Author Topic: Small footprint USB  (Read 12000 times)

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Offline technixTopic starter

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Small footprint USB
« on: September 14, 2017, 05:23:33 pm »
What is your preferred small footprint, low pin count USB microcontroller? I am thinking about a gadget that can be controlled in my KVM tree and dims an IKEA USB-powered LED lamp. That means the thing needs only USB and a single PWM output. Please refrain from suggesting BGA, CSP or QFN parts.

Candidates (you can add your own:)

* PIC16F1455 in TSOP-14 or SO-14
* ATmega16U2 in TQFP-32
* STM32F042F6P6 in TSOP-20
* Anything else?

Edit: Some additional features I may or may not implement: a full synchronous rectifying buck front end to drive the LED lamp, and ADC feedback resistors for output voltage and current sensing. The intention is to implement digital feedback control to make the light output predictable and calibratable. Should I implement those features those components would be added regardless of MCU:

* A SO-8 complimentary power MOSFET pair AO4606,
* An 1210 power inductor,
* A SOT-23-5 op amp LMV321,
* Four 0603-size resistors,
* One 1812 current sense resistor.
« Last Edit: September 26, 2017, 06:32:36 pm by technix »
 

Offline CM800

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Re: Small footprint USB
« Reply #1 on: September 14, 2017, 05:33:04 pm »
 

Offline JPortici

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Re: Small footprint USB
« Reply #2 on: September 14, 2017, 06:04:35 pm »
PIC16F1455 :-+

-Crystal-less USB
-5V or low voltage available
-Available in 4.4mm TSSOP,soic or even PDIP (why not smaller packages if you want a small gadget?)
-The microchip USB stack example for the 1455 compiles out of the box, take the project and add your own code
-Microchip gives you a free PID for less than 10k units produced

ideally you'll just need the MCU, the usb port and whatever you need on the PWM side
« Last Edit: September 14, 2017, 06:06:51 pm by JPortici »
 
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Online wraper

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Re: Small footprint USB
« Reply #3 on: September 14, 2017, 06:30:34 pm »
EFM8UB11F16G-QSOP24 (I use QFN variants)
Has built in 5V->3,3V 100mA voltage regulator able to supply external load, crysrlal-less USB. Decent IDE with free full Keil compiler licence. Cheap dev boards and debug tools. Free VID/PID given on request.
« Last Edit: September 14, 2017, 06:33:28 pm by wraper »
 

Offline JTR

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Re: Small footprint USB
« Reply #4 on: September 14, 2017, 06:54:53 pm »
I've been using the 16F145x parts but the ATMEL SAM D11 (32-bit ARM M0+) in 14-pins looks so tempting I am thinking of dumping the 16F145x family completely. 
 

Online ataradov

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Re: Small footprint USB
« Reply #5 on: September 14, 2017, 11:25:44 pm »
SAM D11 in 14-pin package for sure. I have lots of simple examples for that thing.
Alex
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #6 on: September 15, 2017, 12:59:16 am »
I've been using the 16F145x parts but the ATMEL SAM D11 (32-bit ARM M0+) in 14-pins looks so tempting I am thinking of dumping the 16F145x family completely.
SAM D11 in 14-pin package for sure. I have lots of simple examples for that thing.

SAM D11 looks like unobtainium to me, hard to find on Taobao and expensive.
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #7 on: September 15, 2017, 01:00:25 am »
EFM8UB11F16G-QSOP24 (I use QFN variants)
Has built in 5V->3,3V 100mA voltage regulator able to supply external load, crysrlal-less USB. Decent IDE with free full Keil compiler licence. Cheap dev boards and debug tools. Free VID/PID given on request.
Does this thing have a TSOP or SOIC version?
 

Online ataradov

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Re: Small footprint USB
« Reply #8 on: September 15, 2017, 01:03:05 am »
SAM D11 looks like unobtainium to me, hard to find on Taobao and expensive.
Well, it is <$1 on DigiKey. I know that there is probably some obscure Chinese MCU, which is even cheaper, but I'll take ARM over that any day of the week.
Alex
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #9 on: September 15, 2017, 01:14:08 am »
SAM D11 looks like unobtainium to me, hard to find on Taobao and expensive.
Well, it is <$1 on DigiKey. I know that there is probably some obscure Chinese MCU, which is even cheaper, but I'll take ARM over that any day of the week.
Maybe I should look for this in some other vendors?

Speaking of, how to write the lightweight USB stack?
 

Online ataradov

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Re: Small footprint USB
« Reply #10 on: September 15, 2017, 01:17:22 am »
Maybe I should look for this in some other vendors?
I'm sure there is a way to get SAM D11 in China. It is would be a huge fail on Atmel/Microchip part if there were not. But I doubt it will be Taobao or Aliexpress.

You may have better luck finding ST chips on those sites, but I'm not familiar with their selection.

Speaking of, how to write the lightweight USB stack?

