LM358-N: LM358 vs LM358N

Chao Chang

Prodigy 140 points

Part Number: LM358-N
Other Parts Discussed in Thread: LM393, LM358,

I have done circuit experiments on LM385(SOIC-8) and LM385N(PDIP). The schematic diagrams are shown as,

I use power of 5V with amp meter to record their currents.

In LM358N(PDIP) circuit, the current shows 0.7mA and holds for hours.

In LM358 (SOIC-8) circuit, the current begins with 0.7mA same as LM358N,

but a few minutes later the amp meter shows unstable fluctuating value around 25mA to 55mA.

Can you give me some points of difference between LM358 and LM385N.

Best Regards

over 4 years ago

0 kai klaas69 over 4 years ago

Guru 140200 points

Hi Chao,

in your schematic is a mistake. You have swapped pin 4 and pin 8 of IC2:A.

Have you mounted decoupling caps? Have you properly connected the pins of unused OPAmps? Also connect a 100n cap in parallel to R3 and R7.

Kai

0 Ron Michallick over 4 years ago

TI__Guru**** 152026 points

Hello Chao,

Kai is correct, the power is backward on U2. This will create a high supply current and likely damage the op amp.

LM358 is not a rail to rail output, so output voltage of this hysteresis comparator will be roughly 0.6V and 3.6V. LM393 would do better.

Have you read the LM358 application note?

0 Kirby Kruckmeyer96848 over 4 years ago

TI__Genius 17115 points

To answer your question about the different part numbers:

LM358 is the generic part number for the LM358 that originally came from TI. The LM358-N is the generic part number for the LM358 that came from National Semiconductor which TI acquired in 2011. The two products will be very similar with very similar specs, but have different die and manufacturing flows.

LM358N/NOPB is the specific part number for the National part assembled in the PDIP. The NOPB indicates the lead finish is pure tin (Sn) and does not have lead (Pb).

The LM393 will have a similar naming convention.

0 Chao Chang over 4 years ago in reply to kai klaas69

Prodigy 140 points

Dear Kai:

Nice to have your responds.

I have rewire the scheme.

and the output value are truly 0.6~3.6V.

I would do some more researches on LM393.

Best Regards

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Hi Chao,

yes, switching to the LM393 is a good idea.

Good luck :-)

Kai

0 Chao Chang over 4 years ago in reply to kai klaas69

Prodigy 140 points

Dear Sir:

I again did some tests for several LM358 Op-Amps series in different packages.

I found some unreasonable results, please so kind to help me out.

The schematic diagram is shown in half opamp, actual tests on dual channels.

R1&R2 as voltage divider, Non-inverting input is 2.5V

I change the inverting input by switching to 5V or GND and with outputs revealing on Scope.

There were some unexpected results for different chips by observing the Ammeter and Scope.

LM358N(PDIP) and LM358P(PDIP): works great, stable current, signal outputs stable

LM358N(TI) LM358P(TI)
LM358(SOIC-8) and LM358M(SOIC-8): work terrible, unstable current, signal outputs fluctuating

LM358(TI) LM358M(FC)

Sincerely hope you may solve my problem?

I need to implement the SOIC chips on my circuit, but still in trouble.

Best Regards

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Hi Chao,

please add supply decoupling caps.

Kai

0 Ron Michallick over 4 years ago in reply to Chao Chang

TI__Guru**** 152026 points

Chao,

What is on the bottom of your SOIC interface board? Is it shorting out components below it?

0 Chao Chang over 4 years ago in reply to Ron Michallick

Prodigy 140 points

Dear Ron:

I am sure the interface board is absolutely well connected and not shorting with double checking.

I even welded LM358N (PDIP, Motorola) direct on the interface board to test without any problem.

It is very weird to have such unexpected results even I put 10uF capacitor to the power supplier junction.

Best Regards

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Hi Chao,

I'm pretty much sure that the weird results are a consequence of the bread board design with its way too long wirings and stray capacitances.

Please mount a 100nF decoupling cap directly across the supply pins of LM358 and remove the current meter from the supply line. Also, mount a 100R isolation resistor directly at the output pin of LM358. Measure the output voltage of OPAmp behind this isolation resistor. Finally, mount a 100nF filtering cap from pin 2 to pin 4 of LM358, closest to the OPAmp.

Kai

0 Ron Michallick over 4 years ago in reply to Chao Chang

TI__Guru**** 152026 points

Chao,

Are these the same two SOIC op amps that were run with the supply wired backwards? Those op amp are likely broken, try new ones. Otherwise simply the setup, connect just pins 8 and 4 to 5V and ground and measure the current.

0 Chao Chang over 4 years ago in reply to kai klaas69

Prodigy 140 points

Dear Kai:

I am awaiting the arrival of the LM358N (Motolola) in SOP-8 packed marked as LM358D.

I would do the same test as others on interconnection PCB board on LM358D (Motolora).

Thanks to your great advice, if there anything wrong, I would follow your advice and get to you.

Best Regards

Dr. Alex

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Good luck :-)

Kai

0 Chao Chang over 4 years ago in reply to kai klaas69

Prodigy 140 points

Dear Kai:

Those are the tests on the new arrivals of LM358D (ON-SEMI, SOIC8) previously Motolora.

The results are perfect as presumed.

Best Regrads

Chao

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Hi Chao,

do you also have success with the TI's LM358 now?

Kai

0 Chao Chang over 4 years ago in reply to kai klaas69

Prodigy 140 points

Dear Kai:

I always fail on doing the tests of LM358(TI).

Best Regards.

0 kai klaas69 over 4 years ago in reply to Chao Chang

Guru 140200 points

Hi Chao,

then please take a fresh, brand new LM358 and try again. Please also follow the recommendations given in this post:

Kai

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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LM358-N: LM358 vs LM358N