charging circuit and fuel gauge combo

The are several options available.  The most simple solution is the MAX17332 with is a fuelgauge/protector/linear charger in a single IC.  We also have fuel gauge/protection ICs like the MAX17300 that can be used along side the MAX77818.

Please let us know if there are any additional questions/details to share on your application .

Hi - 

I already implemented the MAX17201 fuel gauge simply because I am familiar with it and already have firmware from a previous product design.   Currently I have an Intersil charger implemented (while I was waiting for feedback).  

However enticing the MAX17332 seems, I could not find any example C++ code on GitHub with regards to this IC. As I am mostly hardware designer, it is easier for me if I can find some code/libraries that I can customise. 

I am using a single cell Li-Po with Particle B524 uC in this design.  Would you recommend I stay with the MAX17201 or maybe go with a seemingly more simple device such as the MAX17048G.  Currently I have the Li-Po cell connecting to the MAX17201.  I have the charger IC next connecting to System GND and V+ of the cell.

Regards,

Friedl.

Hi Friedl,

The MAX17332 is included in this driver:  https://www.analog.com/en/design-center/evaluation-hardware-and-software/software/software-download.html?swpart=SFW0006130D

If you want to stick with the fuel gauge only device, the MAX17201 is a very good choice for our Model Gauge m5 fuel gauge.  The MAX17048 is a much simpler device, but it is our voltage only Model Gauge fuel gauge.  So depending on the level of accuracy you need from your fuel gauge, the Model Gauge m5 will provide a more accurate fuel gauge as it combines our voltage fuel gauge with coulomb counting to provide a best in class fuel gauge.

Thanks,

Jason

Hi Jason - 

Thank you again for the response and patience.  Honestly I would have preferred to go with the MAX17332 my only concern would be whether I would be able to complete the firmware development as I am not a programmer.

I had a brief look at the .C driver file.  I noticed the Max17201 is also listed in the code, is it the same driver?  If so, I might be able to get it working with the firmware I have for the MAX17201.  If the registers I need to read are the same, chances are good.

With regards to the MAX17048 - In this application accuracy is not crucial.  These will be simple RFID readers placed at venues, so no planes will be dropping out of the sky if it is off by couple of percent :)   My only question with the MAX17201 would be whether I implemented it correctly.  Currently I have the battery connecting to the MAX17201.  The 'other side' of the MAX17201 provides the System_GND which is then connected to the charger.   I assumed that if the charger was connected to the 'battery GND' the coulomb counter would not be accurate as it would not count coulombs going back into the battery from charging? 

Regards,

Friedl

Hi Friedl,

Yes, the same driver is used for a variety of our ICs, including both the MAX17201 and MAX17332.  Some of the register definitions and locations have changed between the two devices, but the different locations are handled in the driver.  Both can have their settings configured into NVM.  The EVKIT GUI of each is the best way to configure the Non-Volatile Memory file.

The connection of your charger to the SYS GND side of the sense resistor for the MAX17201 is correct.  We want all of the current to flow across the sense resistor so that fuel gauge can measure the current.  On the MAX17332 the sense resistor has been moved to the high side.

The MAX17048 might still be a good option for you.  There is a default model that may provide a good enough accuracy for your application without requiring a custom model that would need to be loaded at each power cycle.

Thanks

Hi - 

Ok thanks!!  I think for this application I will consider either MAX17201 or MAX17048.  Depending on the cost, I will try to get an EV-kit for the MAX17332 as it seems like a really nice component to use on future projects!

I will look at both MAX17201 and MAX17048 tomorrow and then implement one.  I mostly used the MAX17201 as I almost exclusively use Li-SOCL2 or Li-MnO2 cells.   This time however it will be standard Li-ion or Li-Po, which is why I thought U could look at a more simple solution. 

Many thanks, have a good weekend!!

Friedl

Hi Jason - 

We received out prototype boards and I started testing.  So far all good, I just have one question of you do not mind.

The device has been on charge for a while, I am publishing data from the fuel gauge every 60s to monitor during this testing phase.  At any given point the statistics were as follow: 

Cell temp: 27.36C -- Cell V: 4014.06mV -- Current: 534.84mA -- SOC: 68.47

I then reset the device.  The of course means setup() in the code will run.  In the setup is a line of code as follow:

gauge.reset(); 

The first post after the reset had the following result:

Cell temp: 27.72C -- Cell V: 4016.41mV -- Current: 534.22mA -- SOC: 53.96%

Everyting makes send but the SOC does not.  Is this to be expected?  In makes me question the reason for the gauge.reset() code in the setup.  Is this necessary?   Aside from this all is well!

Regards,

Friedl