Hi. I have three different LM338T voltage regulators from one +9V input source. One IC would regulate at +6V, one at +5V and one at +3V. My problem: the +6V regulator is used to drive a 2A load. When driving this load, the +5V would drop down to about 4.5V or more, while the +3V seemed unaffected. The voltage regulation in the LM338T should have prevented this from happening. Is this true? If not please refer to the attached circuit and advise on modification(s) to prevent this problem. Thank you.

 

Does your 9V input stay at 9 volts with a 2 amp load?

 

Hi BReeves. I did not monitor the source. I should have. It just skipped my mind. I will verify. I am using a 2A bench power supply. Your question now prompted me to think of my inapt power supply. I will first verify the source to confirm my suspicion. Or just to be safe I might as well use a higher rated power supply. Thank you.