how to make a low voltage clamp or limiter

[Fibo]

Does anyone know how I could protect a load from exceeding two
different voltages...

I have a load that I want to keep within +1.6V and -0.6V.... I can't
exceed these values, and have to be within 200mV of them

I thought about putting a 1.6V zener across my load, that way in one
direction it wouldn't go over 1.6V and in the other direction it would
be limited to about 0.6V... but I can't find any 1.6V zeners...

Does anyone know another way I could pull this off?

- much thanks

 

[Eeyore]

Does anyone know how I could protect a load from exceeding two
different voltages...

I have a load that I want to keep within +1.6V and -0.6V.... I can't
exceed these values, and have to be within 200mV of them

I thought about putting a 1.6V zener across my load, that way in one
direction it wouldn't go over 1.6V and in the other direction it would
be limited to about 0.6V... but I can't find any 1.6V zeners...

Does anyone know another way I could pull this off?

How accurate do those voltages have to be ?

Graham

 

[Jean-Christophe]

Does anyone know how I could protect a load from exceeding two
different voltages...

I have a load that I want to keep within +1.6V and -0.6V.... I can't
exceed these values, and have to be within 200mV of them

I thought about putting a 1.6V zener across my load, that way in one
direction it wouldn't go over 1.6V and in the other direction it would
be limited to about 0.6V... but I can't find any 1.6V zeners...

Does anyone know another way I could pull this off?

Self-made 1.6V zener : two or three diodes in series.
Then a diode in reverse parallel and you have your limiter.

 

[Fibo]

Self-made 1.6V zener : two or three diodes in series.
Then a diode in reverse parallel and you have your limiter.

ahhh.... I like this 2 or 3 diode solution... sounds promising, thanks

my accuracy has to be within +/- 200mV

and my load will be pulling around 100uA

 

[Jean-Christophe]

ahhh.... I like this 2 or 3 diode solution... sounds promising, thanks
my accuracy has to be within +/- 200mV
and my load will be pulling around 100uA

Now, if the supply voltage goes over 1.6V ( or below -0.6V )
the current thru the diodes could destroy them,
so you sould limit the supply current somehow.

 

[whit3rd]

Does anyone know how I could protect a load from exceeding two
different voltages...

I have a load that I want to keep within +1.6V and -0.6V.... I can't
exceed these values, and have to be within 200mV of them

Meaning, that the signal has to accurately track an input up to
200 mV of those limits? Or, that the limits can vary from
+1.6 +0.200V to +1.6 - 0.200V?

How accurate? What input drive is available, and what output current
is required? Is this an analog signal with accuracy requirements, or
just a logic level ON/OFF?

One way is to buffer with an op amp with rail/rail output, and
voltage-divide the output down to the range you want. The slew rate
will suffer, and you need to have a reference voltage to bias the
center off ground. There are also amplifiers (LM13700) which can
be accurately current-limited, and a load resistor to the midpoint of
your selected range will accomplish the same thing, with better
recovery times after clipping, and better slew rates.

There aren't any good Zeners in the low range you want, of course.
The best environment for diode/Zener clippers is the old analog
+/- 24V power regime. With lotsa volts to start with, circuitry gets
less complex.

 

[default]

ahhh.... I like this 2 or 3 diode solution... sounds promising, thanks

my accuracy has to be within +/- 200mV

and my load will be pulling around 100uA

A " 'load' of 100 qua?" two silicon signal diodes and one germanium
should be 1.5 volts.

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