PWM controllers... shopping

[bitrex]

On 4/11/2020 2:11 PM, Winfield Hill wrote:

bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?

I mean "retirement" in the sense of having enough money to still afford
food and a place to live when I can't work a full 70 hours a week in the
year 2050 and thereby avoid the wrath of whatever fashion of bipedal
jackal-headed Egyptian God-emperor, sentient gaseous nebula the size of
the Solar system, or "benevolent" quantum artificial intelligence that
rules Earth circa the year 2050.

 

[sea moss]

Here are some starters, plus bonus memes:
https://imgur.com/gallery/M1S0DbI

MC34063 is a hysteretic controller, and not even a good one at that. The CS
pin reduces oscillator frequency in an odd way.
Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

Thanks for that link, Tim. Nothing warms my heart like seeing a meme about an IC. Also I hadn't realized the MC34063 is hysteretic. I'll make sure I check out the chips you mention in that blog post.

 

[sea moss]

I guess the big question is, what are you wanting to do with the
controller ?
snip

boB

I am driving a thermoelectric cooler with an H-bridge configuration (inductor in series with the TEC). So I need to drive 4 switches, but really only need one PWM signal and its inverse.

Since there are only so many PWM controllers with 4 outputs (and 2 of them for driving high-side switches), I will likely need an external gate driver IC. Also, I need to be able to drive the reference pin with the temperature setpoint, and the majority of PWM controllers don't allow for external reference. This is what led me down the path of "you know what I'll just find the simplest possible PWM block and do the rest myself"

Also, yeah I have used the UCx84x family a bit too. I might end up using one of those at the end of the day.

This is for work, so it could end up in production for many years.

 

[sea moss]

On Friday, April 10, 2020 at 7:03:08 PM UTC-7, Ricky C wrote:

On Friday, April 10, 2020 at 8:25:46 PM UTC-4, sea moss wrote:
I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

You would need an FPGA with an ADC input. If you already had one on the board, then you could get this PWM block for free.

Oh, how would that work?

You can construct an ADC in any FPGA with differential inputs which is pretty much all of them.

--

Rick C.

You would generate a timer in the FPGA (digital version of the ramp waveform), and compare it to the digitized input from your error amp.

 

[sea moss]

You can make a decent analog-to-PWM converter with an RRIO opamp or
comparator and a cap and three resistors.

--

John Larkin Highland Technology, Inc

This might be the bare-bones solution I was looking for. I'll give it a whirl.

 

[Lasse Langwadt Christense]

lørdag den 11. april 2020 kl. 02.10.07 UTC+2 skrev bitrex:

On 4/10/2020 7:59 PM, Ricky C wrote:
On Friday, April 10, 2020 at 7:19:36 PM UTC-4, sea moss wrote:
Seems like every time I start a new power design, I waste a bunch of time looking for the ideal PWM controller.

At the end of the day I'd really like to have the simplest IC possible to handle just the PWM function, and I provide my own error amp, gate driver, and reference externally. The ideal part would look like this: oscillator set by resistor, comparator non-inverting input, and pulse out. Plus Vdd and ground equals 5 pins only! Does anything like this exist?

I've also been checking out the famous TL494, and MC34063 since I have never used them. Does anyone here have horror stories from these parts that I can't infer from the datasheets?

Another one I discovered is MCP1632, pretty simple but not quite what I'm looking for. Vdd=6V max for example, kind of sucks. I do like how they use a 50uA current source as the reference pin, so you set Vref with a resistor or drive from low-impedance source, nice.
http://ww1.microchip.com/downloads/en/DeviceDoc/20005254A.pdf

I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

There's not much in the control world that can't be done primarily digitally these days.


ATTiny13A, 1k program memory, two PWM channels, 10 bit ADC, 20MHz clock.
can do all sorts of stuff with that for 40 cent in 100s

https://www.st.com/en/motor-drivers/stspin32f0a.html

48MHz Cortex-M0, 3x opamp, comparator, 3*halfbridge gatedriver, buck converter

 

[sea moss]

https://www.st.com/en/motor-drivers/stspin32f0a.html

48MHz Cortex-M0, 3x opamp, comparator, 3*halfbridge gatedriver, buck converter

Cool part. Vdd up to 45V. Integrated bootstrap diodes, nice.

