Hello.
Since there are a lot of topics about Jung`s regulator I`ll try to seek answers here.
I have some problems with running 5V regulator properly.
Configuration for now is like that:
Vin 9V,
LM4040 2.5v as vref
R6-R7 are equal : 1k.
Ir for LM4040 is 1.2k
Opamp is 5534 as a testing gear, and AD797 with power supplied from unregulated source, and AD797 power supplied from regulator circuit.
Zener is 2.5V
Everything else is like in Diddens article.
Results of Vout are:
5534 - 5.30V
797 from unregulated power source - 5.30V
797 powered from circuit - 2.298V
What could go wrong here?
Since there are a lot of topics about Jung`s regulator I`ll try to seek answers here.
I have some problems with running 5V regulator properly.
Configuration for now is like that:
Vin 9V,
LM4040 2.5v as vref
R6-R7 are equal : 1k.
Ir for LM4040 is 1.2k
Opamp is 5534 as a testing gear, and AD797 with power supplied from unregulated source, and AD797 power supplied from regulator circuit.
Zener is 2.5V
Everything else is like in Diddens article.
Results of Vout are:
5534 - 5.30V
797 from unregulated power source - 5.30V
797 powered from circuit - 2.298V
What could go wrong here?
Which type of regulator?
AD797 is faster than 5534, so fluttering may occur.
BTW 1k2 (2mA) is IMHO too much for LM4040, 0.2 .. 0.5mA is enough.
Only part 3 is written by Jan so I assume it is Figure 2 of that part you have been trying to follow.
"What could go wrong here?"
NE5534 has a typical quiescent current of 4mA with a max. of 8mA, load current disregarded. NE5543 can operate from 6V but the output swing will be very limited.
AD797 has a typical quiescent current of 8mA with a max. of 10mA, load current disregarded. AD797 can operate from 10V but the output swing will be limited.
"R6-R7 are equal : 1k." I cannot find R7 on the diagram but let us look at R6. R6 was 22 Ohm but you have increased it to 1K - quite an increase! The supply current to the OP-AMP is running through R6.
4mA (NE5534) through 1K means a voltage drop of 4V but it may be more if not typical and with load current. Your input voltage is 9V and with a best case drop of 4V, you best case have a supply voltage for an NE5534 of 5V. That is below the operating voltage range of the OP-AMP even best case! You cannot expect the NE5534 to work the way you hope.
8mA (AD797) through 1K means a voltage drop of 8V but it may be more if not typical and with load current. Your input voltage is 9V and with a best case drop of 8V, you best case have a supply voltage for an AD797 of 1V! It is impossible that an AD797 may work in any way even best case!
"Ir for LM4040 is 1.2k". What is Ir? Is it R1?
For the time being the voltage regulator is not in regulation.
Solution: Change R6 into 10-22 Ohm, no more. Forget about use of an AD797 - it requires more voltage to operate than you have even at the input. The NE5534 may function.
"What could go wrong here?"
NE5534 has a typical quiescent current of 4mA with a max. of 8mA, load current disregarded. NE5543 can operate from 6V but the output swing will be very limited.
AD797 has a typical quiescent current of 8mA with a max. of 10mA, load current disregarded. AD797 can operate from 10V but the output swing will be limited.
"R6-R7 are equal : 1k." I cannot find R7 on the diagram but let us look at R6. R6 was 22 Ohm but you have increased it to 1K - quite an increase! The supply current to the OP-AMP is running through R6.
4mA (NE5534) through 1K means a voltage drop of 4V but it may be more if not typical and with load current. Your input voltage is 9V and with a best case drop of 4V, you best case have a supply voltage for an NE5534 of 5V. That is below the operating voltage range of the OP-AMP even best case! You cannot expect the NE5534 to work the way you hope.
8mA (AD797) through 1K means a voltage drop of 8V but it may be more if not typical and with load current. Your input voltage is 9V and with a best case drop of 8V, you best case have a supply voltage for an AD797 of 1V! It is impossible that an AD797 may work in any way even best case!
"Ir for LM4040 is 1.2k". What is Ir? Is it R1?
For the time being the voltage regulator is not in regulation.
Solution: Change R6 into 10-22 Ohm, no more. Forget about use of an AD797 - it requires more voltage to operate than you have even at the input. The NE5534 may function.
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It's not your resistors. Please read what is posted. You try to use an opamp at 5V supply which is not specified for that. You need to get an opamp specified for 5V supply.
From the last doc you quoted (did you read it?):
Last important point: as the opamp is supplied from the output voltage, you must use an
opamp that will work on this voltage. For high output voltages check the maximum opamp total
supply voltage; at the other side, for 5V or 3,3V make sure the opamp works with supplies
down to those values. This may be a good opportunity to actually read a data sheet ;-).
Jan
From the last doc you quoted (did you read it?):
Last important point: as the opamp is supplied from the output voltage, you must use an
opamp that will work on this voltage. For high output voltages check the maximum opamp total
supply voltage; at the other side, for 5V or 3,3V make sure the opamp works with supplies
down to those values. This may be a good opportunity to actually read a data sheet ;-).
Jan
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I was referring to the articles you directed me to for a start. 3rd article written by Jan, Figure 2. R6 is in series with the OP-AMP supply.
The articles seem now to have been removed and I understand that you actually used a different circuit diagram.
"What could go wrong here?" - poor coordination.
Jan must be the ultimate guide to solve your issues.
With the zener 2V5 (in place of the 6V8) that is 5V95 at the base pass transistor and (minus 0V6) 5V35 output.
your reference voltage
and that supposes an output of 2x2V53=5V06 and a zener 5V06-3V45=1V61 !
If that IS the zener voltage all is ~right.Only the 20mV difference +in versus -in is too much but perhaps a little measuring error.
Mona
Jan,
funny thing is that if I connect opamp power input to regulator`s power rail, results are the same. 5,3V on the output and non inverting input = 2,51V inverting input = 2,53V.
What is even more interesting, 3.3V regulator with ad797 seems to work properly.
I`ll try with ad817 or lme49710.
funny thing is that if I connect opamp power input to regulator`s power rail, results are the same. 5,3V on the output and non inverting input = 2,51V inverting input = 2,53V.
What is even more interesting, 3.3V regulator with ad797 seems to work properly.
I`ll try with ad817 or lme49710.
You tryed what, replaced the zener at the opamp output by two diodes as Jan proposed or evt by a led ?
If a divider (1k+1k) from 5V3 doesn't produce 2V65 but 2V53 there is something wrong.A resistor not 1k or a leaking diode ... Not the capacitor leaking, gives a deviation the other way.
Mona
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