My Synchronous Buck MOD (.591-6.0V with > 95% efficiency @7V input)

[CapeCAD]

Been using this Synchronous Buck .591-6.0 Volt mod with > 95% efficiency at 7V input for 2 weeks now. batteries last me 3 days between charging.

Using a Murata Power Solutions OKR-T/3-W12E-C DC/DC converter: http://search.digikey.com/scripts/DkSearch/dksus.dll?site=us&lang=en&mpart=OKR-T%2f3-W12-C

This converter does not require external capacitors for our application, but I used 10uF ceramic capacitors for optimal performance.

Enable pin does not require high current switch.

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600 KHz operation​

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4.5-14 Vdc input voltage range​

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Programmable output voltage from 0.591-6.0 VDC​

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Drives up to 200 μF ceramic capacitive loads​

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High power conversion efficiency at 93%​

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Outstanding thermal derating performance​

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Over temperature and over current protection​

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On/Off control​

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SIP, 0.41 x 0.65 x 0.22 inches​

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This was my first adjustable mod​

First PCB Design .410 diameter

First prototype

Tightest packaging with new PCB and SMD components

I'm looking for a good SMD led now for maximum density.

 

[youtubecommercial]

Very nice! I love a 3 day + vape

 

[Scubabatdan]

Very cool, you could add a 200k POT to adjust the voltage on the fly rather than use a 218ohm resistor for a set voltage of 6v. You can get one here:
Digi-Key - 3299Y-204LF-ND (Manufacturer - 3299Y-1-204LF)
That way you can use it for LR standard or HR attys.
Just an idea to expand your awesome design
Dan

 

[CapeCAD]

My 3 days usage is using 1 ml per day. Not sure how that compares

Very cool, you could add a 200k POT to adjust the voltage on the fly rather than use a 218ohm resistor for a set voltage of 6v. You can get one here:
Digi-Key - 3299Y-204LF-ND (Manufacturer - 3299Y-1-204LF)
That way you can use it for LR standard or HR attys.
Just an idea to expand your awesome design
Dan

I use a 1K pot, the 218 ohm resistor in series with the pot is to insure that the voltage does not go above 6V or below 1.5V.

Here are the trim values:
6 V. 218.5
5 V. 268
3.3 V. 436
2.5 V. 619
1.8 V. 978
1.5 V. 1300
1.2 V. 1940
1.0 V. 2890
0.591 V. ∞ (open)

 

[Rocketman]

Yup, another high frequency charge pump, and the digikey prices don't look bad either.
Have you tried to see if you could pick up your mod on the AM radio (without the bigger caps)?

This looks like where high voltage, adjustable mods are headed.

Good job.

(remember that published efficiency values, may be different than total circuit efficiencies)

 

[Sci]

I'm looking for a good SMD led now for maximum density.

1st off, great job on this. This has potential for so many things. Looks like it could actually be mounted to the battery connector?

2nd, where did you get that voltage display?

Finally, not sure if these are exactly what you are looking for(SMD LEDs), but there are a lot of different kinds & some are as cheap as $.05ea(min. purchase of 10).

 

[WillyB]

Seems great as is the price of the chip. But reading the specs I see this:

 Vin must be 2V or higher than Vout for 3.3 to 5V outputs.

So to vape @ 5V your batts need to be at 7V? Am I reading this wrong?

 

[CapeCAD]

1st off, great job on this. This has potential for so many things. Looks like it could actually be mounted to the battery connector?

2nd, where did you get that voltage display?

Finally, not sure if these are exactly what you are looking for(SMD LEDs), but there are a lot of different kinds & some are as cheap as $.05ea(min. purchase of 10).

Thanks. This PCB is intended to be used in a 9 led flashlight 3 AAA battery holder with (2) 10440 batteries and room for pot and momentary switch.

I do have an inline battery connector design on the drawing board.

I am using a Murata Power Solutions DMS-20LCD-0-DCM-C voltmeter (LCD will shut down when input voltage is too low)
DMS-20LCD-0-DCM-C @ 3½ Digit, Self-Powered LCD Digital DC Voltage Monitor: +6.50 to +18.00Vdc Input @ Murata Power Solutions

I did locate some 1206 size SMD LEDs and have one installed in place of the through hole LED, thanks
Digi-Key - 350-1565-1-ND (Manufacturer - 597-3111-407F)

Seems great as is the price of the chip. But reading the specs I see this:
So to vape @ 5V your batts need to be at 7V? Am I reading this wrong?

That was the first thing I questioned. All specifications are application specific:
Under full load, with no thermal derating and continuous operation, I can understand why Vin 2V over Vout would be a requirement. I suggest talking to an application engineer before attempting to use any component outside of it's published specifications.

Note: Vout will drop when Vin is less than 2V over Vout, but this is near the end of the battery life when used at 5V output. It's based on duty cycle so I don't know the exact drop-off, I don't notice it myself but will test it when my batteries are lower.

Our requirements for vaping are extremely easy on a DC/DC converter with this thermal performance (My batteries are fully drained when it shuts down.)

 

[SurvivorMcGyver]

Thanks for sharing.

Good to see someone use this in practicality. I got 2 samples of this chip direct from Murata over 6 month ago and have yet to inplement it -- Guess I better get on it eh?

