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Boost Converter Tutorial?

Started by Jim Thompson February 11, 2012
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in 
message news:ckcdj752sf9bdk5cuf58c7bfdjvo1214f5@4ax.com...
> On Sat, 11 Feb 2012 13:25:00 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>Jim Thompson wrote: >>> >>> In the past I have designed boost converters in burst mode, with peak >>> current control, but never with a PWM-controlled loop. >>> >>> Outputs: +5 @ 25mA, -5V @ 20mA >>> >>> Can someone point me to a tutorial? >>> >>> Thanks! >>> >>> [Don't point me to an off-the-shelf part. This has to go into a >>> _custom_ chip... just a little thing... 1mm x 25mm :-] >> >>Hmm, an inch long and a millimeter wide--it's for a robotic cockroach, >>right? >> >>Cheers >> >>Phil Hobbs > > Nope. It goes in something that virtually every person owns :-)
That'll be a watch then....
TTman wrote:

> "Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in > message news:ckcdj752sf9bdk5cuf58c7bfdjvo1214f5@4ax.com... > >>On Sat, 11 Feb 2012 13:25:00 -0500, Phil Hobbs >><pcdhSpamMeSenseless@electrooptical.net> wrote: >> >> >>>Jim Thompson wrote: >>> >>>>In the past I have designed boost converters in burst mode, with peak >>>>current control, but never with a PWM-controlled loop. >>>> >>>>Outputs: +5 @ 25mA, -5V @ 20mA >>>> >>>>Can someone point me to a tutorial? >>>> >>>>Thanks! >>>> >>>>[Don't point me to an off-the-shelf part. This has to go into a >>>>_custom_ chip... just a little thing... 1mm x 25mm :-] >>> >>>Hmm, an inch long and a millimeter wide--it's for a robotic cockroach, >>>right? >>> >>>Cheers >>> >>>Phil Hobbs >> >>Nope. It goes in something that virtually every person owns :-) > > > That'll be a watch then.... > >
I was going to say a tooth brush but, I've been in parts where that maybe not be true :) Jamie
On Sat, 11 Feb 2012 19:44:16 -0000, "TTman" <pcw1.cad@ntlworld.com>
wrote:

> >"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in >message news:ckcdj752sf9bdk5cuf58c7bfdjvo1214f5@4ax.com... >> On Sat, 11 Feb 2012 13:25:00 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>>Jim Thompson wrote: >>>> >>>> In the past I have designed boost converters in burst mode, with peak >>>> current control, but never with a PWM-controlled loop. >>>> >>>> Outputs: +5 @ 25mA, -5V @ 20mA >>>> >>>> Can someone point me to a tutorial? >>>> >>>> Thanks! >>>> >>>> [Don't point me to an off-the-shelf part. This has to go into a >>>> _custom_ chip... just a little thing... 1mm x 25mm :-] >>> >>>Hmm, an inch long and a millimeter wide--it's for a robotic cockroach, >>>right? >>> >>>Cheers >>> >>>Phil Hobbs >> >> Nope. It goes in something that virtually every person owns :-) > >That'll be a watch then.... >
No. Think teenagers... what are they never seen without ?:-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Sat, 11 Feb 2012 11:22:38 -0700, Jim Thompson wrote:

> In the past I have designed boost converters in burst mode, with peak > current control, but never with a PWM-controlled loop. > > Outputs: +5 @ 25mA, -5V @ 20mA > > Can someone point me to a tutorial? > > Thanks! > > [Don't point me to an off-the-shelf part. This has to go into a > _custom_ chip... just a little thing... 1mm x 25mm :-]
Actually, I'd go looking at off-the-shelf parts to snag ideas from. Efficiency? Regulation bounds? % of total product cost that'll be taken up by the converter? Unless the above answers are "low, loose, and low", I think your biggest challenge won't be the silicon, it'll be finding small, economical & high performance inductors, designing the thing to take advantage of them, and dancing around the inevitable unstable zero in the boost converter. Are you planning on paying for the 0.3V drop of a Schottkey on each supply, or the time & trouble to drive the extra two switches & make it synchronous? -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
>> > > No. Think teenagers... what are they never seen without ?:-) >
Decent clothes ? lol U seen the ones in the UK where their pants crotch comes down to their knees .... PMSL Doh that dreaded thumb rattling Mobile :( Got any good designs for a blocker ????
"Tim Wescott" <tim@seemywebsite.please> wrote in message 
news:SLKdnamUgb08VavSnZ2dnUVZ_t2dnZ2d@web-ster.com...
> On Sat, 11 Feb 2012 11:22:38 -0700, Jim Thompson wrote: > >> In the past I have designed boost converters in burst mode, with peak >> current control, but never with a PWM-controlled loop. >> >> Outputs: +5 @ 25mA, -5V @ 20mA >> >> Can someone point me to a tutorial? >> >> Thanks! >> >> [Don't point me to an off-the-shelf part. This has to go into a >> _custom_ chip... just a little thing... 1mm x 25mm :-] > > Actually, I'd go looking at off-the-shelf parts to snag ideas from. > > Efficiency? Regulation bounds? % of total product cost that'll be taken > up by the converter? > > Unless the above answers are "low, loose, and low", I think your biggest > challenge won't be the silicon, it'll be finding small, economical & high > performance inductors, designing the thing to take advantage of them, and > dancing around the inevitable unstable zero in the boost converter. > > Are you planning on paying for the 0.3V drop of a Schottkey on each > supply, or the time & trouble to drive the extra two switches & make it > synchronous? > > -- > Tim Wescott > Control system and signal processing consulting > www.wescottdesign.com
He's a real tease.. probably got all that sorted already....
On Sat, 11 Feb 2012 20:03:22 +0000, TTman wrote:

> "Tim Wescott" <tim@seemywebsite.please> wrote in message > news:SLKdnamUgb08VavSnZ2dnUVZ_t2dnZ2d@web-ster.com... >> On Sat, 11 Feb 2012 11:22:38 -0700, Jim Thompson wrote: >> >>> In the past I have designed boost converters in burst mode, with peak >>> current control, but never with a PWM-controlled loop. >>> >>> Outputs: +5 @ 25mA, -5V @ 20mA >>> >>> Can someone point me to a tutorial? >>> >>> Thanks! >>> >>> [Don't point me to an off-the-shelf part. This has to go into a >>> _custom_ chip... just a little thing... 1mm x 25mm :-] >> >> Actually, I'd go looking at off-the-shelf parts to snag ideas from. >> >> Efficiency? Regulation bounds? % of total product cost that'll be >> taken up by the converter? >> >> Unless the above answers are "low, loose, and low", I think your >> biggest challenge won't be the silicon, it'll be finding small, >> economical & high performance inductors, designing the thing to take >> advantage of them, and dancing around the inevitable unstable zero in >> the boost converter. >> >> Are you planning on paying for the 0.3V drop of a Schottkey on each >> supply, or the time & trouble to drive the extra two switches & make it >> synchronous? >> >> -- >> Tim Wescott >> Control system and signal processing consulting www.wescottdesign.com > > He's a real tease.. probably got all that sorted already....
Well, I would hope so. But you could do everything he's asking for with a couple of charge pumps followed by linear regulators, if you didn't mind the inefficiency. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On Sat, 11 Feb 2012 20:00:36 -0000, "TTman" <pcw1.cad@ntlworld.com>
wrote:

>>> >> >> No. Think teenagers... what are they never seen without ?:-) >> > >Decent clothes ? lol >U seen the ones in the UK where their pants crotch comes down to their knees >.... PMSL > >Doh that dreaded thumb rattling Mobile :( >Got any good designs for a blocker ???? >
No blocker. But I understand that new movie theater installs in the US are shielded sufficiently that cell phones don't function in the auditorium portion of the facility. I know that at least one theater I frequent requests that doctors leave their cell phones and pagers at the front desk if they're "on-call"... an usher will come and notify them as needed. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Sat, 11 Feb 2012 13:59:29 -0600, Tim Wescott
<tim@seemywebsite.please> wrote:

>On Sat, 11 Feb 2012 11:22:38 -0700, Jim Thompson wrote: > >> In the past I have designed boost converters in burst mode, with peak >> current control, but never with a PWM-controlled loop. >> >> Outputs: +5 @ 25mA, -5V @ 20mA >> >> Can someone point me to a tutorial? >> >> Thanks! >> >> [Don't point me to an off-the-shelf part. This has to go into a >> _custom_ chip... just a little thing... 1mm x 25mm :-] > >Actually, I'd go looking at off-the-shelf parts to snag ideas from. > >Efficiency?
As high as practical.
>Regulation bounds?
Loose. Lots of compensating innards for power supply variation.
> % of total product cost that'll be taken >up by the converter?
They've already committed to external switch(es)
> >Unless the above answers are "low, loose, and low", I think your biggest >challenge won't be the silicon, it'll be finding small, economical & high >performance inductors, designing the thing to take advantage of them, and >dancing around the inevitable unstable zero in the boost converter.
The inductor _is_ a problem. They're already at their height limit and their present implementation (at lower current) is just pushing into saturation :-(
> >Are you planning on paying for the 0.3V drop of a Schottkey on each >supply, or the time & trouble to drive the extra two switches & make it >synchronous?
That's up for debate. But this client is no onesy-twosy outfit... they just shipped their BILLIONETH chip! ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Sat, 11 Feb 2012 14:11:01 -0600, Tim Wescott
<tim@seemywebsite.please> wrote:

>On Sat, 11 Feb 2012 20:03:22 +0000, TTman wrote: > >> "Tim Wescott" <tim@seemywebsite.please> wrote in message >> news:SLKdnamUgb08VavSnZ2dnUVZ_t2dnZ2d@web-ster.com... >>> On Sat, 11 Feb 2012 11:22:38 -0700, Jim Thompson wrote: >>> >>>> In the past I have designed boost converters in burst mode, with peak >>>> current control, but never with a PWM-controlled loop. >>>> >>>> Outputs: +5 @ 25mA, -5V @ 20mA >>>> >>>> Can someone point me to a tutorial? >>>> >>>> Thanks! >>>> >>>> [Don't point me to an off-the-shelf part. This has to go into a >>>> _custom_ chip... just a little thing... 1mm x 25mm :-] >>> >>> Actually, I'd go looking at off-the-shelf parts to snag ideas from. >>> >>> Efficiency? Regulation bounds? % of total product cost that'll be >>> taken up by the converter? >>> >>> Unless the above answers are "low, loose, and low", I think your >>> biggest challenge won't be the silicon, it'll be finding small, >>> economical & high performance inductors, designing the thing to take >>> advantage of them, and dancing around the inevitable unstable zero in >>> the boost converter. >>> >>> Are you planning on paying for the 0.3V drop of a Schottkey on each >>> supply, or the time & trouble to drive the extra two switches & make it >>> synchronous? >>> >>> -- >>> Tim Wescott >>> Control system and signal processing consulting www.wescottdesign.com >> >> He's a real tease.. probably got all that sorted already.... > >Well, I would hope so. But you could do everything he's asking for with >a couple of charge pumps followed by linear regulators, if you didn't >mind the inefficiency.
Try 32 Ohm "bumps" and you see another aspect of the problem :-( ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.