MCP16301 Iout 600 mA?

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Hello Freaks...

 

Doesn't anyone had used the MCP16301 on Iout around 600 mA? Does it goes up to 600 mA or I need the Boost Bias?

 

The maximum output current that I could do was 370mA, after that, increasing the load the output goes below 5V. I'm using the datasheet's circuit but using a higher inductor value, 100 uH.

I'm working on a protoboard, I didn't go to PCB yet.

I'll send a picture showing the waveform when the load is higher than 370 mA.

 

Blue trace = SW pin

Red trace = Vout

 

Blue - Inductor Input. Red Voutput

 

 

 

Regards,

Bruno Muswieck

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What does the documentation tell you?

 

http://www.microchip.com/wwwprod...

 

Have you tried the MCP16301 Design Analyzer v1.0 ?

 

As it's a Microchip product, wouldn't it be more appropriate to be asking in the Microchip forum?

 

I'm working on a protoboard

What kind of "protoboard", exactly? 

 

Note that layout can be extremely important - if not critical - for switch-mode designs...

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Last Edited: Mon. Jun 22, 2015 - 07:04 PM
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What does the documentation tell you?

That's everything ok.

 

 Have you tried the MCP16301 Design Analyzer v1.0 ?

 The Inductor DCR and Capacitor ESR I don't know. Can be the reason? frown

 

As it's a Microchip product, wouldn't it be more appropriate to be asking in the Microchip forum?

Good question. Since last Friday I'm waiting for the email to activate my account :(  Over here We exchange all the general electronics stuffs, then I posted over here...  

Regards,

Bruno Muswieck

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The inductor must be 22uH. 100uH will not store enough energy to do what you would like. Also be aware of the Isat of the inductor you choose. Important. Also use ceramic caps. Let us know how it works out for you. 

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brunomusw wrote:

 Have you tried the MCP16301 Design Analyzer v1.0 ?

 The Inductor DCR and Capacitor ESR I don't know. Can be the reason? frown

 

It could be.

look at this:

 

 

 

 

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

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Ok guys... I make these changes and I'll back..
Thanks ;)

Regards,

Bruno Muswieck

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Tests done!
Guys there is no way of the MCP goes up to 370 mA. Inductor and capacitors changed.
I'm think the problem is in this IC, unfortunately I had a burned IC and this one only...

Regards,

Bruno Muswieck

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Unless it is on a proper pcb, the thing will probably oscillate and go up in smoke. Even designing the pcb is achallenge to get it to meet emc requirements.

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Kartman wrote:

Unless it is on a proper pcb, the thing will probably oscillate and go up in smoke. Even designing the pcb is achallenge to get it to meet emc requirements.

kartman, oscillate like the image on the first post? I don't belive that this is an oscillation on the output...

 

I agree about EMC requirements but right now I'm just testing and I just want to go up to 600 mA...

Regards,

Bruno Muswieck

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The image doesn't tell me much. You need to measure the switch current - this is tricky. You've got high frequencies and currents. Stray inductance due to poor circuit layout means the device will not work properly.

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brunomusw wrote:
I agree about EMC requirements but right now I'm just testing and I just want to go up to 600 mA...

 

What is your input source's output current capability?

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A controlled power supply that goes up to 3A and it's regulated at 1A.

Regards,

Bruno Muswieck

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Show us a picture of your layout. Layout and choice of components are critical for this application.

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The circuit is in a proto-board, this is the reason? Is that critical?
We did a PCB that is on the way but we will need to buy new MCP ICs :(

Regards,

Bruno Muswieck

Last Edited: Sat. Jul 4, 2015 - 01:33 PM
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Freaks we didn't test the MCP in the PCB yet but we tested the new MCP on our proto-board and we couldn't get more than 370 mA again. 

 

Then my conclusion is the PCB...

 

Thanks...

Regards,

Bruno Muswieck

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Thermal shutdown?

 

BR,

M

 

 

 

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Hum, I don't think so. It didn't get hot.

Regards,

Bruno Muswieck

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What inductor are you using? Part number of this and diode (attached to SW) and cap value and type please.

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Inductors tested: LQH3NPN150NM0L - 15 uH; LQH3NPN220NG0L - 33 uH; I build one of 22 uH that was the best result.

Diode: B130-13-F

Cap: UUT1H100MCL1GS - 10 uF electrolytic; AVE226M16C12T-F - 22 uF electrolytic; tested using 2 x 10 uC Cout too, same result.

Cboost: 100 nF ceramic cap

 

Thanks...

Regards,

Bruno Muswieck

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The LQH3NPN220NG0L you show as a 33uH is a 22uH. Page 5 of  the data sheet, table 5-1 says to use a 22uH. However, the LQH3NPN220NG0L has a Isat of 340ma. You should use an inductor with around 1.2A Isat. Minimum. Period. If you do not, it will not function correctly. Honest.

 

The diode is OK.

 

The capacitors you mention should not be used for the output of a switching power supply. Use Ceramic. They say on page 18 that the minimum values on the input should be 2.2 uF and minimum 20 uF on the output.

 

Let me know the outcome.

 

 

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The capacitors you mention should not be used for the output of a switching power supply. Use Ceramic. They say on page 18 that the minimum values on the input should be 2.2 uF and minimum 20 uF on the output.

Rule of thumb for switching power suppl use ceramic capacitors?

If yes, we're out of capacitor to test other ICs :(...

 

Sure, I will let you know... 

Regards,

Bruno Muswieck

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No. The rule of thumb for capacitors and switching power supplies, "Use what data sheet says to use." If the data sheet says ceramic capacitors are OK to use. Use ceramic. Ceramic capacitors have very low ESR. If the data sheet does NOT say ceramic are OK to use, DO NOT USE. There are older switching IC's out there that will NOT work well with too low of ESR capacitors. I can find the one part I have run into lately that fits this bill if you want a real example. 

 

I personally look for switching IC's that like ceramic capacitors as I like the life they give me. Electrolytic are too pricey in low ESR and have limited life. Tantalum explode. (Personal experience from last century.) If the parts explode on your board, even if the manufactures say they have solved the issues, I tend to stay away from them. Once burned, twice shy. I could tell you stories. 

 

Ceramic capacitors do have a tendency to be noisy. (Though my high frequency hearing is not so good anymore. Hmm... maybe the noisy ceramics caused this! :))

 

I did not say why the capacitors you had tried were no good. I read their ESR and one was many ohms. The other was not listed! If the capacitors ESR is not listed at all, it is WAY too high for a switching power supply. Even bulk might be too much for it. (Depending on the design...)

 

Have fun!

 

 

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The type and specs of the ceramics need to be carefully chosen. With the hi-k dielectrics (X7R, Y5V etc) not only can they be piezo electric ( thus making noise) they can be voltage sensitive. So a 6V part used at 5V won't necessarily give you the capacitance that is on the label. If the ic manufacturer suggests a specific part, then use that part or substitute real carefully. Size, voltage, capacitance and dielectric all have a part to play.
Once you've got the correct parts then you need to layout the pcb real carefully otherwise it will be inefficient and radiate at around 100MHz.

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Thanks guys for the tips.. I'll be more careful...

 

I bought the others MCP1630x that is 1A and 3A output, after I had tested them I'll came back... Not soon, but I'll..

Regards,

Bruno Muswieck