at 400 Hz the maximum output voltage can be 
	calculated using: