Re: Low Zener Voltage?
- From: "Phil Allison" <philallison@xxxxxxxxxx>
- Date: Sun, 29 Jul 2007 12:55:28 +1000
"eromlignod"
This is a simple one. I've got a 0 to 5V square wave that I want to
convert to a 0 to 3.3V square wave. I tried putting a series resistor
and a 3.3V zener diode to ground.
The wave stays nice and square, but it comes out as 0 to 2.0 volts. I
have tried varying the value of the resistor, but it doesn't help.
What am I doing wrong?
** You did not READ the spec for your 3.3 volt zener.
Eg:
The 1N746A is a 400mW, *nominal* 3.3 volt zener, with rated test current of
20mA !!
The 1N4728 is a 1 watt, *nominal* 3.3 volt zener with rated tests current
of 76mA !!!!!
At low current of say 1 mA , the conduction voltage of either type may well
be only 2.0 volts.
Low voltage zeners are *darn soggy * and vague voltage references.
Change the zener to one with a higher * nominal* rated zener voltage, till
you get the 3.3 volts you want.
........ Phil
.
- References:
- Low Zener Voltage?
- From: eromlignod
- Low Zener Voltage?
- Prev by Date: Re: AA Battery capacity tester- resistor & clock
- Next by Date: Re: Low Zener Voltage?
- Previous by thread: Re: Low Zener Voltage?
- Next by thread: Re: Low Zener Voltage?
- Index(es):
Relevant Pages
|
|
