I am working on a circuit design and have run into a problem I am unsure how to address. My design leaves me in a situation where I need to have a charge pump (LTC3204-5) outputting 5V connected to my devices voltage output line. However, this same line may in certain situations be connected a a voltage input when connected to an external device.
My design is a for a handheld transmitter that connects to various sensors for data collection and communication. The issue arises from the fact that some of the sensors have their own internal power which would be supplied to my handheld on the same line as my charge pump is outputting.
The charge pump has a 5V output and a 5.5V max on the output pin connected to the voltage line. The sensor may put out up to 12V which would surly fry my charge pump.
I have considered a diode to prevent current flow, but the charge pump chip manufacturer's FAE indicated that the voltage present would likely still cause issues despite a lack of current.
As a result of all of this, I need to design my circuit such that voltage can go out of my handheld, but that it is not able to to enter and cause damage to the internal circuitry.
I am currently thinking of putting a load switch (FDG6324L) in line which can handle voltages in excess of 12V on the output pin, but would stop the voltage from going out the input pin. I would design this switch to be constantly turned on and simply be using it as a voltage block. I am not sure if this will work (It was suggested to me by another engineer) and am in the process of getting samples to test.
Please let me know if you have a way to design this circuit simply or have any other suggestions as to what I may do about this situation. I am running out of time and ideas and need to finalize this power supply design in the next week. Any feedback would be much appreciated.
Those part numbers appear to be non TI, so I really do not have any advice about their operation. Have you considered any TI solutions? If you post your design specifications, I may be able to help.
Consumer DC/DC Applications
I realize those are not TI parts. What I am looking for is a TI part that would satisfy the requirements that I outlined above. I need something to block the 12V sensor supply form damaging my internal circuitry of the device. I am not sure if a simple diode solution would work and was wondering if there was a protection chip that would be able to take voltage from my device output and from the sensor output on the same line and prevent the sensor's output from reaching the rest of the circuitry.
Thanks for the reply.
Well, I don't understand why a simple diode would not do the trick. If you decide to use TI parts to make the solution, you can put a circuit and I will comment. Or, you can put a block diagram for us to offer suitable parts.
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