On Tue, 24 Jan 2023 11:37:00 -0800 (PST), Ricky <gnuarm.deletethisbit@gmail.com> wrote:>I've always used 0603 (1608 metric) size passives as the minimum size in my designs to optimize manufacturing. I'm told the smaller the part, the more likely it is to tombstone, stand up with only one end soldered. > >The common sizes below 0603 seem to be 0402 and 0201. 0402 would not seem to have a big size reduction, but if it's an advantage without penalty, why not take it. 0201 is much smaller, but I wonder about how well it would work. > >What sizes do you use, smaller than 0603? How much trouble do you have with them?We use 0603 as our smallest, too. Sometimes I would like to use smaller but we rarely do. If so, we place smaller parts, usually smaller that 19 mil pitch ICs by hand. What I am hearing from vendor(s) is that 0603 and larger parts will not be increasing production for those sizes. Not getting rid of them but just not increasing production scaling. I hope we can get newer machines before we have to eventually go to 0402 or 0201 etc. boB
Easily Assembled Passive Component Sizes
Started by ●January 24, 2023
Reply by ●January 25, 20232023-01-25
Reply by ●January 25, 20232023-01-25
On Wed, 25 Jan 2023 12:05:47 -0700, boB <boB@K7IQ.com> wrote:>On Tue, 24 Jan 2023 11:37:00 -0800 (PST), Ricky ><gnuarm.deletethisbit@gmail.com> wrote: > >>I've always used 0603 (1608 metric) size passives as the minimum size in my designs to optimize manufacturing. I'm told the smaller the part, the more likely it is to tombstone, stand up with only one end soldered. >> >>The common sizes below 0603 seem to be 0402 and 0201. 0402 would not seem to have a big size reduction, but if it's an advantage without penalty, why not take it. 0201 is much smaller, but I wonder about how well it would work. >> >>What sizes do you use, smaller than 0603? How much trouble do you have with them? > > >We use 0603 as our smallest, too. Sometimes I would like to use >smaller but we rarely do. If so, we place smaller parts, usually >smaller that 19 mil pitch ICs by hand.We just got a new Yamaha p+p that can do really small stuff.> >What I am hearing from vendor(s) is that 0603 and larger parts will >not be increasing production for those sizes. Not getting rid of >them but just not increasing production scaling. > >I hope we can get newer machines before we have to eventually go to >0402 or 0201 etc. > >boBSome parts need to dissipate power. We use resistors in 1206, 2010, 2512, DPAK, and big wirewounds. I use 0805 by default in not-very-dense boards. It's hard to probe really tiny parts. https://www.dropbox.com/s/8oefk1v8avr6l7a/Probe_Slips.jpg?raw=1
Reply by ●January 25, 20232023-01-25
On 1/24/23 11:37 AM, Ricky wrote:> I've always used 0603 (1608 metric) size passives as the minimum size in my designs to optimize manufacturing. I'm told the smaller the part, the more likely it is to tombstone, stand up with only one end soldered. > > The common sizes below 0603 seem to be 0402 and 0201. 0402 would not seem to have a big size reduction, but if it's an advantage without penalty, why not take it. 0201 is much smaller, but I wonder about how well it would work. > > What sizes do you use, smaller than 0603? ...I've used down to 0201, mainly when there were no other variants available such as with very high speed sampling diodes. Generally, like others here, I stick with 0603 but when board space is at a premium then 0402 is my standard.> ... How much trouble do you have with them? >None. Tombstoning isn't much of a problem in a well-run reflow soldering process. I also have not noticed an increase in issues with smaller sizes of discretes. Large QFP sometimes produced solder shorts but that was usually related to screeding on too much paste. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●January 25, 20232023-01-25
