BQ76940: Booting problem

manish singh18

Part Number: BQ76940
Other Parts Discussed in Thread: BQ76200

I have designed a BMS with BQ76940. It features hihg side curent sensing with BQ76200 and data logging, And i m using Atmega328p.

Problem is i m not being able to power-up the BQ76940 after connecting 15 cells, i.e i cant red any voltage at REGOUT.

Steps followed

1. Connected 15 cells in series

2. pressed boot button.

Did i miss any thing.

Its my first post and i m very hopeful for solution.

Thanks

I have attached the complete schematic.

SCHEMATIC1 Board1-CELL7 4-1-17.pdf SCHEMATIC1 Board1-MCU5 3-13-17.pdf SCHEMATIC1 Board2-MOSFET 1-6-17.pdf

over 8 years ago

0 Vish Nadarajah over 8 years ago

TI__Expert 6085 points

Hi user,

the bq76940 needs an external boot signal ( >1V) on the TS1 pin. The boot sequence is TS1( >1V), CAP1-->REGOUT-->SCLK--> CAP2-->CAP3.

REGOUT should be high to READ I2C.

0 manish singh18 over 8 years ago in reply to Vish Nadarajah

Prodigy 75 points

Hey Vish
I know about condition of TS1 pin to boot IC. I have done that but it did not work.
You have mentioned following in your boot sequence
CAP1-->REGOUT-->SCLK--> CAP2-->CAP3
Pardon me, I did not get it. Could you please elaborate?

0 Vish Nadarajah over 8 years ago in reply to manish singh18

TI__Expert 6085 points

The sequence means, after the WAKE ( >1V on the TS1), the device boots up in this order and completed full-boot-up sequence; d/s spec is Tbootready max 10ms.

0 manish singh18 over 8 years ago in reply to Vish Nadarajah

Prodigy 75 points

Ok. What I understand is, I just have to press boot button(i.e. provide TS1>1V for few milisec, and the sequence you provided is internal process.
If it is so, I have done it. It did it not work.
Will the sequence(you provided) help me diagnose the problem?
Can you also please tell me, how do I confirm if IC is defective (due to whatever reason like misshandling)?

Power management

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BQ76940: Booting problem