Hot Swap Battery Controller Recommendation

Nicholas Zambetti

Other Parts Discussed in Thread: BQ25622, TPS25948, TPS2400

I am hoping to find some recommendations for ICs that would work well with the BQ2562X series and allow for safe hot swap of battery packs...

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1288843/bq25620-hot-swap-battery/

Might anyone be able to point me in the right direction and/or share some reasoning about how to select an appropriate one?

Thank you,

Nicholas

8 months ago

0 Kunal Goel 8 months ago

TI__Guru 55390 points

Hi Nicholas,

What are the voltage and current requirement?

Regards

Kunal Goel

0 Nicholas Zambetti 7 months ago in reply to Kunal Goel

Prodigy 170 points

Hi Kunal,

I am using an LFP battery pack 3.2V with a maximum discharge current of 5A.

The BQ25622 charge current is 3.5A max.

Thank you for your help,

Nicholas

0 Kunal Goel 7 months ago in reply to Nicholas Zambetti

TI__Guru 55390 points

Hi Nicholas,

You can check TPS25948 device.

Regards

Kunal Goel

0 Nicholas Zambetti 7 months ago in reply to Kunal Goel

Prodigy 170 points

Thank you Kunal, this looks like a very useful IC.

Question 1.

To protect the system during battery disconnect/reconnect, should the EN pin simply be tied to VBAT?

Or should the EN pin be activated after some delay when the battery pack is attached?

Question 2.

The 3.2V LFP battery pack has a has a voltage range of 2.5-3.65V, and protection for over discharge detection voltage at 2.1±0.05V.

The TPS25948 has a VUVP(F) IN supply undervoltage protection falling threshold of 2.2-2.4-2.65V.

This does provide some headroom, so I will likely leave it at the default; but do you think that it might be a good idea to lower the UVLO threshold using the voltage divider as mentioned in §8.3.1. Does this seem like perhaps a good idea considering the minimum voltage of the battery?

Many thanks,

Nicholas

0 Kunal Goel 7 months ago in reply to Nicholas Zambetti

TI__Guru 55390 points

Hi Nicholas,

Can you share basic block diagram of your representation?

You can control EN pin they way it suits your need. We can not lower UVLO beyond UVP will be bottleneck here. Assuming there is a resistor divider from VIN to EN and VIN is falling, so UVP will happen first and disable device. Similarly when VIN is going up even if VIN goes above UVLO, device will enable when VIN goes above UVP.

Regards

Kunal Goel

0 Nicholas Zambetti 7 months ago in reply to Kunal Goel

Prodigy 170 points

Thank you Kunal,

The TPS25948 seems to be tuned for 3.7V Li-Ion/Poly batteries where the over discharge voltage is 2.4V.

It is good to know that the UVLO threshold cannot be lowered, since that means that the battery run-time will be shortened unnecessarily when using the TPS25948 with the newer 3.2V LFP battery packs.

Does TI offer a similar IC but with a lower (or more configurable) threshold?

I've drawn a high-level system block diagram as you requested...