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BQ78350-R1: AOLD delay

Part Number: BQ78350-R1

Hello;

I'm unclear about the explanation and actual operation of the the 76920's AOLD (and ASCD) protections, vs. that of the explanation in the  78350 TRM.

As per 10.3.1.2.1 in the 920 datasheet,  the programmable delay for the HW protection OCD (= 78350's AOLD) is limited to 8 discrete periods, from 8ms to 1280ms: 

But the 78350 TRM lists a range of delays and counters that far exceed those of the 920? 

I don't understand how the 78350 can implement these delays.  But I want to delay opening the discharge fet for 30 seconds during an AOLD event...But unless I'm misunderstanding, it seems that the 920 will disable the fet in no later than 1280ms?? Does this mean that it actually would in this case, but that the 78350 immediately turns it back on?

Protections AOLD Threshold and Delay H1 0x00 0xFF 0x00  <- this appears to correspond to the 920's  PROTECT2 register
Protections AOLD Latch Limit                 U1 0       255   0 counts
Protections AOLD Counter Dec Delay    U1 0       255   10 s   <- ??
Protections AOLD Recovery                   U1 0       255   5 s     <- ??
Protections AOLD Reset                         U1 0       255   15 s   <- ??

Signed Confused;

  • Hi Jeffrey,

    The Protections AOLD Threshold and Delay parameter is written into the BQ769x0's register to control the threshold and delay of the overcurrent.  

    For recovery the BQ78350-R1 determines when to recovery.  It has a general recovery on time delay, and if that re-occurs it will latch and recover from the latch on a different delay.  See the table in the TRM section 3.6.1.  I think the recovery and latch rows should have been swapped, but the author chose the layout.

    However there are other recovery options, pack removal and in some situations load removal, see the appropriate sections of the TRM.

  • Understood;

    I was hoping I there were means of delaying FET opening during an overload for 30 seconds, but I see now that only the recovery can be delayed.

    Thanks