bsiegel

July StudentZone Quiz Solution

Discussion created by bsiegel Employee on Jul 17, 2017

You are still using the standard 7805 to get a stable 5V output?

Well you need 7V (minimum)  Input Voltage for the 7805

Let say we need 100mA Output Current.

 

Which efficiency you will get from the 7805 versus an LDO like the ADP150?

Tip: Datasheet of the ADP150: http://www.analog.com/en/products/power-management/linear-regulators/adp150.html

 

 

Solution:

7805

Ptot= (Vin-Vout) *Iout = (7V-5V)*0,1A = 0,2W

Ptot equals to heat you need to distribute.

Pab=5V*0,1A = 500mW

n=Pab/Pzu=500mw/700mW  ~71%

 

ADP150

Vin(min)= Vout+0,4V

Vout=5V

Vin= 5,4V

Ptot =0,4V*0,1A = 0,04W

Pab=500mW

 

n=Pab/Pzu = 500mW/540mW ~ 92%

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