Guide Easy Charge and Play circuit.

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Hey everyone, about a week ago I had found a super simple one port "Charge and Play" design, it involves a P-channel mosfet, a Schottky diode, and a 100k resistor.
IMG_20170529_210451083.jpg

This requires an internal battery charger, I used a (tp5100)
The P-channel mosfet I used was an (IRF9640), the schottky diode was a (SB560A)
You can use whatever you want, as long as it's rated for the power drawn, and the mosfet needs to be a P-channel enhancement type.

When not plugged in, the 100k resistor brings the gate to ground (low), causing it to allow current to flow from battery to system load. When plugged in it brings the gate high, turning off the mosfet, not allowing current to flow from the battery, however with the schottky diode it allows current to flow from 12v in to system load with a small drop.
With the TP5100 also powered by the input voltage, the charges the battery and powers the system load with 1 jack and no switch needed.

The asterisk is there as you can use any voltage your charger/regulators can support, with pth08080's and a tp5100, my voltage range is 9-18 volts Just keep in mind that your input voltage affects output voltage from the regulators, so try to keep the input as close to the battery output as you can. (It shouldn't make too much of a difference, however.)
 
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I feel like this is too good to be true, but if someone manages to test this and get it working, I will no doubt use it in my portable.
 
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IMG_20170529_224339254_HDR.jpg
Pinout of the stripboard I'm using to test this
IMG_20170529_225323850.jpg
Battery connected charger not plugged in
IMG_20170529_225424117.jpg
Battery and charger connected, red LED shows battery is charging (would flash between red and green if batt was disconnected.)

The only downside to this over a dedicated IC made for this purpose is that this isn't as efficient (schottky diodes are pretty leaky,) when no load is applied this consumes roughly 80 microamps
 

Stitches

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Can you show a video of this setup running a system? This is quite exciting.
 
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I'll see if I can get something rigged up, I don't currently have anything that runs on 12v and 8v.

Edit:
Alright, got a chance to hook up a load, added a few things for smoothing the voltage as well.
The coil is required in this scenario, you may be able to get away without one. (sorry you hear me breath, been sick these last few days, nose is pretty stuffed)

Also heatsinks were added because these components are running a little over an amp, and I don't have a fan pointing at it.
 
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Aurelio

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I did something similar for a GC portable I was working on a while ago. It's far from being perfect, but at least it works
 
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Yup, the big issue is without a custom board the heat generated is enough to need some form of cooling.
However these small heatsinks seem to work fine in open air, might need a channel for air to move to it should you throw it in an enclosure.
 

Stitches

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Very interesting. I imagine the heat from the transistor lowers the power efficiency a tad, but the convenience of a one button/one plug power system is very tempting.
 
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If you got components rated for the exact application (15v 2 amp schottky, a higher efficiency PMOS, ect. I just used what I had lying around) there would be slightly less heat, and less leakage (because schottky's are pretty bad with that) which means less battery draw while idle.

The mosfet running the wii got warm, but most of its heat came from being right next to the tp5100, that thing got way too hot after about 20 minutes, I'm thinking that by adding the heatsinks it'll keep everything at least touchable.
 

Stitches

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If you got components rated for the exact application (15v 2 amp schottky, a higher efficiency PMOS, ect. I just used what I had lying around) there would be slightly less heat, and less leakage (because schottky's are pretty bad with that) which means less battery draw while idle.

The mosfet running the wii got warm, but most of its heat came from being right next to the tp5100, that thing got way too hot after about 20 minutes, I'm thinking that by adding the heatsinks it'll keep everything at least touchable.
Maybe that's what Nintendo did with the Wii U gamepad. Would explain why it holds charge for barely 5 minutes >.>
 
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