onsdag den 25. januar 2023 kl. 13.51.19 UTC+1 skrev Ricky:> On Wednesday, January 25, 2023 at 5:09:27 AM UTC-5, Jan Panteltje wrote: > > On a sunny day (Wed, 25 Jan 2023 00:10:18 -0800 (PST)) it happened John > > Walliker <jrwal...@gmail.com> wrote in > > <53941776-1d15-4d47...@googlegroups.com>: > > >On Tuesday, 24 January 2023 at 21:06:01 UTC, Ricky wrote: > > > > > >> I'm looking at replacing some op amps that can't be bought with a class D > > >speaker driver chip. Seems to quell the high frequency noise, they indicate > > >significant inductors. They go up in value with higher impedance loads for > > >some reason. They have 33 uH with an 8 ohm load, so I'm worried I'd need hundreds > > >of uH for a 50 ohm load. One on each of four outputs would be a bit > > >much. So I'm looking at shrinking everything else I can. > > > > > >A balanced filter with a pair of 33uH inductors driving an 8 ohm resistive load > > >will > > >have a low-pass corner frequency of about 19kHz. A higher load resistance > > >will > > >need more inductance to get the same corner frequency. > > >John > > I do not like the switching audio amps, killed an ebay one once, > > rest frequency feedthrough after filter? > > > > I build a real analog one around the TDA7924 >20 years ago, > > is still working great (on about 12/7) > > and those are still available on ebay: > > https://www.ebay.com/itm/162149310109 > > > > Best audio power chip I have ever seen: > > http://panteltje.com/panteltje/amplifier/index.html > Not trying to drive 8 ohms, not trying to drive many watts. Just trying to drive 50 ohms, single ended and 600 ohms differential. The entire board is not much larger than the devices you are talking about, 115 mm x 23 mm x ~ 10 mm. > > The main point of using the audio amp chip, is they replace three dual op amp chips, 3 x 5 mm each. But as it turns out, the original design was pretty optimal for the requirements. I used positive feedback with a small output resistor (12.1 ohms) to generate a 50 ohm output. Works the champ. I just can't get the LM8272MM due to the chip shortage and it's not getting any easier yet. > > Know any other MSOP8 dual op amps that can source/sink 100 mA? I can't find any. This one drives capacitive loads well too.what voltage? rail-rail-rail? the output resistor should make capacitive loads less of an issue
Reply by ●January 26, 20232023-01-26
On Wednesday, January 25, 2023 at 4:10:23 AM UTC-4, John Walliker wrote:> On Tuesday, 24 January 2023 at 21:06:01 UTC, Ricky wrote: > > > I'm looking at replacing some op amps that can't be bought with a class D speaker driver chip. Seems to quell the high frequency noise, they indicate significant inductors. They go up in value with higher impedance loads for some reason. They have 33 uH with an 8 ohm load, so I'm worried I'd need hundreds of uH for a 50 ohm load. One on each of four outputs would be a bit much. So I'm looking at shrinking everything else I can. > A balanced filter with a pair of 33uH inductors driving an 8 ohm resistive load > will have a low-pass corner frequency of about 19kHz. A higher load resistance > will need more inductance to get the same corner frequency.While on the plane, I realized what is wrong with your statement. First, the output filter is LC, not RL, which makes a huge difference. This filter is not the low pass for the audio as such. It is a low pass to filter the 400 kHz noise. So the exact corner is not important, other than being well below 400 kHz, and in fact, should not be too close to 20 kHz, so as to not over attenuate the anti-alias filter on the DAC. I did some calculations for a 40 kHz corner frequency and got an LC product of 16E-12. What remains is to decide how to apportion that product to each component. Taking a square root gives 4 uF and 4 uH as a starting point. The reactance of each component at 20 kHz (the highest audio component of interest) is 0.5 ohms for the inductor and 2 ohms for the capacitor. So this circuit will not be compromised by the 50 ohm load. Even an 8 ohm load would have much impact. My goal is to reduce the size of the inductor, since there are four of them. This lowers the impedance of both the cap and inductor further, making the load less significant. However, the load on the amp needs to be considered. The above 4 uF/4 uH filter, produces 1.5 ohm load (per side) on the amp output. That's not so good. So I will need to increase the inductance and reduce the capacitance to get a higher impedance load for the amp output. So maybe a 10 uH inductor and a 1.5 uF cap? It gives 4 ohms load to the amp output at 20 kHz. 15 uH and 1 uF gives 6 ohms. -- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Reply by ●January 26, 20232023-01-26
