Forums

Voltage to PWM chip (similar to class D)?

Started by Joerg May 29, 2014
Folks,

Does anyone know an IC that can turn a control voltage into PWM and can
handle PWM frequencies in the 50-1000kHz range? Similar to a class D
driver but has to go down to DC. The changes in control would be
restricted to the audio spectrum below 15kHz.

The LTC6992 does this nicely but isn't precise enough. Same with
555-style timers or switcher chips. I am looking for better 1% and
ideally a lot better, including nonlinearity, drift, warts and all. A uC
is not suitable either because it should be simple and I need very fine
control granularity, down to around 0.1%.

Can't use short-lived consumer chips for radios and TV sets and such.

-- 
Regards, Joerg

http://www.analogconsultants.com/
On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Folks, > >Does anyone know an IC that can turn a control voltage into PWM and can >handle PWM frequencies in the 50-1000kHz range? Similar to a class D >driver but has to go down to DC. The changes in control would be >restricted to the audio spectrum below 15kHz. > >The LTC6992 does this nicely but isn't precise enough. Same with >555-style timers or switcher chips. I am looking for better 1% and >ideally a lot better, including nonlinearity, drift, warts and all. A uC >is not suitable either because it should be simple and I need very fine >control granularity, down to around 0.1%. > >Can't use short-lived consumer chips for radios and TV sets and such.
I can design you a chip >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | 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.
Den torsdag den 29. maj 2014 23.20.26 UTC+2 skrev Joerg:
> Folks, > > > > Does anyone know an IC that can turn a control voltage into PWM and can > > handle PWM frequencies in the 50-1000kHz range? Similar to a class D > > driver but has to go down to DC. The changes in control would be > > restricted to the audio spectrum below 15kHz. > > > > The LTC6992 does this nicely but isn't precise enough. Same with > > 555-style timers or switcher chips. I am looking for better 1% and > > ideally a lot better, including nonlinearity, drift, warts and all. A uC > > is not suitable either because it should be simple and I need very fine > > control granularity, down to around 0.1%. > > > > Can't use short-lived consumer chips for radios and TV sets and such. >
does it have to be pwm? not hysteretic, deltasigma or UcD ? http://www.hypex.nl/technology/ucd.html -Lasse
>"PWM frequencies in the 50-1000kHz range?..."
Is it fifty or a thousand ? It makes a difference.
On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Folks, > >Does anyone know an IC that can turn a control voltage into PWM and can >handle PWM frequencies in the 50-1000kHz range? Similar to a class D >driver but has to go down to DC. The changes in control would be >restricted to the audio spectrum below 15kHz. > >The LTC6992 does this nicely but isn't precise enough. Same with >555-style timers or switcher chips. I am looking for better 1% and >ideally a lot better, including nonlinearity, drift, warts and all. A uC >is not suitable either because it should be simple and I need very fine >control granularity, down to around 0.1%. > >Can't use short-lived consumer chips for radios and TV sets and such.
How about a sawtooth or triangle waveform and a comparator. Close a feedback loop around that, with a PWM to DC converter; the PWM-DC part can be made very linear. -- John Larkin Highland Technology, Inc jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Den torsdag den 29. maj 2014 23.53.48 UTC+2 skrev John Larkin:
> On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid> > > wrote: > > > > >Folks, > > > > > >Does anyone know an IC that can turn a control voltage into PWM and can > > >handle PWM frequencies in the 50-1000kHz range? Similar to a class D > > >driver but has to go down to DC. The changes in control would be > > >restricted to the audio spectrum below 15kHz. > > > > > >The LTC6992 does this nicely but isn't precise enough. Same with > > >555-style timers or switcher chips. I am looking for better 1% and > > >ideally a lot better, including nonlinearity, drift, warts and all. A uC > > >is not suitable either because it should be simple and I need very fine > > >control granularity, down to around 0.1%. > > > > > >Can't use short-lived consumer chips for radios and TV sets and such. > > > > How about a sawtooth or triangle waveform and a comparator. Close a > > feedback loop around that, with a PWM to DC converter; the PWM-DC part > > can be made very linear. >
