Typical V-in is 8 Volts on S100 bus, but should allow up to 10V. Abs Max current would be 4 Aps (3+1 for the 5V CPU, else 3 Amps). The AMD 5x86 takes up to 1 Amp at 3.3V.
Thanks Tom From: [email protected] [mailto:[email protected]] On Behalf Of Tom Lafleur Sent: Saturday, November 1, 2014 3:18 PM To: [email protected] Subject: Re: [N8VEM-S100:5500] 80386 CPU Board - Component type/value clarification also, what voltage in, voultag out and current max shall I select parts for... S100... 6 to 9V in, I max ?, V set point?? On Sat, Nov 1, 2014 at 3:15 PM, Tom Lafleur <[email protected]> wrote: I use 1% resistor all the time... cheap... nothing special... I will send more info later this weekend when I can looks at my notes... with surface mount resisters and diodes, you can mount them on the back of the board to save room....... On Sat, Nov 1, 2014 at 2:35 PM, John Monahan <[email protected]> wrote: Ok Tom, I’ll take your suggestion. I’ll overlay them in the space as for the 78H05. That way at least for the 5V CPU’s one could use either option. Since you have used these regulators. Could you give me the exact specs (possible part numbers) for the diodes & inductors. I’m a bit worried with the adjustable to get to 3.3V. Always worry that somehow the resistors will go out or range and give an over voltage. Are the resistors special, 1% etc. What wattage. From: [email protected] [mailto:[email protected]] On Behalf Of Tom Lafleur Sent: Saturday, November 1, 2014 1:04 PM To: [email protected] Subject: Re: [N8VEM-S100:5497] 80386 CPU Board - Component type/value clarification the chips are small and so are the parts... so use TWO of them.... also, I always add room for the two trim resisters just in case I want to change the output voltage a bit... On Sat, Nov 1, 2014 at 11:59 AM, John Monahan <[email protected]> wrote: Good point Tom, will switch! In an ideal world I would like to have 5V at say 3-5Amps out, but also 1 -2 Amps at 3.3V for a AMD 5x86 (the Pentium like CPU) Tom mentioned earlier today. Has anybody see a dual output chip – just asking! John From: [email protected] [mailto:[email protected]] On Behalf Of Tom Lafleur Sent: Saturday, November 1, 2014 11:39 AM To: [email protected] Subject: Re: [N8VEM-S100:5492] 80386 CPU Board - Component type/value clarification John... A much better switcher is the LM22677/78, its rated at 5amp, has a very low 100 mOhms output switch (lower heat) and operate at 500Khz or 1Mhz allowing for a much smaller inductor and output C... TI has a number of variants of this part.... The TO263 case is easy to use, I just put a pair of small 4/40 holes under the power pad and solder it from the back side on my prototypes... I use a Bourns inductors and low cost Panasonic output C.. there all surfaces mount, but they are large and very easy to solder... same with the diode... Other part can all be size 1210 or larger parts, again easy to solder... even with my older eyes... If you need 2-4 amp or so, this is the part I use in my designs and I would recommend... There are many other parts like this, but this one is easy to get, simple to use ect.... The LM2576 is rated at 3amp, and switched at 50Khz, requires a very large inductor and very large output C.... tom lafleur On Fri, Oct 31, 2014 at 3:04 PM, John Monahan <[email protected]> wrote: I think I did 4 prototypes on this board Dave, Played around a bit with the caps early on. Did not seem to make a difference (at these low frequencies). The Intel manual has a whole section on board layout. See one page attached here. I ended up with 0.1’s and two 1uF Tants on C71 & C54. Probably more important is the actual power supply. Doing the 80486 I’m learning a lot! On that board I’m bring special wide traces directly to the chip. Also if you can get your hands on one, get a 74H05. There are so many of the 3Amp regulators that are out of specs, it’s ridiculous. While I have a board running at 4.8V’s with one, I really don’t like it. I am also looking into these newer LM2576’s. See attached. Know anything about them. BTW, I’m also doing a direct SMD 32MB RAM daughter board (like our 16MB board). Again a tight board fit (see an non optimized version). I will order 4 for myself but since its completely untested I’m not going to announce it yet. But just FYI. Let me know how the 80386 works. The only thing I’m not comfortable with on that board is the “kludge” to stretch out the pWR* signal. I hope to do it better (clock independent) on this 80486. John From: [email protected] [mailto:[email protected]] On Behalf Of David Fry Sent: Friday, October 31, 2014 2:37 PM To: [email protected] Subject: [N8VEM-S100:5481] 80386 CPU Board - Component type/value clarification Hi John, I am slowly starting to populate my 80386 PCB with capacitors and have a query regarding C51 and C74 (positioned either side of the 80386 CPU). The schematic would suggest that these are 0.1uF multilayer ceramic capacitors like the rest, but the pictures on most versions of your 80386 boards would seem to indicate you have used a tantalum bead capacitor in these two positions. Please can you clarify what type & value of capacitor should be used here. regards and thanks David Fry -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ Tom Lafleur -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ Tom Lafleur -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ Tom Lafleur -- ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ Tom Lafleur -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