Here is implementation of the VCP for D11, which is pretty slim - https://github.com/ataradov/vcp
Alex
 
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Offline JTR

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Re: Small footprint USB
« Reply #11 on: September 15, 2017, 06:49:51 am »
Maybe I should look for this in some other vendors?
I'm sure there is a way to get SAM D11 in China. It is would be a huge fail on Atmel/Microchip part if there were not. But I doubt it will be Taobao or Aliexpress.

You may have better luck finding ST chips on those sites, but I'm not familiar with their selection.

Speaking of, how to write the lightweight USB stack?



Here is implementation of the VCP for D11, which is pretty slim - https://github.com/ataradov/vcp

I've just ordered a ATSAMD11-XPRO dev kit from Arrow US for < AUD$37 and that included delivery via FED-EX, Wow! This is a great deal for those of us in Oz/NZ given the price others are asking. 

@ataradov I will look at your VCP implementation. Might be useful. Thanks for sharing.  :-+
 

Online wraper

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Re: Small footprint USB
« Reply #12 on: September 15, 2017, 08:40:06 am »
EFM8UB11F16G-QSOP24 (I use QFN variants)
Has built in 5V->3,3V 100mA voltage regulator able to supply external load, crysrlal-less USB. Decent IDE with free full Keil compiler licence. Cheap dev boards and debug tools. Free VID/PID given on request.
Does this thing have a TSOP or SOIC version?
QSOP24 (0.635mm pin pitch) is largest package available.
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #13 on: September 15, 2017, 11:22:42 am »
Maybe I should look for this in some other vendors?
I'm sure there is a way to get SAM D11 in China. It is would be a huge fail on Atmel/Microchip part if there were not. But I doubt it will be Taobao or Aliexpress.

You may have better luck finding ST chips on those sites, but I'm not familiar with their selection.

Speaking of, how to write the lightweight USB stack?



Here is implementation of the VCP for D11, which is pretty slim - https://github.com/ataradov/vcp

I've just ordered a ATSAMD11-XPRO dev kit from Arrow US for < AUD$37 and that included delivery via FED-EX, Wow! This is a great deal for those of us in Oz/NZ given the price others are asking. 

@ataradov I will look at your VCP implementation. Might be useful. Thanks for sharing.  :-+
China is a different story.
 

Offline langwadt

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Re: Small footprint USB
« Reply #14 on: September 15, 2017, 11:43:32 am »
What is your preferred small footprint, low pin count USB microcontroller? I am thinking about a gadget that can be controlled in my KVM tree and dims an IKEA USB-powered LED lamp. That means the thing needs only USB and a single PWM output. Please refrain from suggesting BGA, CSP or QFN parts.

Candidates (you can add your own:)

* PIC16F1455 in TSOP-14 or SO-14
* ATmega16U2 in TQFP-32
* STM32F042F6P6 in TSOP-20
* Anything else?

for simple and stupid, attiny and v-usb?
 

Online wraper

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Re: Small footprint USB
« Reply #15 on: September 15, 2017, 01:14:15 pm »
for simple and stupid, attiny and v-usb?
It is an option but without any price advantage. Cheapest attiny + 3.3V vreg IC = EFM8 I suggested. Add a crystal and it becomes more expensive. Yes it can be hacked to adjust RC oscillator cal and run crystal-less but is a dubious option and I had bad experience with it. Also needs termination resistors.
 

Offline NorthGuy

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Re: Small footprint USB
« Reply #16 on: September 15, 2017, 01:38:58 pm »
Please refrain from suggesting BGA, CSP or QFN parts.

Why? They have smaller footprint compared to SOIC or even SSOP. For DIY, soldering them is not difficult if you use reflow of even hot air. For outsourced assembly, it probably doesn't matter since they reflow everything.

 

Offline dgtl

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Re: Small footprint USB
« Reply #17 on: September 15, 2017, 07:26:28 pm »
STM32F042 here as well.
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #18 on: September 16, 2017, 02:31:51 am »
Please refrain from suggesting BGA, CSP or QFN parts.

Why? They have smaller footprint compared to SOIC or even SSOP. For DIY, soldering them is not difficult if you use reflow of even hot air. For outsourced assembly, it probably doesn't matter since they reflow everything.
I cannot solder them reliably or inspect them (at least for CSP and BGA) so no. QFN is borderline but soldering and inspection difficulty can still arise.
 

Offline NorthGuy

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Re: Small footprint USB
« Reply #19 on: September 16, 2017, 02:42:33 pm »
I cannot solder them reliably or inspect them (at least for CSP and BGA) so no. QFN is borderline but soldering and inspection difficulty can still arise.

I think it would be more beneficial for you if you learned how to solder them instead of avoiding them. That's where the world is heading, so it'll be nothing else than these small packages somewhere in the near future.
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #20 on: September 16, 2017, 03:36:29 pm »
I cannot solder them reliably or inspect them (at least for CSP and BGA) so no. QFN is borderline but soldering and inspection difficulty can still arise.

