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Can I power up a 18F pic and a 16*2 LCD with Energy harvesting IC (LTC3588 breakout) ? Answered

I want to make a heart rate sensor which is attached to a shoe. Instead of using batteries, I have thought of using LTC3588 breakout IC for my project. I use a piezo-plate to give the signal to LTC3588 IC, from that i hope to generate a current and voltage to drive my cct and the 16*2 Lcd. For Heart rate sensing, I use a IR sensor in the shoe. From the piezo plate, the foot steps can be calculated and find the distance the wearer traveled. 

will this work? If u have any suggestions or any ideas or the changes that I should make, Pls don't hesitate to write.

Thank You

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steveastrouk (author)2012-08-11

Dunno. The maximum o/p current of the 3588 is certainly more than enough, but the O/p volts is only 3.6V max, which won't run most of the 16 x2 displays I know of, so you'll need to add another switcher to boost it for the display. Could you handle a bluetooth transmitter, and beam the signal to your phone instead ?

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Kevindu_CK (author)steveastrouk2012-08-11

Yes I can do that too. That was my backup plan, in case i won't be able to generate enough current and voltage for my cct. But don't u need more voltage and current for a bluetooth transmitter? would it be better if I use small RF transmitter ? Zigbee ? Isn't it low power consuming?

Max out put of LTC3588 is 100mA. Is it going to be enough for my work?

btw thank you for the answer. I appreciate it.

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steveastrouk (author)Kevindu_CK2012-08-11

100mA should be easily enough...if you can generate it....I'd want to set up experiments to measure the available power before I started designing the rest of the project.

Zigbee's great - but you probably have a phone with its own receiver in it already. BTs not great for power economy - its not BAD though. The quiescent current can be as low as 250uA, then it would burst data to the receiver, taking maybe 25mA.

Steve

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Kevindu_CK (author)steveastrouk2012-08-11

I see what u mean. wouldn't that be the same case when it comes to blue tooth? I mean wouldn't it take nearly 25mA to burst data to the mobile?

Have you ever worked with LTC3588? I was thinking of using a super capacitor to store the current for the cct to work for a longer period? What do u think of it?

I haven't tried it yet, but I really need an opinion regarding that if u have tried LTC3588 breakout board.
I really want to successfully finish my project.

thank you

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steveastrouk (author)Kevindu_CK2012-08-11

You can use the chip, but it cant generate power from nothing. By all means, try a super-cap, but first of all, make some measurements !!!

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Kevindu_CK (author)steveastrouk2012-08-11

I am using a Piezo plate to generate a signal to the IC.

Thank YOu for the help. I will try it.

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steveastrouk (author)Kevindu_CK2012-08-11

Pump up a capacitor. energy stored = 1/2 x C x V^2

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Kevindu_CK (author)steveastrouk2012-08-11

yeah... but when it comes to the point where i have to gradually discharge 10F super cap using a load resistor, I am not sure.... :-/

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steveastrouk (author)Kevindu_CK2012-08-11

What's the problem ? There's a maximum of 3 V present. Supercaps are good, but they can't deliver infinite current, so you aren't going to disappear in a puff of smoke. Discharge it with a 1 Ohm resistor - it will take 10 Seconds, and dissipate a maximum of about 10 W.

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