 

[Lasse Langwadt Christense]

søndag den 12. april 2020 kl. 01.17.41 UTC+2 skrev sea moss:

https://www.st.com/en/motor-drivers/stspin32f0a.html

48MHz Cortex-M0, 3x opamp, comparator, 3*halfbridge gatedriver, buck converter

Cool part. Vdd up to 45V. Integrated bootstrap diodes, nice.

for a one-of you can get a a ~$30 dev board

https://www.digikey.dk/product-detail/da/stmicroelectronics/STEVAL-ESC002V1/497-18362-ND/9826047

 

[Ricky C]

On Saturday, April 11, 2020 at 2:20:12 PM UTC-4, Lasse Langwadt Christensen wrote:

lørdag den 11. april 2020 kl. 20.12.06 UTC+2 skrev Winfield Hill:
bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?


a lot of people used to working and the mental exercise that
comes with it, wither and die surprisingly fast after they retire

Sounds very anecdotal...

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Ricky C]

On Saturday, April 11, 2020 at 3:44:13 PM UTC-4, sea moss wrote:

On Friday, April 10, 2020 at 7:03:08 PM UTC-7, Ricky C wrote:
On Friday, April 10, 2020 at 8:25:46 PM UTC-4, sea moss wrote:
I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

You would need an FPGA with an ADC input. If you already had one on the board, then you could get this PWM block for free.

Oh, how would that work?

You can construct an ADC in any FPGA with differential inputs which is pretty much all of them.

--

Rick C.

You would generate a timer in the FPGA (digital version of the ramp waveform), and compare it to the digitized input from your error amp.

I thought you were saying if there were an ADC on the board you wouldn't need the FPGA. The only real shining star of using the FPGA is that it allows virtually any algorithm to be implemented. Analog has a lot of restrictions in that department and you are left with little room for customization once the board is designed.

From the way people are describing this I don't think an FPGA is needed. A simple CPLD could be used I'm sure, but then you would need a separate ADC.. You can get a lot of capability in a $3 part.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Lasse Langwadt Christense]

søndag den 12. april 2020 kl. 03.24.33 UTC+2 skrev Ricky C:

On Saturday, April 11, 2020 at 3:44:13 PM UTC-4, sea moss wrote:
On Friday, April 10, 2020 at 7:03:08 PM UTC-7, Ricky C wrote:
On Friday, April 10, 2020 at 8:25:46 PM UTC-4, sea moss wrote:
I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

You would need an FPGA with an ADC input. If you already had one on the board, then you could get this PWM block for free.

Oh, how would that work?

You can construct an ADC in any FPGA with differential inputs which is pretty much all of them.

--

Rick C.

You would generate a timer in the FPGA (digital version of the ramp waveform), and compare it to the digitized input from your error amp.

I thought you were saying if there were an ADC on the board you wouldn't need the FPGA. The only real shining star of using the FPGA is that it allows virtually any algorithm to be implemented. Analog has a lot of restrictions in that department and you are left with little room for customization once the board is designed.

From the way people are describing this I don't think an FPGA is needed. A simple CPLD could be used I'm sure, but then you would need a separate ADC. You can get a lot of capability in a $3 part.

if the performance isn't too critical and there's a comparator available, like an LVDS input, you can make simple delta-sigma ADC

 

[Ricky C]

On Saturday, April 11, 2020 at 10:11:14 PM UTC-4, Lasse Langwadt Christensen wrote:

søndag den 12. april 2020 kl. 03.24.33 UTC+2 skrev Ricky C:
On Saturday, April 11, 2020 at 3:44:13 PM UTC-4, sea moss wrote:
On Friday, April 10, 2020 at 7:03:08 PM UTC-7, Ricky C wrote:
On Friday, April 10, 2020 at 8:25:46 PM UTC-4, sea moss wrote:
I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

You would need an FPGA with an ADC input. If you already had one on the board, then you could get this PWM block for free.

