Electronics > Beginners
Is there any advantage of Zener Diode as regulator over LDO other than BOM cost?
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RoadRunner:
i am currently looking through frequency counter stuff, there is one little prescaler circuit which divides couples of Ghz down to Tens of Mhz. and in this section circuit has  simple Zener Diode with and resistor to power presclaer chip with around 5V and current less than 10mA.

i am thinking why did the person who designed it, didn't used a simple LDO. was BOM cost only concern?

is there any advantage of Zener diode and resistor based regulator vs LDO , other than cost ?

any help will be highly appreciated.
Cliff Matthews:
Where you checking without an active input? Try measuring >1 Ghz..
bd139:
Zener blows off more power to regulate the same load. Plus the regulation is worse even if you get the zener on the lowest part of the dV curve which usually requires a lot of current. Also if zener goes pop, the circuit will fail to the input voltage likely destroying everything after it.
RoadRunner:

--- Quote from: Cliff Matthews on June 01, 2018, 11:10:06 am ---Where you checking without an active input? Try measuring >1 Ghz..

--- End quote ---

i am not doing any measurement right now. i have only schematic not the board itself.  Measurement is not my primary concern i just wondered about question why a zener not a LDO.
David Hess:
Why make things complicated when they can be simple?

With a zener diode, there is none of that nonsense about frequency compensation.  Noise is good.  Line and load regulation is not as good at low frequencies but can be better at high frequencies.
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