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PWM controllers... shopping

Started by sea moss April 10, 2020
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 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.
> 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.
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.
> > 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.
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
> 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.
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
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
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