LM331: Reference design for 5 volts power supply
Part Number: LM331
I did LM331 board as expected, but I have a strange signal output which is coming worst with voltage increasing :
any idea ?
Please click on Insert/Edit Media button above and attach the schematic of your board showing all external component values, voltages and input signals.
Please note that Frequency Output, pin 3, is an open-collector output and thus requires a pullup resistor to work properly.
Marek Lis, MGTSSr Application EngineerPrecision Analog - TI Tucson
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In reply to Marek Lis:
please find here my schematic :
Any advise about this request ? could you look at my schematic please.
In reply to user4303883:
The LM331 frequency output, pin 3, is an open-collector output that requires a pullup resistor to work properly but your circuit has pin 3 floating - see below in blue box.
In order for the circuit to work properly, you must connect pin 3 thru 10k resistor to Vlogic - see in red box below.
I am sorry but I did not show you the right part of schematic, but I already have this pullup resistor, see below, so the problem is elsewhere.
Let's assume that you don't have a circuit connection problem on your LM331 PC board, then something else is preventing the circuit from functioning as expected. Here are some things I would check:
Do let us know if any of this helps get the circuit functioning.
Precision Amplifiers Applications Engineering
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