Oh, how would that work?

You can construct an ADC in any FPGA with differential inputs which is pretty much all of them.

--

Rick C.

You would generate a timer in the FPGA (digital version of the ramp waveform), and compare it to the digitized input from your error amp.

I thought you were saying if there were an ADC on the board you wouldn't need the FPGA. The only real shining star of using the FPGA is that it allows virtually any algorithm to be implemented. Analog has a lot of restrictions in that department and you are left with little room for customization once the board is designed.

From the way people are describing this I don't think an FPGA is needed.. A simple CPLD could be used I'm sure, but then you would need a separate ADC. You can get a lot of capability in a $3 part.


if the performance isn't too critical and there's a comparator available, like an LVDS input, you can make simple delta-sigma ADC

Yes, I mentioned that nearly all FPGAs have differential inputs. But most CPLDs do not, at least not any I know of. But then I don't look at CPLDs so hard. They are typically below my radar. They get very complicated and expensive as the size gets up even slightly. They also are typically designed for simple functions with many outputs. FPGAs are weighted for more internal logic per output and more recently there are some available with an adequate amount of logic in lower pin count packages. By "more recently" I mean the last decade or so.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[boB]

On Sat, 11 Apr 2020 14:20:17 -0400, bitrex <user@example.net> wrote:

On 4/11/2020 2:11 PM, Winfield Hill wrote:
bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?



I mean "retirement" in the sense of having enough money to still afford
food and a place to live when I can't work a full 70 hours a week in the
year 2050 and thereby avoid the wrath of whatever fashion of bipedal
jackal-headed Egyptian God-emperor, sentient gaseous nebula the size of
the Solar system, or "benevolent" quantum artificial intelligence that
rules Earth circa the year 2050.

I cannot see me "retiring" from electronics. Only freeing my time up
to do things I want to do. I don't think I will be around by 2050,
or at least be able to hold on to a soldering iron.

Maybe, if I am successful at "retirement", I can hire a couple of
technicians to help me build circuits that I have always wanted to
build ! Dream products !

boB

 

[bitrex]

On 4/12/2020 12:42 AM, boB wrote:

On Sat, 11 Apr 2020 14:20:17 -0400, bitrex <user@example.net> wrote:

On 4/11/2020 2:11 PM, Winfield Hill wrote:
bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?



I mean "retirement" in the sense of having enough money to still afford
food and a place to live when I can't work a full 70 hours a week in the
year 2050 and thereby avoid the wrath of whatever fashion of bipedal
jackal-headed Egyptian God-emperor, sentient gaseous nebula the size of
the Solar system, or "benevolent" quantum artificial intelligence that
rules Earth circa the year 2050.


I cannot see me "retiring" from electronics. Only freeing my time up
to do things I want to do. I don't think I will be around by 2050,
or at least be able to hold on to a soldering iron.

Maybe, if I am successful at "retirement", I can hire a couple of
technicians to help me build circuits that I have always wanted to
build ! Dream products !

boB

No, I don't expect I'll ever stop doing it, that aspect was unclear to
me when I started fiddling with transistors in my early 20s but in my
early 40s it's become clear I'll be doing this in some capacity as long
as I can. But I'm even now, not as young and energetic as I used to be
and how long I can do it for pay is a question.

Age-ism in the tech field is real (as it is in many fields) and even at
40 on the software-side at least I'm the "old man" and Granpa already.
Age-ism seems to be the last socially acceptable form of bigotry and you
can see it lots of places and I'm guilty of it from time to time myself,
ok, boomer?

That most of my friends and family don't see the appeal or understand
what it's all about doesn't bother me much it's not the kind of stuff
you can post about on Facebook and expect dozens of "likes" like a woman
in her underwear. Oh well.

