Voltage regulator

G

goom

Senior Member
From a quick look at the data sheet, it appears that the input voltage should be at least 1.7V (Fig 4) and preferably 3V above the regulated voltage.
Not so sure about input current, but with efficiency quoted as 70%, I would suppose that Vin x Iin x 0.7 = Iout x Vout
 
B

BeanieBots

Moderator
ac21 said:
On a voltage regulator like lm2576t what is the min input current and/or voltage needed to achieve 3amps?
Click to expand...
It depends on your load but fig 4 of the datasheet in your link has all the answers.
Being a buck regulator, the input current will be lower than the output. A fair assumption would be 75% efficiency to base your calculations on.
 
A

ac21

Member
srnet said:
Dont you need to tell us which specific varient of the lm2576 you are using and the input and output voltages ?
Click to expand...
LM2576-5.0 (non HV)


Basically I mean 12v 1 amp going in, out would be 5v and how many amps?

Would this change if it was 24v 1 amp in?
 
S

srnet

Senior Member
A reasonable rule is to assume 80% efficiency, although it could be a bit more.

So input power = 12Volts x 1Amp = 12Watts

Output power = 12Watts x 80% = 9.6Watts

Available output current = 9.6Watts / 5Volts = 1.92Amps
 
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