put loop around integrator,comparator and flipflop and you have deltasigma cut down to the bone, Version 4 SHEET 1 880 680 WIRE 496 -64 64 -64 WIRE -32 112 -96 112 WIRE 64 112 64 16 WIRE 64 112 48 112 WIRE 80 112 64 112 WIRE 192 112 80 112 WIRE -96 128 -96 112 WIRE 192 128 192 112 WIRE 272 128 192 128 WIRE 80 144 80 112 WIRE 272 176 208 176 WIRE 496 176 496 -64 WIRE 496 176 448 176 WIRE 608 176 576 176 WIRE 80 240 80 208 WIRE 208 256 208 176 WIRE -96 384 -96 208 WIRE 208 400 208 336 FLAG -96 384 0 FLAG 272 224 0 FLAG 208 400 0 FLAG 608 240 0 FLAG 80 240 0 SYMBOL voltage -96 112 R0 WINDOW 3 -226 54 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value SINE(.5 .4 1000) SYMBOL Digital\\dflop 352 80 R0 SYMATTR InstName A1 SYMBOL res 64 96 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL res 48 -80 R0 SYMATTR InstName R2 SYMATTR Value 10k SYMBOL cap 96 208 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C1 SYMATTR Value 10n SYMBOL voltage 208 240 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value PULSE(0 1 0 1n 1n 500n 1000n) SYMBOL res 592 160 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 1k SYMBOL cap 624 240 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C2 SYMATTR Value 10n TEXT -130 488 Left 2 !.tran 100m
On 5/29/2014 5:20 PM, Joerg wrote:
> Folks, > > Does anyone know an IC that can turn a control voltage into PWM and can > handle PWM frequencies in the 50-1000kHz range? Similar to a class D > driver but has to go down to DC. The changes in control would be > restricted to the audio spectrum below 15kHz. > > The LTC6992 does this nicely but isn't precise enough. Same with > 555-style timers or switcher chips. I am looking for better 1% and > ideally a lot better, including nonlinearity, drift, warts and all. A uC > is not suitable either because it should be simple and I need very fine > control granularity, down to around 0.1%. > > Can't use short-lived consumer chips for radios and TV sets and such. >
How about a CMOS 555 with a current source to charge the capacitor? Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Lasse Langwadt Christensen wrote:
> Den torsdag den 29. maj 2014 23.20.26 UTC+2 skrev Joerg: >> Folks, >> >> >> >> Does anyone know an IC that can turn a control voltage into PWM and can >> >> handle PWM frequencies in the 50-1000kHz range? Similar to a class D >> >> driver but has to go down to DC. The changes in control would be >> >> restricted to the audio spectrum below 15kHz. >> >> >> >> The LTC6992 does this nicely but isn't precise enough. Same with >> >> 555-style timers or switcher chips. I am looking for better 1% and >> >> ideally a lot better, including nonlinearity, drift, warts and all. A uC >> >> is not suitable either because it should be simple and I need very fine >> >> control granularity, down to around 0.1%. >> >> >> >> Can't use short-lived consumer chips for radios and TV sets and such. >> > > does it have to be pwm? > > not hysteretic, deltasigma or UcD ? > > http://www.hypex.nl/technology/ucd.html >
This one has to be PWM but we can possible delinearize upfront (possibly ...). Better would be a clean 1:1 PWM. -- Regards, Joerg http://www.analogconsultants.com/
jurb6006@gmail.com wrote:
>> "PWM frequencies in the 50-1000kHz range?..." > > Is it fifty or a thousand ? It makes a difference. >
Sorry, 50kHz to 1000kHz. -- Regards, Joerg http://www.analogconsultants.com/
John Larkin wrote:
> On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Folks, >> >> Does anyone know an IC that can turn a control voltage into PWM and can >> handle PWM frequencies in the 50-1000kHz range? Similar to a class D >> driver but has to go down to DC. The changes in control would be >> restricted to the audio spectrum below 15kHz. >> >> The LTC6992 does this nicely but isn't precise enough. Same with >> 555-style timers or switcher chips. I am looking for better 1% and >> ideally a lot better, including nonlinearity, drift, warts and all. A uC >> is not suitable either because it should be simple and I need very fine >> control granularity, down to around 0.1%. >> >> Can't use short-lived consumer chips for radios and TV sets and such. > > How about a sawtooth or triangle waveform and a comparator. Close a > feedback loop around that, with a PWM to DC converter; the PWM-DC part > can be made very linear. >
That's what I wanted to avoid for real estate reasons. But if I hafta I'll do it. -- Regards, Joerg http://www.analogconsultants.com/