 

[boB]

On Sun, 12 Apr 2020 00:57:06 -0400, bitrex <user@example.net> wrote:

On 4/12/2020 12:42 AM, boB wrote:
On Sat, 11 Apr 2020 14:20:17 -0400, bitrex <user@example.net> wrote:

On 4/11/2020 2:11 PM, Winfield Hill wrote:
bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?



I mean "retirement" in the sense of having enough money to still afford
food and a place to live when I can't work a full 70 hours a week in the
year 2050 and thereby avoid the wrath of whatever fashion of bipedal
jackal-headed Egyptian God-emperor, sentient gaseous nebula the size of
the Solar system, or "benevolent" quantum artificial intelligence that
rules Earth circa the year 2050.


I cannot see me "retiring" from electronics. Only freeing my time up
to do things I want to do. I don't think I will be around by 2050,
or at least be able to hold on to a soldering iron.

Maybe, if I am successful at "retirement", I can hire a couple of
technicians to help me build circuits that I have always wanted to
build ! Dream products !

boB



No, I don't expect I'll ever stop doing it, that aspect was unclear to
me when I started fiddling with transistors in my early 20s but in my
early 40s it's become clear I'll be doing this in some capacity as long
as I can. But I'm even now, not as young and energetic as I used to be
and how long I can do it for pay is a question.

Age-ism in the tech field is real (as it is in many fields) and even at
40 on the software-side at least I'm the "old man" and Granpa already.
Age-ism seems to be the last socially acceptable form of bigotry and you
can see it lots of places and I'm guilty of it from time to time myself,
ok, boomer?

I'm 65 (a boomer), but have not had the age-ism issue. Maybe cuz I've
been in business for myself (and with partners) for that last 20+
years. I think that's the way to get around that problem especially
if you have a wide and varied base of talents and can answer the
technical questions or know where to look for the answer.

Me, I'm a master of none. And I'll never make it as an accountant !

That most of my friends and family don't see the appeal or understand
what it's all about doesn't bother me much it's not the kind of stuff
you can post about on Facebook and expect dozens of "likes" like a woman
in her underwear. Oh well.

 

[boB]

On Sat, 11 Apr 2020 12:29:26 -0700 (PDT), sea moss
<danluster81@gmail.com> wrote:

I guess the big question is, what are you wanting to do with the
controller ?
snip

boB

I am driving a thermoelectric cooler with an H-bridge configuration (inductor in series with the TEC). So I need to drive 4 switches, but really only need one PWM signal and its inverse.

Since there are only so many PWM controllers with 4 outputs (and 2 of them for driving high-side switches), I will likely need an external gate driver IC. Also, I need to be able to drive the reference pin with the temperature setpoint, and the majority of PWM controllers don't allow for external reference. This is what led me down the path of "you know what I'll just find the simplest possible PWM block and do the rest myself"

Also, yeah I have used the UCx84x family a bit too. I might end up using one of those at the end of the day.

This is for work, so it could end up in production for many years.

AHA !!! Great !

You'll certainly need a PWM controller. But you will also need dead
time control.

For full bridge, I am useing external FET drivers but depending on the
gate drive constraints and frequency and all that, that is secondary
to the PWM unless the dead time is included in the driver.

There are some 1/2 bridge drivers that take care of the dead time.

My latest full bridge PWM is being done with the advanced timers in an
STM32F4xx processor. That takes care of the dead time and PWM and
stuff from pins that just go o the FET drivers. In my case,
individual gate optically coupled drivers.

You could use that Microchip part of course and invert the output and
drive one of thse 1/2 bridge FET drivers using diode-cap charge pump
for the high side drive. 18V or something like that.

This is fun stuff ! But you have lots of choices.

BTW, I think we pay around 35 cents fo the UCC3843 parts so they are
definitely cheap, if that matters.

