BQ34Z100-G1: datasheet clarification regarding reset

David McRell

Intellectual 445 points

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO, EV2400, BQ34Z100

Hello TI,

A two-part question

1) from this old thread:

e2e.ti.com/.../213047

In the paragraph titled "Reset Functions" the data sheet talks about a harware /MRST pin. This pin is not shown in the pin descriptions table. Is this an error or does one of the pins actually have this function.

It appears this remains in the G1 version of the datasheet, yes?

2) If there is no hw-based reset, then is the only way to perform a reset via Host I2C/HDQ control, or will removal of battery power (i.e., deeply discharged battery) also cause reset?

Kind Regards

David McRell

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi David,

Yes. BQ34z100-G1 doesn't have the /MRST pin either. You will need to perform a software reset.

Andy

0 David McRell over 5 years ago in reply to Andy Liu (BMS)

Intellectual 445 points

One more question if I may?

Is the BQ34z100-G1 truly standalone?

The parametric search here:

ti.com/power-management/battery-management/fuel-gauges/products.html

mentions "standalone", but datasheet does not mention it.

Goal: we are looking for single cell, ~2000 - 4000 mAh Li-ion, system-side, standalone gas gauge that can show state of charge on 3 LEDs.

Kind Regards,
David McRell

0 Andy Liu (BMS) over 5 years ago in reply to David McRell

TI__Guru 52115 points

BQ34z100-G1 is a fuel gauge and has no protection feature. If it is what you are looking for, I think it seems like a proper gauge.

Andy

0 David McRell over 5 years ago in reply to Andy Liu (BMS)

Intellectual 445 points

If the BQ34z100-G1 has its parameters programmed at factory via BQstudio+EV2400, but then out in the field the battery is deeply discharged and causes it to electrically disconnect from system, will the 34z100 need a host to (re)initialize it?

David

0 Kang Kang over 5 years ago in reply to David McRell

TI__Mastermind 24870 points

Hello David,

No, it is a flash gauge. POR will not cause any issues. However, as you are charging the cell from a depleted state and the bq34z100 powers up, it could measure a bad OCV on the first cycle. Make sure that the bq34z100 eventually has a way to take an OCV to correct a possible bad initialization.

0 David McRell over 5 years ago in reply to Kang Kang

Intellectual 445 points

Kang Kang said:
as you are charging the cell from a depleted state and the bq34z100 powers up, it could measure a bad OCV on the first cycle. Make sure that the bq34z100 eventually has a way to take an OCV to correct a possible bad initialization.

1) Is this equally true for a host-driven scenario? If yes, then it seems moot.

2) Would a 2nd cycle resolve this? Given that my described scenario is a worst case, it seems a bad OCV on the first cycle is a small price to pay if it is resolved by the 2nd cycle.

David

0 Kang Kang over 5 years ago in reply to David McRell

TI__Mastermind 24870 points

1. Yes.

2. Yes, try to perform a second cycle. Wait for 5 hours to get an OCV measurement after every charge. Wait another 5 hours after every discharge.

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BQ34Z100-G1: datasheet clarification regarding reset