TPS25981: UV and OV protection of battery with bidirectional switch with eFuse

Prithvi Raj Narendra1

Part Number: TPS25981
Other Parts Discussed in Thread: TPS25947, TPS25948

Hello,

This article describes how bidirectional switch can be developed with eFuses for use with a battery. https://www.ti.com/lit/an/slva948/slva948.pdf

Can the the UVLO and OVLO pins of chips like TPS25981 be used to prevent discharging and charging respectively to protect a battery from deep discharging or over charging?

Regards, Prithvi

4 months ago

0 Arush Gupta 4 months ago

TI__Genius 14610 points

Hi Prithvi,

TPS25981 is a single FET device and cannot provide reverse current blocking (RCB). You can use UVLO or OVLO pins to limit the voltage from input side to output side of the device but cannot stop discharging as discharging will happen through reverse current. Overcharging can be prevented as the device can cut off the power when the voltage goes beyond the set OVLO limit.

Best Regards,
Arush

0 Prithvi Raj Narendra1 4 months ago in reply to Arush Gupta

Intellectual 550 points

Hello Arush,

In the article that I linked in the previous post, by connecting them back to back we can have reverse current blocking. In such as case I feel using the UV in the IC connected to battery and OV in IC connected to charger should work. Can you please double check? Thanks.

0 Arush Gupta 4 months ago in reply to Prithvi Raj Narendra1

TI__Genius 14610 points

Hi! Prithvi,

Earlier I thought you were trying to achieve this using single eFuse. Yes, you can use the method which you mentioned. Effectively UV is Enable and OV is Enable bar pin and you are trying to turn them on or off to achieve RCB.

I would recommend TPS25948 or TPS25947 devices. They come with back-to-back integrated FET and also provide RCB control. Please check their datasheet also.

Click resolved if no other follow up question.

Best Regards,
Arush

0 Prithvi Raj Narendra1 4 months ago in reply to Arush Gupta

Intellectual 550 points

I would like to use two individual eFuse in series to be able to either allow only charging or discharging or both. For this it'll need the current to flow through the body diode of the MOSFET. I am not able to find the continuous current rating of the body diode. Can you please help with this?

Thanks, Prithvi

0 Arush Gupta 4 months ago in reply to Prithvi Raj Narendra1

TI__Genius 14610 points

Hi Prithvi,

I will get back to you after aligning on this with our design team.

Best Regards,
Arush

0 Arush Gupta 4 months ago in reply to Arush Gupta

TI__Genius 14610 points

Hi Prithvi,

Can you tell me how much current you are expecting. Based on that we can tell if the device can sustain that or not.

Best Regards,
Arush

0 Prithvi Raj Narendra1 4 months ago in reply to Arush Gupta

Intellectual 550 points

I'm looking at 3.5A current at most. Thanks.

0 Arush Gupta 4 months ago in reply to Prithvi Raj Narendra1

TI__Genius 14610 points

Hi Prithvi,

Will it be continuous 3.5A or for some short duration (any estimated value)?

Best Regards,
Arush

0 Prithvi Raj Narendra1 4 months ago in reply to Arush Gupta

Intellectual 550 points

It'll be continuous since it is battery charging. Let me know if its a lower value, what is acceptable. Thanks.

0 Arush Gupta 4 months ago in reply to Prithvi Raj Narendra1

TI__Genius 14610 points

Hi Prithvi,

I have asked this to the designer of this eFuse. I will get back to you when I get response from them.

Best Regards,
Arush

+1 Arush Gupta 4 months ago in reply to Arush Gupta

TI__Genius 14610 points

Hi Prithvi,

I got reply from the designer of this part.

3.5A continuous current is very high. In general, continuous current is not recommended through the body diode. Even assuming 0.8V drop across the diode, we will get 2.8W continuous power dissipation which is high.

Best Regards,
Arush

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TPS25981: UV and OV protection of battery with bidirectional switch with eFuse