## Is A SEPIC Convertor Really All That Efficient ?

Started by in sci.electronics.design3 years ago 12 replies

It came up recently, friend of mine has an application where it would be good. I told him it would take me a LONG time to design one from scratch....

It came up recently, friend of mine has an application where it would be good. I told him it would take me a LONG time to design one from scratch. But anyway I thought of something. Many years ago in the TV days I was working on a plasma and it had a SEPIC running one of the screen voltage. They do pull current like a CRT. Thing is, it had a well regulated SMPS. Tye SEPICs are

## SMPS +/-5V about +50V supply.

Started by in sci.electronics.design3 years ago 7 replies

I want a switch mode PSU which will give me two ~2A outputs at 5V above and below a nominal +50V (say +40V to +60V) DC supply, ie +55V and +45V...

I want a switch mode PSU which will give me two ~2A outputs at 5V above and below a nominal +50V (say +40V to +60V) DC supply, ie +55V and +45V from +50V. I can probably work out some fairly clunky ways of doing this, but it seems possible that there's some topology particularly suited to this type of thing. Any thoughts? Cheers -- Clive

## SMPS -- How to drive the H bridge?

Started by in sci.electronics.design10 years ago 11 replies

I have a somewhat basic question on driving a H bridge: Assume the 4 switches making up the bridge are Q(L,T), Q(R,T), Q(L,B), Q(R,B), where...

I have a somewhat basic question on driving a H bridge: Assume the 4 switches making up the bridge are Q(L,T), Q(R,T), Q(L,B), Q(R,B), where R= right, L=left, T=top, B=bottom. Typically, Q(L,T) & Q(R,B) are ON in the even cycles (say) while Q(R,T), Q(L,B) are OFF. In the odd cycles Q(R,T) & Q(L,B) are ON while Q(L,T) & Q(R,B) are held OFF. The drive is a square wave with some duty cycle. D...

## More CUI SMPS

Started by in sci.electronics.design6 years ago 6 replies

Well when it rains it pours. I've got another couple of circuits where I need to replace an old linear supply that is not longer available....

Well when it rains it pours. I've got another couple of circuits where I need to replace an old linear supply that is not longer available. So I'm again trying the wall wart and a CUI three terminal regulator on the pcb. One of these, V7815 http://www.cui.com/product/resource/v78-500.pdf After much mucking about I found that the remaining pickup was broadcast.. over the air. (I ...

## SMPS Topologies

Started by in sci.electronics.design5 years ago 62 replies

Gentlemen, What's the exact technical term for the switcher topology where you only have one large toroidal (typically) transformer right at...

Gentlemen, What's the exact technical term for the switcher topology where you only have one large toroidal (typically) transformer right at the mains entry point which takes line AC and outputs it at a lower voltage level whereupon it's fed into the bridge rectifier and thence into a large storage cap whereupon it can be chopped up, regulated and finally filtered, there being no othe...

## Syncronizing SMPS and EMC Noise

Started by in sci.electronics.design8 years ago 10 replies

Hi Anyone got experience with the difference between synchronized and un-synchronized converters? Say they have the same noise level,...

Hi Anyone got experience with the difference between synchronized and un-synchronized converters? Say they have the same noise level, wouldn't the quasi peak noise in an un-synchronized system be 6dB higher than the synchronized one? (Due to beating between the 2 noise sources) Cheers Klaus

## My first switcher

Started by in sci.electronics.design6 years ago 28 replies

Hi all, Well I get to do a SMPS. There are boat loads of IC's out there and I'm looking for recommendations. (I better go re read AoE3) I...

Hi all, Well I get to do a SMPS. There are boat loads of IC's out there and I'm looking for recommendations. (I better go re read AoE3) I need a number of output voltages. +15V, +5V, -5V, -15V. and +24V. maximum current of 0.5A on any one. My current plan is to run the whole thing from a 24V wall wart or brick. Price and size is not too much of an issue, I guess fewer external pa...

## Toroidal Transformer Screening

Started by in sci.electronics.design7 years ago 11 replies

Hi Another magnetics question! I have a SMPS which uses a toroidal ferrite transformer. It switches at ~100kHz, works very well, it's not...

Hi Another magnetics question! I have a SMPS which uses a toroidal ferrite transformer. It switches at ~100kHz, works very well, it's not my design and I can't change it. However, it introduces noise at about 50kHz onto/into my electronics which causes a problem. After much experimentation, I found that putting an earthed screen around the transformer kills the problem quite dra...

## Dumb question regarding SMPS

Started by in sci.electronics.design10 years ago 99 replies

If someone has a free moment, I'd like to know: I'm on my third laptop right now. Every time I plugged my Dell's "fat snake" into the wall, I...

If someone has a free moment, I'd like to know: I'm on my third laptop right now. Every time I plugged my Dell's "fat snake" into the wall, I drew quite an arc. The Lenovo's arc was not noticeable, but now I get a noticeable arc with my new HP -- not as big as the Dell's, however. I know FA about switch mode power supplies, obviously, so I wonder 1. What produces the arc? 2. Why would...

## Homework (SMPS)

Started by in sci.electronics.design9 years ago 6 replies

Hi guys, So I signed up for this power electronics course that Klaus linked= to a week or so ago. (from coursera and CU). =20 I wanted to...

Hi guys, So I signed up for this power electronics course that Klaus linked= to a week or so ago. (from coursera and CU). =20 I wanted to check my homework so I made an LTspice file. =20 (I=92ve changed it a bit so as not to give HW answer.) =20 I=92ve got a question. If you look at the simulation there is this rather l= arge turn on transient. =20 Transient has a period of ~1.3 mS (~77...

