Author Topic: LT3081 Lowest Maximum Limited Current Output?  (Read 1320 times)

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Offline KJ-90Topic starter

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LT3081 Lowest Maximum Limited Current Output?
« on: December 31, 2016, 03:10:39 pm »
I was wondering if anyone knows if the Linear Technologies LT3081 voltage regulator can be used with a limit resistor ( Ilim ), below 450 ohms to limit output currents to below 135mA. This would be in the voltage range from 2-8 Vdc for various LEDs, including the UV-C that operates on 6.5-8 Vdc at 60-80mA. The data sheet gives no minimum value for Ilim, and just says that a typical value is no less than 450 ohms. What would happen with lower values of current limiting resistors? The Rlim equation is also written in a confusing manner.
 

Offline StillTrying

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Re: LT3081 Lowest Maximum Limited Current Output?
« Reply #1 on: January 01, 2017, 07:38:06 pm »
used with a limit resistor ( Ilim ), below 450 ohms to limit output currents to below 135mA.

As I understand it, you don't need to go below 450 ohms because the programmed output current is already down to zero at 450 ohms.
The typical ratio of current limit to resistor value is 360mA/k? with a 450 ohm offset.

For 135mA I make it. 135mA = 135/360 kohm + 0.450 kohm  =  0.825 k

.  That took much longer than I thought it would.
 


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