Problem with LTC2942

Good afternoon everyone from Spain,

I'm Juan Domingo, from GTG Ingenieros.

We have used the LTC2942 in the design of an electronic card for a portable device. We have connected this IC as indicated in the datasheet. Schematic in pdf file is attached.

This device is powered from a 1-cell Li-Ion battery. It is a removable cylindrical battery; therefore, it is possible that, when removing the battery, the polarity of the battery can be inverted when it is inserted next.

We have verified that, by reversing the polarity of the battery, the LTC2942 burned and stopped working altogether.

I make the following queries:

1) .- Does the LTC2942 have some type of polarity inversion protection?.

2) .- Could you explain to me what caused this problem?.

3) .- Given that it is possible that a polarity reversal of the battery occurs, could you tell me if this is appropriate battery monitor or recommend another better reference?

While waiting to receive your answers, I appreciate your cooperation.
Sincerely,
JuanD

PMIC SCHEMATIC.pdf

    •  Analog Employees 
    on Dec 4, 2018 5:55 AM

    1) LTC2942 does not have reverse polarity protection.

    2) LTC2942 has internal ESD protection diodes, e.g. from GND (anode) to SENSE+. Applying reverse polarity will cause a big forward current through this diode and damage the part.

    3) You need some reverse polarity protection device e.g. LTC4365

    https://www.analog.com/en/products/ltc4365.html#product-overview

    Or you built your own discrete with a single PMOS, just search for "pmos reverse polarity protection", there are tons of examples available.

  • Hi Patrick,


    Thank you very much for answering. Your recommendation is smart, but I think it will not be appropriate in our case. Next, I provide more information about our work scenario:

    1) .- The battery we use is connected to a battery charging IC from Analog Devices (LTC3555). If we use a reverse polarity protection device (LTC4365, or similar), this device will not allow current circulation for charging the battery.

    2) .- In the different tests carried out, we have verified that, on some occasion, the LTC2942 is also damaged when inserting and extracting the battery with the correct polarity.

    3) .- The LTC2942 is used to measure the battery voltage and communicate via I2C with a microcontroller.

    Any ideas for solving this problem?.

    Is it more appropriate

    Will be better to use an IC battery monitor with high-side or low-side current sensing?

    Thanks in advance,

    JuanD

    •  Analog Employees 
    on Dec 10, 2018 11:24 PM in reply to GTG_I+D

    Hi JuanD,

    Please contact local ADI support team who can assist to understand more your applications.