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PWM controllers... shopping

Started by sea moss April 10, 2020
On Fri, 10 Apr 2020 16:19:31 -0700 (PDT), sea moss
<danluster81@gmail.com> 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 > >
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 Science teaches us to doubt. Claude Bernard
On 4/10/2020 8:27 PM, sea moss wrote:
> >> You can design your own if you want using something like the >> Silego/Dialog GreenPAK OTP mixed-signal PLC: >> >> <https://www.dialog-semiconductor.com/configurable-mixed-signal> > > I have used Greenpaks, I really like them. Great for glue logic. Not sure if their analog blocks are up to this task, though. I'll have a browse at their current devices, it's been a few years. >
I have a client whose final design is going to be about the size of a postage stamp thanks to those, he was sighing and saying "well I guess if we can get it to perhaps 3" by 3" with today's tech that's just what I'll have to work with"...Heh
On 4/10/2020 8:24 PM, sea moss wrote:
>> 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 > > Yeah but it seems like overkill to have C code that just performs a comparator function... plus I wonder how much jitter you would get from using that 10 bit ADC >
IDK if the ATTiny13 has it but a number of devices from that line have hardware dead-time generators on the PWM outputs so the manufacturer clearly expected it could be used in a switch-controller role
On 4/10/2020 8:24 PM, sea moss wrote:
>> 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 > > Yeah but it seems like overkill to have C code that just performs a comparator function... plus I wonder how much jitter you would get from using that 10 bit ADC >
the line has some other occasionally useful features in certain applications like the ones with differential ADCs can sense high-side up to several volts over the uP's own supply rail without additional hardware
Why do you need an external error amp, or all the other things?  Internal 
ones are so nice.

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

TL494 is fine, but it's a big chip for most purposes, and isn't current mode 
as such.  Very hungry, something like ~10mA operating.  It can be used for 
average current mode pretty easily (use one err amp for low side current 
sense feedback, disable the other), but you do need to add an external 
voltage error amp.  (In an isolated circuit, this is the secondary side 
TL431 or whatever, which works out nicely.)

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

At least the NCP3064 has proper cutoff under current limiting conditions; I 
don't feel bad using it, but I would still prefer something with lower 
output ripple.

TPS54xxx and others are good for local supplies.  Hundreds to select from; 
picking any single one would be futile.  Parametric search on ti.com, 
Digi-Key and others is the way to go.

Tim

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

"sea moss" <danluster81@gmail.com> wrote in message 
news:4fb6d1db-b955-40ab-b8f7-5156a39f6e3d@googlegroups.com...
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



On Fri, 10 Apr 2020 16:19:31 -0700 (PDT), sea moss
<danluster81@gmail.com> 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 guess the big question is, what are you wanting to do with the controller ? Sometimes a micro is good enough. Sometimes one of thsoe Greenpaks are good. I use them. I also use the UC3843 family of current mode controllers. They are similar to the Microchip device you linked to but are slightly different. Depends on the application. And is it for a product where you would buy a lot of them ? Or a one off project ? boB
On 11/04/2020 08:46, boB wrote:
> On Fri, 10 Apr 2020 16:19:31 -0700 (PDT), sea moss > <danluster81@gmail.com> 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 guess the big question is, what are you wanting to do with the > controller ?
There have been a dozen answers to the OP already, all promoting the predictable favourite solutions. For any question in electronics, Rick will inevitably claim an FPGA is the simplest, cheapest and most flexible solution. John Larkin will want to do it all in analogue electronics. Bitrex will immediately propose a small microcontroller. Then they will argue about the pros and cons of these. Thank you for that breath of fresh air, asking what the thing is supposed to do. Only once that is figured out, is it possible to look at ideas for a solution.
> > Sometimes a micro is good enough. Sometimes one of thsoe Greenpaks > are good. I use them. > > I also use the UC3843 family of current mode controllers. They are > similar to the Microchip device you linked to but are slightly > different. > > Depends on the application. And is it for a product where you would > buy a lot of them ? Or a one off project ? > > boB >
On 4/11/2020 9:52 AM, David Brown wrote:
> On 11/04/2020 08:46, boB wrote: >> On Fri, 10 Apr 2020 16:19:31 -0700 (PDT), sea moss >> <danluster81@gmail.com> 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.&nbsp; The ideal part would >>> look like this: oscillator set by resistor, comparator non-inverting >>> input, and pulse out.&nbsp; Plus Vdd and ground equals 5 pins only!&nbsp; Does >>> anything like this exist? >>> >>> I've also been checking out the famous TL494, and MC34063 since I >>> have never used them.&nbsp; 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.&nbsp; Vdd=6V max for example, kind of sucks.&nbsp; 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 guess the big question is, what are you wanting to do with the >> controller ? > > There have been a dozen answers to the OP already, all promoting the > predictable favourite solutions.&nbsp; For any question in electronics, Rick > will inevitably claim an FPGA is the simplest, cheapest and most > flexible solution.&nbsp; John Larkin will want to do it all in analogue > electronics.&nbsp; Bitrex will immediately propose a small microcontroller. > Then they will argue about the pros and cons of these.
These are....scurrilous accusations!!
> Thank you for that breath of fresh air, asking what the thing is > supposed to do.&nbsp; Only once that is figured out, is it possible to look > at ideas for a solution.
That's the ideal, sure, but often "what do you want to do" is the hardest question to get a straight answer on, and by the time you get one and start pondering potential solutions it starts to feel like work one should be getting paid for. I dunno about other people but I still optimistically have to do that for another ~25 years before I have a shot at retirement...
>> >> Sometimes a micro is good enough.&nbsp; Sometimes one of thsoe Greenpaks >> are good.&nbsp; I use them. >> >> I also use the UC3843 family of current mode controllers.&nbsp; They are >> similar to the Microchip device you linked to but are slightly >> different. >> >> Depends on the application.&nbsp; And is it for a product where you would >> buy a lot of them ?&nbsp; Or a one off project ? >> >> boB >> >
bitrex wrote...
> > ... do that for another ~25 years before I have a > shot at retirement...
Is retirement a good thing? -- Thanks, - Win
l&oslash;rdag 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