F405 & F411 versions of the BluePill

What are you developing?
User avatar
RogerClark
Posts: 7541
Joined: Mon Apr 27, 2015 10:36 am
Location: Melbourne, Australia
Contact:

Re: F405 & F411 versions of the BluePill

Post by RogerClark » Fri Dec 08, 2017 10:49 am

The diode is fairly large.

I think I'll need to move the group of components (R's and C's etc) next to pins for B11,B10,B1 to the right
move_components.png
move_components.png (49.25 KiB) Viewed 139 times

User avatar
RogerClark
Posts: 7541
Joined: Mon Apr 27, 2015 10:36 am
Location: Melbourne, Australia
Contact:

Re: F405 & F411 versions of the BluePill

Post by RogerClark » Fri Dec 08, 2017 11:17 am

Can we get the same spec diode in a smaller package, as is a real squeeze getting the it to fit

Or do we need a 1A diode. Will a 500mA one do ?

If I push U4 and a load of the components next to it, to the right, there isnt really enough room, and one of the resistors has to be moved completely out the way, and at the moment I can't see a good place for it.

And its getting too late for me to do any more today.

So I suspect you guys will have it done before I wake up tomorrow ;-)
add_SS12_diode.png
add_SS12_diode.png (107.92 KiB) Viewed 137 times
PS.
I've not pushed any of these changes.

User avatar
Squonk42
Posts: 241
Joined: Thu Dec 29, 2016 9:25 am
Location: Bordeaux, France

Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Fri Dec 08, 2017 12:55 pm

RogerClark wrote:
Fri Dec 08, 2017 11:17 am
Can we get the same spec diode in a smaller package, as is a real squeeze getting the it to fit

Or do we need a 1A diode. Will a 500mA one do ?
This is questionable! We chose the main LDO to be able to deliver 1A, as the STM32F405 already sinks 450 mA max itself; we added some room to power external components as well (SDIO...).

However, the USB 2.0 spec only allows delivering 500 mA, and this is even conditioned by a proper negotiation beforehand, otherwise, it is limited to 100 mA. Despite this limitation, there are a lot of wall adapters with an USB A socket that can deliver more than that, and it is easy to find a USB A to micro USB B cable to power the board over the micro USB B socket.

There are some smaller 1A Schottky diodes, but they are not as common and rather expensive: https://toshiba.semicon-storage.com/inf ... e=CUS10S30

So, do we limit the power supply from the USB to 500 mA? If yes, this one may be interesting:
http://www.onsemi.com/pub/Collateral/MBR0520LT1-D.PDF
https://www.aliexpress.com/item/sku/1985290956.html

racemaniac
Posts: 656
Joined: Sat Nov 07, 2015 9:09 am

Re: F405 & F411 versions of the BluePill

Post by racemaniac » Fri Dec 08, 2017 1:35 pm

Squonk42 wrote:
Fri Dec 08, 2017 12:55 pm
RogerClark wrote:
Fri Dec 08, 2017 11:17 am
Can we get the same spec diode in a smaller package, as is a real squeeze getting the it to fit

Or do we need a 1A diode. Will a 500mA one do ?
This is questionable! We chose the main LDO to be able to deliver 1A, as the STM32F405 already sinks 450 mA max itself; we added some room to power external components as well (SDIO...).

However, the USB 2.0 spec only allows delivering 500 mA, and this is even conditioned by a proper negotiation beforehand, otherwise, it is limited to 100 mA. Despite this limitation, there are a lot of wall adapters with an USB A socket that can deliver more than that, and it is easy to find a USB A to micro USB B cable to power the board over the micro USB B socket.

There are some smaller 1A Schottky diodes, but they are not as common and rather expensive: https://toshiba.semicon-storage.com/inf ... e=CUS10S30

So, do we limit the power supply from the USB to 500 mA? If yes, this one may be interesting:
http://www.onsemi.com/pub/Collateral/MBR0520LT1-D.PDF
https://www.aliexpress.com/item/sku/1985290956.html
how about this one:
https://www.aliexpress.com/item/100PCS- ... eLevelAB=0
http://www.mouser.com/ds/2/258/B5817W-B ... 276623.pdf

Same package as the 0.5A you're mentioning, but also 1A (and bit lower votlage drop)

User avatar
Squonk42
Posts: 241
Joined: Thu Dec 29, 2016 9:25 am
Location: Bordeaux, France

Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Fri Dec 08, 2017 1:48 pm

racemaniac wrote:
Fri Dec 08, 2017 1:35 pm
how about this one:
https://www.aliexpress.com/item/100PCS- ... eLevelAB=0
http://www.mouser.com/ds/2/258/B5817W-B ... 276623.pdf

Same package as the 0.5A you're mentioning, but also 1A (and bit lower votlage drop)
There is something I don't understand in the datasheet: max dissipation is 250mW, however Vf is max 0.45V x 1A = 450mW to dissipate.. Tj 25°C !?!

racemaniac
Posts: 656
Joined: Sat Nov 07, 2015 9:09 am

Re: F405 & F411 versions of the BluePill

Post by racemaniac » Fri Dec 08, 2017 2:34 pm

Squonk42 wrote:
Fri Dec 08, 2017 1:48 pm
racemaniac wrote:
Fri Dec 08, 2017 1:35 pm
how about this one:
https://www.aliexpress.com/item/100PCS- ... eLevelAB=0
http://www.mouser.com/ds/2/258/B5817W-B ... 276623.pdf

Same package as the 0.5A you're mentioning, but also 1A (and bit lower votlage drop)
There is something I don't understand in the datasheet: max dissipation is 250mW, however Vf is max 0.45V x 1A = 450mW to dissipate.. Tj 25°C !?!
hmm, indeed pretty strange >_<
also don't get it O_o

racemaniac
Posts: 656
Joined: Sat Nov 07, 2015 9:09 am

Re: F405 & F411 versions of the BluePill

Post by racemaniac » Fri Dec 08, 2017 2:57 pm

these ones are probably pretty much perfect, but way too expensive -_-
https://www.aliexpress.com/wholesale?ca ... xt=LTC4357

User avatar
Squonk42
Posts: 241
Joined: Thu Dec 29, 2016 9:25 am
Location: Bordeaux, France

Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Fri Dec 08, 2017 3:40 pm

This one is a true 1A 450mV AND 450mW in a slightly smaller (small enough?) package (3.85 x 1.70 mm including pins):
https://www.diodes.com/assets/Datasheets/ds30217.pdf
https://www.aliexpress.com/item/sku/32841683463.html

racemaniac
Posts: 656
Joined: Sat Nov 07, 2015 9:09 am

Re: F405 & F411 versions of the BluePill

Post by racemaniac » Fri Dec 08, 2017 4:13 pm

seeing rogers screenshot, i'm wondering if we can't tweak the footprint a bit with slightly smaller pads. it's probably a bit worse, but if you see the 3d model on them, they're quite a bit bigger than they need to be.

User avatar
Squonk42
Posts: 241
Joined: Thu Dec 29, 2016 9:25 am
Location: Bordeaux, France

Re: F405 & F411 versions of the BluePill

Post by Squonk42 » Fri Dec 08, 2017 6:15 pm

I don't know if it is a good idea, since the thermal characteristics are already given when PCB mounted with 0.2" x 0.2" (5.0 mm x 5.0 mm) copper pad areas...

Post Reply