BQ76PL455A-Q1: communication rate and response time questions

HI John,

Here is my respond.

1. Reset is 250K but customer can choose the baud rate. It's customer's choice. There is no recommendation. Both baud rates works. Some MCU can't support 1M and that was the reason to have 250K

2. It's all depends on conversion time and how you convert and read. 1. You can do convert and read the registers or  you can do write with responds. So let me know how you are performing this.

3. fault can detect fault and alert to MCU. This is advantage of having FAULT pins. If not then you have to read fault registers every time. I personally like to use FAULT pin.

4.  It's take about 220uS per device. If you have 3 then it will take about 440uS. This is worst case

5. There is logic analyzer you can find in the web.

6. See the attachment.

Rogerbq76PL455A-Q1 Best sampling set-up.pdf

hi Roger Hwang, appreciate the quick feedback.

can we check with you on some remaining question?

2. It's all depends on conversion time and how you convert and read. 1. You can do convert and read the registers or  you can do write with responds. So let me know how you are performing this.

I want to get the information of all ADC channels. I think the packet like below but with all channels are selected.

3. fault can detect fault and alert to MCU. This is advantage of having FAULT pins. If not then you have to read fault registers every time. I personally like to use FAULT pin.

I just wonder if there is anybody connects the FAULT_N pins of the stack(e.g. 16 packs) to MCU? Or always just use the Fault_N to MCU?

5. There is logic analyzer you can find in the web.

To use logic analyzer, I just can see the waveform and I need to decode by myself, right?  Is there any tool can translate the waveform to hex data for me?

hi Roger, also regarding the "Best Sampling slide"

I think it gets ADC by choosing CMD_OVS_CYCLE=0 which it get cell voltage one by one.

What customer wants to know is that if they choose CMD_OVS_CYCLE=1 which it scans cell 1~16 first and then do 8 times.

The total time for cell 1~16 will be as below or ???

60(ADC_PERIOD_VOL)*16(cell 1~16)*8(oversampling) = 7680us

hi Roger, can we further have your comments on the questions below? Thanks very much

HI John,

I strongly suggest your customer to follow attached PDF.

That is the best.

It has calculation for conversion time as well.

bq76PL455A-Q1 Best sampling set-up.pdf

60(ADC_PERIOD_VOL)+ 7(oversampling) *16

should be (60uS+ (7*12.6us))*16 =2371uS.

roger

hi Roger, 

appreciate the feedback.

from the pdf you showed, it has two routes CMD_OVS_CYCLE = 1 or = 0

the time estimate example should be CMD_OVS_CYCLE = 0 right?

(60uS+ (7*12.6us))*16 =2371uS.

can we check what's the timer estimation with CMD_OVS_CYCLE = 1 ?

it's expected to be more as there will be switch between each channel right? customer would like to know the time estimation with CMD_OVS_CYCLE=1 to evaluate if they can wait that long.

Thanks very much for the help

Hi John,

The time it takes to finish the 8 samples is the same for CMD_OVS_CYCLE = 1 or = 0

Best regards,

Leslie