• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 63 subscribers
  • Views 1713 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ76930: VC5B & VC5x

Akilan G
Intellectual 285 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ76940

Hello Sir,

I am new to BQ76930 AFE and I am going through the datasheet, still I din't get few things, which are 

1) Why only TS2 in Bq76930 AFE is having negative terminal as Vc5x and TS1 is grounded normally ?

2) How the VC5B is acting as negative terminal of the 6th cell in the AFE Bq76930 ?

3) Why VC5x is connected to Vc5b ? 

It  would be great if anyone could clear my doubts 

Thanks :) 

  • 0
    TI__Expert 6085 points

    TS1 is referenced to GND. TS2 is referred to the VC5X.  VC5X is the power for the lower group and also reference to the upper group. Likewise, if using the bq76940, then, VC10X would be the reference for TS3.  TS2 is defined as an input and should NOT be pulled up.

    VC5B is the 'input' low reference for cell 6. Its the VC0 for the upper group.

    VC5X is one diode voltage ( ~0.3V) higher than VC5. The diode typically turn ON only at power ON.

    Also BAT comes up slower than VC5X. 

    hope this helps you out.

  • 0 in reply to Vish Nadarajah
    Intellectual 285 points

    Thank you so much. And can you tell me about the Cap 1 and Cap 2 for ? And I was checking the schematics and the cad file, found out that only cap 1 grounded with a cap in lower side isolated ground. what happens if the cap 1 is grounded with both lower and higher side ground ? 

  • 0 in reply to Akilan G
    TI__Expert 6085 points

    CAP1, CAP2, CAP3 are output capacitance for the 3.3V internal LDO for each of the group(bottom/middle/top group). CAP1 is referred to the GND, CAP2 is referred to VC5X; CAP3 is referred to VC10X.... If any of the CAP1 are shorted, the device will malfunction. The part will  go into  SHUTDOWN depending on the duration of the short. Also, if CAP1 is dead shorted to GND, the device will also not have a clean boot. During the wake sequence, (WAK(TS1 >1V) -->CAP1-REGOUT->SCLK-CAP2--CAP3 before the XREADY released. 

    hope this helps you out.

    thanks

  • 0 in reply to Vish Nadarajah
    Intellectual 285 points
    Okay understood that if I connect the cap1 directly to low power ground instead grounding through a 1 micro farad capacitor, the device will not have clean boot. If my above statement is right and clear, my question is , Can the cap 1 be grounded in low power ground and high power ground as well through 1 micro farad capacitor ?
  • 0 in reply to Akilan G
    TI__Expert 6085 points
    use the recommended the CAP1, CAP2, CAP3 sizes per spec. CAP1 will connect to the low power ground.
  • 0 in reply to Vish Nadarajah
    Intellectual 285 points
    Alright, Thanks !