LH0070 / LM169 - die pictures - Page 1
Forum section: electronics / general

author: Noopy
author_rank: Super Contributor
timestamp: April 06, 2020, 08:31:57 pm
content: Hi all!I got a LH0070, a 10V-reference built by National Semiconductor:A ceramic-@*#+%? ...I don´t know what is the english name for "Keramikträger".There is a 56Ohm-resistor and a 3,6nF-capacitor in series at the output. It seems that the reference was unstable at higher frequencies and they had to damp it.Hey, it´s a LM169! A reference that is a bit more accurate.Does anybody know what that is? There is a fusible link but what is the big thing consisting out of two parts connected unter a metal block?More pictures here:https://richis-lab.de/REF09.htm

author: iMo
author_rank: Super Contributor
timestamp: April 06, 2020, 09:08:10 pm
content: "keramikträger" == "ceramic substrate" ?

author: Noopy
author_rank: Super Contributor
timestamp: April 06, 2020, 09:11:10 pm
content: Quote from: imo on April 06, 2020, 09:08:10 pmYes! Thanks!In fact in german also "Keramiksubstrat" is possible... Well too late for today...

author: edavid
author_rank: Super Contributor
timestamp: April 06, 2020, 09:11:57 pm
content: Quote from: Noopy on April 06, 2020, 08:31:57 pmEnglish speaking electronics engineers would call that a "thick film hybrid circuit".

author: Noopy
author_rank: Super Contributor
timestamp: April 06, 2020, 09:13:20 pm
content: Quote from: edavid on April 06, 2020, 09:11:57 pmYes, also right!Perhaps more right.

author: iMo
author_rank: Super Contributor
timestamp: April 06, 2020, 09:40:16 pm
content: "Thick film hybrid integrated circuits" are usually built on a "ceramic substrate"

author: Theboel
author_rank: Frequent Contributor
timestamp: April 07, 2020, 03:01:36 am
content: Hi,stupid question Is this a good reference ?I have some I pull out from old board

author: Noopy
author_rank: Super Contributor
timestamp: April 07, 2020, 03:21:11 am
content: Good morning!It is a ceramic substrate with a thick film resistor but there are also ceramic Substrates with thin film resistors!Because of that I usually use "ceramic substrate" that´s alway correct.Quote from: Theboel on April 07, 2020, 03:01:36 amWell, good, better, good enough… In my view it´s good. A voltnut would prefer a LTZ1000.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 07, 2020, 07:33:07 am
content: It is a while I looked at it. AFAIR it is a relatively good one. Roughly comparable to LT1031 or AD581 in a metal case.

author: Noopy
author_rank: Super Contributor
timestamp: April 07, 2020, 09:43:44 am
content: A moment ago I learned that the ceramic substrate is no surprise: LH stands for Linear Hybrid!

author: Lemonizer
author_rank: Regular Contributor
timestamp: April 07, 2020, 10:00:43 am
content: Noopy, those are really nice pictures ! Thanks for that, makes me want to get a microscope sometimesCeramic caps/components got a bad characteristic for such voltage reference ? I don't know much about them, but I'm quite interested.I do have a LM399 board I bought online, that I'm using as a sanity check for my various DMM's. I'd love to build a few myself in the future !

author: Noopy
author_rank: Super Contributor
timestamp: April 07, 2020, 10:48:36 am
content: Thank you!There are a lot of different types of ceramic caps. You can also buy very good ceramic caps.But I don´t think that is a problem here. The RC doesn´t stabilize the voltage it musst only short the output if the frequency gets to high. That´s a very easy task.

author: edavid
author_rank: Super Contributor
timestamp: April 07, 2020, 02:07:29 pm
content: Quote from: Noopy on April 07, 2020, 09:43:44 amI suspect there was an earlier version with more than one IC on the hybrid, before they integrated it into the LM169.

author: schmitt trigger
author_rank: Super Contributor
timestamp: April 07, 2020, 02:21:26 pm
content: Noopy;thanks again for taking us to the wonderful world of micro electronics.Back when National Semi was a major player, their prefixes in their part numbers made a lot of sense:LM= Linear MonolithicLH= Linear HybridDM= Digital MonolithicLF= Linear FetLMC= Linear Monolithic CMOSAnd so on.I read somewher that this was a carryover from Fairchild with theiruA = micro analog prefixes.

author: Noopy
author_rank: Super Contributor
timestamp: April 07, 2020, 02:39:23 pm
content: Quote from: edavid on April 07, 2020, 02:07:29 pmSounds reasonable!Quote from: schmitt trigger on April 07, 2020, 02:21:26 pmThanks!

author: kleiner Rainer
author_rank: Regular Contributor
timestamp: April 07, 2020, 04:26:24 pm
content: If you look at the datasheet of most regulators/references you will find that the output impedance is rising with frequency. This means the output impedance is inductive. Depending on load and output capacitor size, you get a nice noise voltage bump at the resonance frequency of the resulting series LC circuit. One way to mitigate this is to put a resistor in series with the cap and destroy the Q of the LC circuit. I suspect this is the case here.Greetings,Rainer

author: edavid
author_rank: Super Contributor
timestamp: April 07, 2020, 06:02:52 pm
content: Quote from: kleiner Rainer on April 07, 2020, 04:26:24 pmNot exactly - the explanation is on the LM169 datasheet:Quote

author: kleiner Rainer
author_rank: Regular Contributor
timestamp: April 07, 2020, 06:56:18 pm
content: I had this text in mind:https://electrooptical.net/static/oldsite/www/sed/ErrolDietzRegulatorNoisePeaks.pdfCould be useful if you need a low noise reference (or low noise in a certain frequency range).Greetings,Rainer