I think it would be more beneficial for you if you learned how to solder them instead of avoiding them. That's where the world is heading, so it'll be nothing else than these small packages somewhere in the near future.
I don't think that low pin count BGA would become mainstream. It is a pain to layout, inspect and rework any kind of BGA. The pin density also means that it is necessary to use a 4 or more layers PCB as well as blind or buried vias to fan out the chip properly, both of which are expensive manufacturing processes. There are still a lot of low cost items out there, where even a double layer board can be borderline in the costs. (Hey I live in China, where a lot of those items are made. A 4-layer board is instantly 2x-4x more expensive than a 2-layer one and when you are building down a certain price point you have to stay away from those expensive PCBs.)
 

Offline NorthGuy

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Re: Small footprint USB
« Reply #21 on: September 16, 2017, 04:22:41 pm »
I don't think that low pin count BGA would become mainstream. It is a pain to layout, inspect and rework any kind of BGA. The pin density also means that it is necessary to use a 4 or more layers PCB as well as blind or buried vias to fan out the chip properly, both of which are expensive manufacturing processes. There are still a lot of low cost items out there, where even a double layer board can be borderline in the costs. (Hey I live in China, where a lot of those items are made. A 4-layer board is instantly 2x-4x more expensive than a 2-layer one and when you are building down a certain price point you have to stay away from those expensive PCBs.)

You do need layers to fan out bigger BGA, although it wouldn't be that hard to fan out most of the pin of mid-size BGAs e.g. 100-200 pins on 2-layer board. Small BGAs are not a problem at all.

QFNs are superior to TQFPs or SSOPs because they take less space for the same die size all other things being equal.
 

Offline nctnico

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Re: Small footprint USB
« Reply #22 on: September 16, 2017, 04:45:27 pm »
Please refrain from suggesting BGA, CSP or QFN parts.

Why? They have smaller footprint compared to SOIC or even SSOP. For DIY, soldering them is not difficult if you use reflow of even hot air. For outsourced assembly, it probably doesn't matter since they reflow everything.
I cannot solder them reliably or inspect them (at least for CSP and BGA) so no. QFN is borderline but soldering and inspection difficulty can still arise.
QFN is easy to solder and inspect if you let the pads extend beyond the package and put untented vias in the centre pad.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #23 on: September 16, 2017, 05:24:25 pm »
Please refrain from suggesting BGA, CSP or QFN parts.

Why? They have smaller footprint compared to SOIC or even SSOP. For DIY, soldering them is not difficult if you use reflow of even hot air. For outsourced assembly, it probably doesn't matter since they reflow everything.
I cannot solder them reliably or inspect them (at least for CSP and BGA) so no. QFN is borderline but soldering and inspection difficulty can still arise.
QFN is easy to solder and inspect if you let the pads extend beyond the package and put untented vias in the centre pad.
Maybe I will try this in the near future with a STM32F103TBU6 chip (fairly cheap in China - I don't mind destroying one or two) on a DIY CMSIS-DAP debug probe project (a lot of pins does not need to be fanned out.) I wonder if adding the thermal pad with untented vias would help both soldering and heat dissipation.
« Last Edit: September 16, 2017, 05:39:57 pm by technix »
 

Offline technixTopic starter

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Re: Small footprint USB
« Reply #24 on: September 16, 2017, 05:29:07 pm »
I don't think that low pin count BGA would become mainstream. It is a pain to layout, inspect and rework any kind of BGA. The pin density also means that it is necessary to use a 4 or more layers PCB as well as blind or buried vias to fan out the chip properly, both of which are expensive manufacturing processes. There are still a lot of low cost items out there, where even a double layer board can be borderline in the costs. (Hey I live in China, where a lot of those items are made. A 4-layer board is instantly 2x-4x more expensive than a 2-layer one and when you are building down a certain price point you have to stay away from those expensive PCBs.)

You do need layers to fan out bigger BGA, although it wouldn't be that hard to fan out most of the pin of mid-size BGAs e.g. 100-200 pins on 2-layer board. Small BGAs are not a problem at all.

QFNs are superior to TQFPs or SSOPs because they take less space for the same die size all other things being equal.
Do you have any examples for fanning out a medium sized BGA with a 2-layer board? What is the pin pitch? Things like eMMC doesn't count as for all those pins only 10 or so needed to be fanned out and all the remaining pins are just GND's, VDD's or NC's.

I don't find a lot of QFN packages that does not have a thermal pad. The thermal pad just prevents any routing from being done beneath the chip, forcing a lot more vias and fan out space being added around the chip, negating the benefit of the smaller physical package. For me I have a lot of QFP and SSOP packages that have a substantial amount of routing work beneath the chip, which cannot be converted to QFN without major rework increasing board size.
« Last Edit: September 16, 2017, 05:35:28 pm by technix »
 
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