About the same price for the Greenpaks from Dialog or Silego... I use
those in another circuit to generate dead time for the 4 corner gate
drivers from 2 lines of PWM from a single peripheral to do phase
shift PWM. The dead time control into the Greenpak is controlled from
another PWM peripheral at a few MHz so it an be adjusted in software.
The Silego does a bit more than that but is an inexpensive part that
helps do a lot of stuff.

 

[bitrex]

On 4/12/2020 2:16 AM, bitrex wrote:

I'm 65 (a boomer), but have not had the age-ism issue.  Maybe cuz I've
been in business for myself (and with partners) for that last 20+
years.   I think that's the way to get around that problem especially
if you have a wide and varied base of talents and can answer the
technical questions or know where to look for the answer.

I went to art college I didn't really start taking STEM classes
(adult-ed) until my late 20s/early 30s when I was looking to get out of
the industry I was in. But like a lot of guys who are into electronics
as adults I guess I'd been writing BASIC and Pascal programs and
building little dioramas with working miniature streetlights for school
projects and such since I was a child.

My father was 52 when I was born (I'm the youngest of four) and a WWII
vet but had trouble finding well-paid work sometimes by that point also
because didn't have a college degree in addition to his age. He wasn't
particularly tech-literate then and never was but he decided our family
should get a computer as soon as the PC became relatively affordable -
"this computer-stuff is going to be really big, someday."

Also it would have been difficult for a 62 y/o to keep up with a 10 y/o
on the ball field but father-son time at the computer was a way for him
to stay engaged

 

[bitrex]

On 4/12/2020 1:10 AM, boB wrote:

On Sun, 12 Apr 2020 00:57:06 -0400, bitrex <user@example.net> wrote:

On 4/12/2020 12:42 AM, boB wrote:
On Sat, 11 Apr 2020 14:20:17 -0400, bitrex <user@example.net> wrote:

On 4/11/2020 2:11 PM, Winfield Hill wrote:
bitrex wrote...

... do that for another ~25 years before I have a
shot at retirement...

Is retirement a good thing?



I mean "retirement" in the sense of having enough money to still afford
food and a place to live when I can't work a full 70 hours a week in the
year 2050 and thereby avoid the wrath of whatever fashion of bipedal
jackal-headed Egyptian God-emperor, sentient gaseous nebula the size of
the Solar system, or "benevolent" quantum artificial intelligence that
rules Earth circa the year 2050.


I cannot see me "retiring" from electronics. Only freeing my time up
to do things I want to do. I don't think I will be around by 2050,
or at least be able to hold on to a soldering iron.

Maybe, if I am successful at "retirement", I can hire a couple of
technicians to help me build circuits that I have always wanted to
build ! Dream products !

boB



No, I don't expect I'll ever stop doing it, that aspect was unclear to
me when I started fiddling with transistors in my early 20s but in my
early 40s it's become clear I'll be doing this in some capacity as long
as I can. But I'm even now, not as young and energetic as I used to be
and how long I can do it for pay is a question.

Age-ism in the tech field is real (as it is in many fields) and even at
40 on the software-side at least I'm the "old man" and Granpa already.
Age-ism seems to be the last socially acceptable form of bigotry and you
can see it lots of places and I'm guilty of it from time to time myself,
ok, boomer?



I'm 65 (a boomer), but have not had the age-ism issue. Maybe cuz I've
been in business for myself (and with partners) for that last 20+
years. I think that's the way to get around that problem especially
if you have a wide and varied base of talents and can answer the
technical questions or know where to look for the answer.

I went to art college I didn't really start taking STEM classes
(adult-ed) until my late 20s/early 30s when I was looking to get out of
the industry I was in. But like a lot of guys who are into electronics
as adults I guess I'd been writing BASIC and Pascal programs and
building little dioramas with working miniature streetlights for school
projects and such since I was a child.

My father was 52 when I was born (I'm the youngest of four) and a WWII
vet but had trouble finding well-paid work sometimes by that point also
because didn't have a college degree in addition to his age. He wasn't
particularly tech-literate then and never was but he decided our family
should get a computer as soon as the PC became relatively affordable -
"this computer-stuff is going to be really big, someday."