On Wednesday, January 25, 2023 at 4:11:21 PM UTC-4, lang...@fonz.dk wrote:> onsdag den 25. januar 2023 kl. 13.51.19 UTC+1 skrev Ricky: > > On Wednesday, January 25, 2023 at 5:09:27 AM UTC-5, Jan Panteltje wrote: > > > On a sunny day (Wed, 25 Jan 2023 00:10:18 -0800 (PST)) it happened John > > > Walliker <jrwal...@gmail.com> wrote in > > > <53941776-1d15-4d47...@googlegroups.com>: > > > >On Tuesday, 24 January 2023 at 21:06:01 UTC, Ricky wrote: > > > > > > > >> I'm looking at replacing some op amps that can't be bought with a class D > > > >speaker driver chip. Seems to quell the high frequency noise, they indicate > > > >significant inductors. They go up in value with higher impedance loads for > > > >some reason. They have 33 uH with an 8 ohm load, so I'm worried I'd need hundreds > > > >of uH for a 50 ohm load. One on each of four outputs would be a bit > > > >much. So I'm looking at shrinking everything else I can. > > > > > > > >A balanced filter with a pair of 33uH inductors driving an 8 ohm resistive load > > > >will > > > >have a low-pass corner frequency of about 19kHz. A higher load resistance > > > >will > > > >need more inductance to get the same corner frequency. > > > >John > > > I do not like the switching audio amps, killed an ebay one once, > > > rest frequency feedthrough after filter? > > > > > > I build a real analog one around the TDA7924 >20 years ago, > > > is still working great (on about 12/7) > > > and those are still available on ebay: > > > https://www.ebay.com/itm/162149310109 > > > > > > Best audio power chip I have ever seen: > > > http://panteltje.com/panteltje/amplifier/index.html > > Not trying to drive 8 ohms, not trying to drive many watts. Just trying to drive 50 ohms, single ended and 600 ohms differential. The entire board is not much larger than the devices you are talking about, 115 mm x 23 mm x ~ 10 mm. > > > > The main point of using the audio amp chip, is they replace three dual op amp chips, 3 x 5 mm each. But as it turns out, the original design was pretty optimal for the requirements. I used positive feedback with a small output resistor (12.1 ohms) to generate a 50 ohm output. Works the champ. I just can't get the LM8272MM due to the chip shortage and it's not getting any easier yet. > > > > Know any other MSOP8 dual op amps that can source/sink 100 mA? I can't find any. This one drives capacitive loads well too. > what voltage? rail-rail-rail? the output resistor should make capacitive loads less of an issueVoltage? ±12 is the max. The op amp is only on the +12 supply because the -12 is pretty lame. My target is to single ended drive a 50 ohm load with a 5Vpp sine wave, 6Vpp if I can. We also have to drive 600 ohm differential loads, and I need to switch in a pair of 300 ohm resistors I suppose. I think that is a much lower voltage, 0dBm. When I do the math, I get 0.775Vrms or 2.2Vpp. I don't think that's going to be a problem. This drives cables and I'm not aware of any restriction on the length. -- Rick C. +- Get 1,000 miles of free Supercharging +- Tesla referral code - https://ts.la/richard11209
Reply by ●January 26, 20232023-01-26
On a sunny day (Wed, 25 Jan 2023 20:20:15 -0800 (PST)) it happened Ricky <gnuarm.deletethisbit@gmail.com> wrote in <938ee9a8-d571-4a33-a289-3cd8af005054n@googlegroups.com>:>Voltage? =C2=B112 is the max. The op amp is only on the +12 supply because >the -12 is pretty lame. My target is to single ended drive a 50 ohm load >with a 5Vpp sine wave, 6Vpp if I can. > >We also have to drive 600 ohm differential loads, and I need to switch in a >pair of 300 ohm resistors I suppose. I think that is a much lower voltage, >0dBm. When I do the math, I get 0.775Vrms or 2.2Vpp. I don't think that's >going to be a problem. > >This drives cables and I'm not aware of any restriction on the length.Apart from the chip size, 2 x LM380 will give enough power on 12V. There exist many audio cable driver chips... used those, cannot remember type numbers.. ask in audio group or google.. Things like noise etc count there too.