## Inductor saturation during smps startup

Started by in sci.electronics.design6 years ago 21 replies

I was looking at using an LT1170 in a Positive-to-Negative Buck-Boost Converter, as per page 14 of this data...

I was looking at using an LT1170 in a Positive-to-Negative Buck-Boost Converter, as per page 14 of this data sheet http://docs-asia.electrocomponents.com/webdocs/13ec/0900766b813ec9fd.pdf Thing is, when I put this into LTSpice (using Linear Techology's own model of their part), it shows that the current through the inductor rises to 10 amps, during start-up, settling to something more ...

## Reducing SMPS noise

Started by in sci.electronics.design6 years ago 43 replies

I'm working on a PCB that contains nearly 30 resistors in a ladder configuration, each step switched in or out by a SMT solid state relay. It's...

I'm working on a PCB that contains nearly 30 resistors in a ladder configuration, each step switched in or out by a SMT solid state relay. It's essentially a decade box for a specific application. The relays are controlled by a micro and all is powered by a boardmount enclosed CUI AC/DC switching converter, supplying up to 400mA. The resistors are electrically isolated from the SM

## What does a "self-ballasted" LED mean ?

Started by in sci.electronics.design8 years ago 7 replies

Could some electronics guru pleas explain what a "self-ballasted" LED lamp mean ? I have seen LED lamps, running off the AC line, and...

Could some electronics guru pleas explain what a "self-ballasted" LED lamp mean ? I have seen LED lamps, running off the AC line, and powered by a simple small 5V 1 Amp SMPS, but what exactly does a self-ballasted LED lamp mean ?

## Groundplane under SMPS power inductor

Started by in sci.electronics.design7 years ago 48 replies

I have seen designs where there is a cutout in the groundplane under the power inductor in e.g. a buck converter. Inductor is nominally...

I have seen designs where there is a cutout in the groundplane under the power inductor in e.g. a buck converter. Inductor is nominally a "shielded" one. I assume it is to prevent some kind of "shorted turn" effect? What do you think? Might a continuous plane be better? It could help to shield any field leakage and reduce emissions and circuit noise. I am asking generally, but say 1...

## Brown material used in hybrids

Started by in sci.electronics.design7 years ago 16 replies

Hi, in this NASA workshop handout on hermeticity testing there are a number of photos of semiconductors and some SMPS-looking hybrids....

Hi, in this NASA workshop handout on hermeticity testing there are a number of photos of semiconductors and some SMPS-looking hybrids. I'm wondering what the material is that they've used to tack down fly wires and such like. Is it a special epoxy or some kind of flexible silicone or something else entirely? http://nepp.nasa.gov/workshops/etw2013/talks/Tue_June11_2013/1630_McManus_Pressne...

## Voltage to PWM

Started by in sci.electronics.design6 years ago 18 replies

Hi all, I want to make a V to PWM circuit. (For a servoed heater.) I drew a triangle wave into a comparator, and that seems simple enough. ...

Hi all, I want to make a V to PWM circuit. (For a servoed heater.) I drew a triangle wave into a comparator, and that seems simple enough. Though it will take a few IC for the triangle wave. (I guess I could use an opamp and dual comparator.) So I went searching for V-PWM IC's. Most are for SMPS controll, which seem overly complicated for what I want. I also want a fairly low...

## SMPS LC filter... not!?

Started by in sci.electronics.design6 years ago 4 replies

Hi all, I'm having a big fail when trying to make an LC filter for a CUI SPMS. There's nothing to the circuit. ...

Hi all, I'm having a big fail when trying to make an LC filter for a CUI SPMS. There's nothing to the circuit. Here. https://www.dropbox.com/s/xgesfnb3a6z0x1n/L-C-schem.JPG?dl=0 The problem is that no matter what I do to the Land or C's the output always has the same amount, (shape and size) of ripple. Here's a 'scope shot. https://www.dropbox.com/s/inv0w000gdm9le7/TEK0042.BMP?dl=...

## Inductor Voltage Rating?

Started by in sci.electronics.design9 years ago 32 replies

I have to make low power SMPS operable up to several hundred volts. For obvious reasons, it would be good to use off the shelf SMT...

I have to make low power SMPS operable up to several hundred volts. For obvious reasons, it would be good to use off the shelf SMT inductors. In datasheets, they always specify inductor max. current, however they don't say anything about max. voltage. Any advice or relevant experience? Vladimir Vassilevsky DSP and Mixed Signal Designs www.abvolt.com

## Late 1970s SMPS Design Query

Started by in sci.electronics.design6 years ago 182 replies

Gentlemen, May I draw your attention to this schematic for what I believe is termed a "resonant converter" (the power supply section from...

Gentlemen, May I draw your attention to this schematic for what I believe is termed a "resonant converter" (the power supply section from an old boat anchor oscilloscope) - https://www.flickr.com/photos/128859641@N02/24535280896/in/dateposted- public/ Can some kind soul explain the workings of the dozen or so components labelled "Function: resonance circuit"? I'm completely unfam...

## 8086 powered IBM PC compatible

Started by in sci.electronics.design11 years ago 95 replies

Could someone design for me a 8086 powered computer which is IBM compatible requirement: 1. using toroidal transformer as power supply...

Could someone design for me a 8086 powered computer which is IBM compatible requirement: 1. using toroidal transformer as power supply instead of SMPS 2. using SRAM instead of DRAM 3. using super I/O chip this is to replace aging 8088 system, and also used to teach pure 16 bit design. thank you