> Me, I'm a master of none. And I'll never make it as an accountant !

I wanted to be a rock star when I was a teenager. I did work in the
music/recording/entertainment industry for a while after college. Long
enough to learn I NEVER WANT TO BE A ROCK STAR

That most of my friends and family don't see the appeal or understand
what it's all about doesn't bother me much it's not the kind of stuff
you can post about on Facebook and expect dozens of "likes" like a woman
in her underwear. Oh well.

 

[Klaus Kragelund]

On Sunday, April 12, 2020 at 12:41:22 AM UTC+2, Lasse Langwadt Christensen wrote:

lørdag den 11. april 2020 kl. 02.10.07 UTC+2 skrev bitrex:
On 4/10/2020 7:59 PM, Ricky C wrote:
On Friday, April 10, 2020 at 7:19:36 PM UTC-4, sea moss wrote:
Seems like every time I start a new power design, I waste a bunch of time looking for the ideal PWM controller.

At the end of the day I'd really like to have the simplest IC possible to handle just the PWM function, and I provide my own error amp, gate driver, and reference externally. The ideal part would look like this: oscillator set by resistor, comparator non-inverting input, and pulse out. Plus Vdd and ground equals 5 pins only! Does anything like this exist?

I've also been checking out the famous TL494, and MC34063 since I have never used them. Does anyone here have horror stories from these parts that I can't infer from the datasheets?

Another one I discovered is MCP1632, pretty simple but not quite what I'm looking for. Vdd=6V max for example, kind of sucks. I do like how they use a 50uA current source as the reference pin, so you set Vref with a resistor or drive from low-impedance source, nice.
http://ww1.microchip.com/downloads/en/DeviceDoc/20005254A.pdf

I can't get to a 5 pin device, but I bet I can do that in a 48 pin QFN using an FPGA. ICE5LP1K-SG48ITR50, under $3.00 qty 100.

There's not much in the control world that can't be done primarily digitally these days.


ATTiny13A, 1k program memory, two PWM channels, 10 bit ADC, 20MHz clock..
can do all sorts of stuff with that for 40 cent in 100s

https://www.st.com/en/motor-drivers/stspin32f0a.html

48MHz Cortex-M0, 3x opamp, comparator, 3*halfbridge gatedriver, buck converter

I once did a digital SMPS with what Lasse suggest here.

The error signal was fed into the ADC and DMA transferred the error voltage directly to the PWM timer (so not computation involved)

Around that was looped a peak current limit and soft start

In this can it only replaces the PWM part

You can do more by adding the loop, but then you get phase problems if you loop is not fast, wrt to the PWM frequency

Cheers

Klaus

 

[Bill Sloman]

On Sunday, April 12, 2020 at 5:29:31 AM UTC+10, sea moss wrote:

I guess the big question is, what are you wanting to do with the
controller ?
snip

I am driving a thermoelectric cooler with an H-bridge configuration (inductor in series with the TEC). So I need to drive 4 switches, but really only need one PWM signal and its inverse.

Since there are only so many PWM controllers with 4 outputs (and 2 of them for driving high-side switches), I will likely need an external gate driver IC. Also, I need to be able to drive the reference pin with the temperature setpoint, and the majority of PWM controllers don't allow for external reference. This is what led me down the path of "you know what I'll just find the simplest possible PWM block and do the rest myself"

Also, yeah I have used the UCx84x family a bit too. I might end up using one of those at the end of the day.

This is for work, so it could end up in production for many years.

Sloman A.W., Buggs P., Molloy J., and Stewart D. “A microcontroller-based driver to stabilise the temperature of an optical stage to 1mK in the range 4C to 38C, using a Peltier heat pump and a thermistor sensor” Measurement Science and Technology, 7 1653-64 (1996)

Describes an example of such a circuit. We got the the low frequency content of the PWM waveform down by playing around a small programmable logic device. The device is long obsolete, but there are plenty of more modern equivalents around.

--
Bill Sloman, Sydney