Hi,
we are experimenting some problems with bq2409x battery charger.
In one of our device we are using 3 supply methods and one of this is a lithium battery charged from bq2409x.
The device is an EEG recorder that is connected to a patient so once in a while ESD are present at patient input.
In places where ESD are frequent damages to the bq2409x have happen so that no battery charge
is performed anymore and current consumption is higher than normal, also chip temperature on the case can reach 150°C.
This event happened on 10% of the device in use in those places.
So we have tried to repeat the problem in house using a ESD gun with 9KV discharge on patient input.
But first trials have caused the disruption of components other than BQ2409x typically FPGA and Input amplifier, so we should consider also other problems different from ESD.
We have traszorb protection on patient input and also a 3KV gas discharger that bypass the isolation barrier.
In the datasheet the BQ2409x has ESD Ratings of 3KV (HBM) though there is a recommendation to consider ESD handling the device.
Actually in the layout we don’t have close capacitor to the chip supply nor clamp to the voltage on IN, OUT or CHG, PG Pins that we intend to add to consider extra voltages beside ESD.
Does anyone have problem with BQ2409x broken?
Is there any known specific measure to adopt to preserve the bq2409x functionality?
The power supply scheme is attached.
Thanks for attention
Matteo Sarto
