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LM66100: Cascading batteries in parallel using Ideal diodes

Art Mecina
Genius 16655 points
Part Number: LM66100
Other Parts Discussed in Thread: TPS2116

Hello Guys,

Good day.

Our customer is  designing a project where the idle current is around 100uA but about every hour it consumes around 100 to 150mA for a brief period.

They need to design a battery solution which will last 5 years. They are looking at using several LM66100DCKR IC's combining 6 Fanso ER3416H Lithium Thionyl Chloride batteries. In reviewing the data sheet he notice that if he connect the !CE pin to the VOUT pin it will provide Reverse current from flowing. In the data sheet there is a note stating that if you use the same voltage sources in this configuration that there is a possibility that they can all shutdown due to similar voltage levels. This actually is ok in their design concept. Refer to the attached partial schematic. In this schematic you will note that they are charging a LI-ION capacitor (very low leakage) to the 3.6V battery. Once this capacitor is charged (to the highest battery voltage available) they really don't care if the Ideal diodes turn off.

Do you see any issues with what they are attempting? The schematic only shows three batteries but their target is using 6 in a similar configuration.

Ideal Diode.pdf

Thanks in advance!

Art

  • 0
    TI__Mastermind 32650 points

    Hi Art,

    We do not recommend using LM66100 in a load sharing application like this. There is a situation where more than one device could be active causing short between two batteries of different voltages. This could be a low current connection which may be enough to damage the cell but not enough to trigger the RCB.

    It might be possible to use power MUX devices that select the highest voltage to send to the output but this will require some sort of cascaded topology of multiple powerMUXes. I would suggest looking at TPS2116.