need to build a 16.1V stablized buckboost - Electronic Circuits Projects Diagrams Free

terramir · 7th June 2004, 06:47 AM

I need to build a 16.1V buck boost That can handle a Voltage input anywhere from 18.5 to 9 V and current anywhere from 100 mA to 7A
is this possible to make with high efficency?
Let me know if you have a circuit
terramir

terramir · 9th June 2004, 09:00 AM

:cry: please does someone know of a buckboost circuit that could help me here?
I really need some help
terramir

Sebi · 9th June 2004, 02:25 PM

I mean, better to do this in two steps: build a boost converter with 36V output, and another buck 36V to 16.1V (L4970A from STmicro)

Oznog · 9th June 2004, 06:12 PM

Sure you can!
There's the Cuk converter, which unfortunately creates only negative voltages, so you'd probably cascade the buck/boost converters together.

Efficiency is limited. You can use a MOSFET in place of the flyback diode (if your chip supports it) and save part of the voltage drop losses there. But copper & core losses in the inductors leave you in the range of 80%-90%. Losses are lowest when when your ratio is 1:1 and gets higher from there. Unfortunately, getting losses down requires a lot of very specific knowledge of inductors and detailed specifications on the inductor core you've got, so count on the low end, maybe 70%.

I had did this with the PIC, by the way.

7 amps will require some pretty sizable inductors.

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7th June 2004, 06:47 AM	(permalink)
terramir	need to build a 16.1V stablized buckboost I need to build a 16.1V buck boost That can handle a Voltage input anywhere from 18.5 to 9 V and current anywhere from 100 mA to 7A is this possible to make with high efficency? Let me know if you have a circuit terramir

9th June 2004, 09:00 AM	(permalink)
terramir	:cry: please does someone know of a buckboost circuit that could help me here? I really need some help terramir

9th June 2004, 02:25 PM	(permalink)
Sebi	I mean, better to do this in two steps: build a boost converter with 36V output, and another buck 36V to 16.1V (L4970A from STmicro)

9th June 2004, 06:12 PM	(permalink)
Oznog	Sure you can! There's the Cuk converter, which unfortunately creates only negative voltages, so you'd probably cascade the buck/boost converters together. Efficiency is limited. You can use a MOSFET in place of the flyback diode (if your chip supports it) and save part of the voltage drop losses there. But copper & core losses in the inductors leave you in the range of 80%-90%. Losses are lowest when when your ratio is 1:1 and gets higher from there. Unfortunately, getting losses down requires a lot of very specific knowledge of inductors and detailed specifications on the inductor core you've got, so count on the low end, maybe 70%. I had did this with the PIC, by the way. 7 amps will require some pretty sizable inductors.