We are looking for a battery charger chip, capable of handling charging a power bank through USB-C. Moreover, it needs to be able to also use the USB-C connector for a standard wall mount power supply.
Scenario 1:
Standard scenario, where the device is connected to an input source, capable of delivering 5-40V. In this scenario the input power is patched to the system load and if a power bank is connected, then its charged.
Scenario 2:
The input power source is removed. The system load is using the power bank.
Scenario 3:
The input source is removed, but instead of a power bank a standard 5V wall socket USB-C power supply is used.
We have been having a hard time finding the appropriate IC, since most IC’s use the USB-C input to power a battery and not to connect the battery to the USB-C input.
Thank you for contacting the MPS Forum. We really don’t have a lot of charging devices capable of handling 40V input. I would say the max we can do right now is 36V with the MP2759. I’m not sure what you mean by connecting the battery to the USB-C input, can you explain the difference of that from using the USB-C input to power a battery? I think that anything with power path management could potentially achieve this if I am interpreting things correctly. Please let me know and I will do my best to help you out, but at 40V input you will either need to use a 2 stage solution or try to use 36V max for the MP2759.
Thanks,
Brendan Schoemehl
Field Applications Engineer
Monolithic Power Systems | MPS Now
Thank you for getting back to me on this. There is a high chance that my understanding of the power path setup is just good enough or that I’ve misunderstood the functionality. So let me try to explain better.
Looking at the application layoyut for the MP2759, what we want to achive is to create a setup where our standard port/connector for the battery is an USB-C port, so that different types of powerbanks can be connected. This is fairly simple and this should be possible. But the questions goes mainly towards Scenario 3 from above. If we have a USB-C connector, meant for connecting powerbanks, can we then also use the same connector to connect a standard power source (like a 5V wall plug connector). I’ve tried to picture it here, use the application layout for the MP2759:
So the USB-C connector would be the input source for the IC and also be an output for the battery? This conflicts with what you say by “can we then also use the same connector to connect a standard power source” as this would now be an input not an output. That is where I am confused. The scenario 3 drawing looks identical in use case to scenario 2 to me. You could certainly use any type of USB power to charge a battery, even with a battery IC charger.
Scenario 1 is where I would be most concerned about. You would need to regulate separately from the input to the USB-C power bank, the battery charger will not have 3 outputs just 2 (SYS output and Battery).
The power path on this device allows you to output both to the system and to the battery at the same time. It would also allow the battery to output to the system. It controls where the power heads in the system. If you wanted to connect multiple inputs to the device, you could either diode OR the inputs or you could make sure the USB-C connector you choose allows a non-usb 40V signal to pass through. The IC would then regulate for the charge voltage you need.
We may need a 2 stage solution to drop the 40V down to a more reasonable voltage for our battery charger IC. Doing so would allow us to recommend a different battery charger as well. Can you tell me the specs of your battery?
Thank you for the detailed explanation. We appriciate you taking time to do so.
The system does not always have a battery (power bank) connected. The idea is that this can be an option for the user, if they want to add UPS functionality.
If a battery is connected, then this is scenario 2.
When there is no battery connected, then the USB-C connector could also be used for normal power from a 5V power source. This is scenario 3. The product is typically installed remotely, but when we are testing it, its nice to be able to just power it from a standard USB-C wallplug power source. The easiest solution would just be some kind of passthrough of the power from the USB-C connector to the load, in this scenario. But I’m unsure if its possible.
We can drop the voltage below 40V with another stage, if needed. I dont know if it changes the options we have.
I think many of our power path devices can work as a pass through to the load when the battery is already charged. Can you tell me the following specs you need to meet?
Charge voltage
Charge current
Output (system) voltage
Output (discharge) current
I’ll try to come back with a few device suggestions based on this for you.
Thanks,
Brendan
Thanks Biff, I will begin looking for a device for you. What battery are you using that requires a 5V charge voltage? This is not a standard charge voltage for our battery charging devices, so this may complicate things.
Not sure what your discharge current is, if your system output needs more than 500mA then something like the MP4570 is a good device. This is a high voltage buck converter, capable of powering 3A load. If you need something higher in current capability, the MP4575 (5A) is a good option
For the battery charger, I would suggest the MP2617B to start with. It’s a power path battery charger with pretty basic features, a good base line. I notice you say your system voltage is 5-40V…does this mean your output is 40V max? We would need to boost off your battery if that was the case.
Let me know your thoughts with these initial devices. You can always email mpsnow@monolithicpower.com to get quicker responses as well.
Thanks,
Brendan