How stable is it under load (set volt VS voltage under load)?

(I quess my resistance to pursue this has been my focus designing around HV atties - 4.9 and above - due to the lower amp draw - so the output is simply too low Athough ....... I have reserved it to design a passthough for when I'm traveling -- pluged into 12V)

Let us know how the loaded voltage stands up and what atties you've used it with.

 

[CapeCAD]

Thanks for sharing.

Good to see someone use this in practicality. I got 2 samples of this chip direct from Murata over 6 month ago and have yet to inplement it -- Guess I better get on it eh?

How stable is it under load (set volt VS voltage under load)?

(I quess my resistance to pursue this has been my focus designing around HV atties - 4.9 and above - due to the lower amp draw - so the output is simply too low Athough ....... I have reserved it to design a passthough for when I'm traveling -- pluged into 12V)

Let us know how the loaded voltage stands up and what atties you've used it with.

Note: They offer a 6 Amp and 10 Amp version that's pin compatible with this converter.

My experience so far has been with Vapor4Life Carts and a standard 901 atty from MadVapes, all measure in at ~3.2 ohms.

I'll run some tests and publish the results

 

[SurvivorMcGyver]

Note: They offer a 6 Amp and 10 Amp version that's pin compatible with this converter.

My experience so far has been with Vapor4Life Carts and a standard 901 atty from MadVapes, all measure in at ~3.2 ohms.

I'll run some tests and publish the results

looking forward to it -- My package has a Murata P/N is 4941098 -- need to dig for my specs!

 

[bigblue30]

Been using this Synchronous Buck .591-6.0 Volt MOD with > 95% efficiency at 7V input for 2 weeks now. Batteries last me 3 days between charging.

Using a Murata Power Solutions OKR-T/3-W12E-C DC/DC converter: http://search.digikey.com/scripts/DkSearch/dksus.dll?site=us&lang=en&mpart=OKR-T%2f3-W12-C

This converter does not require external capacitors for our application, but I used 10uF ceramic capacitors for optimal performance.

CapeCAD,

Very nice package and well done. It looks to me like the old "hot" regulators are not going to be used much longer.

Great find and a much better price then the one I used and the same pin out.

http://www.e-cigarette-forum.com/forum/battery-mods/114901-evercool-variable-voltage-mod.html

Is that the "e" version with the control pin going "low" to turn it on?

 

[tmbrown327]

Nice. Looking forward to how you package this. At the end of the day, that's what's going to be in our pockets.

 

[CapeCAD]

I am using the E version, which turns on when the control pin is tied to ground. I use a "normally open" low amperage switch.

The standard version (also identified as 4941098 above) is on by default and shuts off when the control pin is tied to ground which will work with a "normally closed" low amperage switch.

 

[bigblue30]

I am using the E version, which turns on when the control pin is tied to ground. I use a "normally open" low amperage switch.

The standard version (also identified as 4941098 above) is on by default and shuts off when the control pin is tied to ground which will work with a "normally closed" low amperage switch.

CapeCAD Thanks, I wish the TI chips would do that.

 

[WillyB]

I am using the E version, which turns on when the control pin is tied to ground. I use a "normally open" low amperage switch.

The standard version (also identified as 4941098 above) is on by default and shuts off when the control pin is tied to ground which will work with a "normally closed" low amperage switch.

Would be nice to use my favorite NO switches in a low current mode.

Have no idea where you found a OKR-T/3-W12E-C though, as none of their distributors carry such a number. And although Murata lists it in their spec sheet that part number produces zilch.

OKR-T/3-W12E-C @ Results @ Search @ Murata Power Solutions

Murata Power Solutions

 

[tmbrown327]

I backed it down to OKR-T/3-w12 and got this:
OKR-T @ Results @ Search @ Murata Power Solutions
The E version is a variant in the datasheet.

 

[Rocketman]

I'll run some tests and publish the results

Looking forward to the test data. Nice job (both of you guys).
Linear regulators will never go away. Cheap, but they are wasteful, and definitely not the way to get the most out of portable battery devices.
Just like transformer wall warts. Why are they still here?

Rocky

 

[CapeCAD]

Batteries died, let them sit for an hour to recover, measured 6.51V input and 4.99V output then shut off after 4 seconds and measured 2.75V each with no load.

Fresh 14500 batteries measuring 4.2V each with no load after charge
Using RS Digital Multimeter with 2.5 Ohm cartomizer (It's all I have) and the same 2 batteries:

Mod 1 wired in directly
Input
Volts 7.75
Amps 1.42
Watts 11.005

Output
Volts 4.99
Amps 1.95
Watts 9.7305

Efficiency 88%

Mod 2 with PCB
Input
Volts 7.73
Amps 1.44
Watts 11.1312

Output
Volts 5
Amps 1.98
Watts 9.9

Efficiency 89%

I'll continue to test over the next few days as the batteries drain

 

[Rocketman]

The values you got seem quite reasonable. The 2.5 ohms and 5 volts is probably close to the efficiency peak at that input voltage. I hope everybody noticed the similar results blue got with his chip.
Close to 90% of the battery energy (instead of 60%) is going to vaping. Those mah hours saved will go straight to extra time on the batteries and a lot less heat in the electronical parts. I like seeing good engineering work. You guys keep having fun.

Rocket