BQ24800: About PMON function

>2. For further assistance with PMON calculations, please refer to the design tool provided below.

bq24800 calculation tools rev2.0.xls

Thank you for your kindness reply.　We checked the above sheet. However,I could not know about I wanted to know.

I would like to understand the mechanism of the PMON correctly.

Below diagram is our understand now. Is it correct ? Please teach it is correct, or incorrect.
If incorrect, please teach the correct mechanism.

Mechanism of our understand now:
When RAC 5mohm/RSR 10mohm, 5mohm occurred voltage is 1/2.
Therefore set 0x3B[13:12]=10b. As the result, RAC side power is doubled by Gain×2 , then RAC side (Adapter) power is added to RSR side (Battery discharge) power.

Best regards.

I'm sorry added question to above PMON mecahism question.

>1. PMON output current will not exceed the maximum output current rating of 100uA.

If condition is RAC:5mohm/RSR 10mohm and max 400W = 0.25uA/W (Reg0x3B[9]=0, REG0x3B[13:12]=10b), if current consumption is flowed over 400W or more, for example 500W, etc, What is happen? PMON function is still keep 100uA? We are worrying IC broken, PMON output abnormal, etc.  

Best regards,

Thank you for youre reply. We contact TI Japan.

We have other questions.

(6). If PMON port is set to floating, PMON voltage will be very high? or PMON will be around 0V? 

(7). Even If PMON port is shorted, current consumption from PMON is only 100A as maximum?
       Or high current consumption is drained from PMON port? Then PMON port will be broken?

(8).  

      >In the datasheet, the system power monitor accuracy (PMON) has a value of +/-5%, this is the value used for Hybrid boost mode.

When the Adapter Only 19.5V/45W accuracy +4% & Battery Only 11V/44W accuracy +4.5%, calculation of total accuracy is +4.3% by below.

(45W×1.04 +  44W×1.045) / (45W+44W) = 104.3%

Is 5% of your answer rounded integer value？
Or other cause? Could you tach it, please?

We are think that we will use this functuon, therefor, we would like to confirm it. 

Today is a US holiday, please check it back after Tuesday.

I'm sorry for additional question. We would like to use the following information to check the PMON spec is meet to our system.

<About Input power>

(1). When condition is APMON 0.25uA/W and PMON output 100uA max, PMON is able to output 400W.

      In this condition, Can we input the power to 400W or more to charger?

      Our system power may be exceeded 400W for a short moment.( e.g. 500W)

<About PMON Accuracy>

(2). When system power source is an AC Adapter only,

     PMON accuracy is difference between light load and heavy load? 

 If PMON accuracy of between light load and heavy load is not same,  (when power source is AC Adapter only)

 Please send the accuracy data of 20V AC adapter about light load and heavy load.

 (Data of Accuracy(condition Adapter 20V) vs load)

(3)  When system power source is an Battery only,

     PMON accuracy is difference between light load and heavy load? 

    If PMON accuracy of between light load and heavy load is not same,  'when power source is Battery only)

    Please send the accuracy data of 13V and 15V and 17V  of Battery voltage about light load and heavy load.

    (Data of Accuracy(Battery 13V/15V/17V) vs load)

(4). When AC adapter 230W, and mode is Hybrid boost mode,  and battery load 50W/100W/150W,

       Could you teach the PMON accuracy each condition(a) (b) (c)?

(a). AC adapter 230W + Battery 50W.

(b). AC adapter 230W + Battery 100W.

(c). AC adapter 230W + Battery 150W.

Hello Norimichi,

Please allow some time for further research on your questions. I will update you by Tuesday.

Sincerely,

Adriana Gonzalez Vega

Thank you for your reply. We look forward to get your informations about above (1)-(4).

Besides, could you teach the below additional question?

・Please teach the accuracy of PMON Output Current.

Thank you for your reply and help.

>1. The max 100uA/3.3V spec is not allowed to exceed for a short or long moment. 

(1). Even if System load is exceeded from PMON max range, Is PMON output crampted 100uA as max as below diagram, is it correct ?

>4. As per the hybrid boost mode equation denoted above, you can estimate the values below. It is within the 5% heavy load range. 

(2). When condition is RAC 5mohm and RSR 10mohm, accuracy is changed? or same?

For example, Adapter 45W is 4% at RAC 10mohm, but when 5mohm, RAC voltage is divided 1/2 from 10mohm.
In this case, we must be think that it acuuracy is same as 22.5W condition nealy 24W 6%?

Or if gain is set correctly by REG0x3B[13:12]=10b(RAC 5mohm/RSR10 mohm), we can think that same as 45W 4% of RAC 10mohm even though actual RAC is 5mohm?

Which is correct?

>5. PMON output current accuracy is not specified in the datasheet, we do not have a spec/tolerance for this parameter.

(3). We would like to check that which is correct below A or B.

A. PMON output has posibility that is exceeded 100uA by plus accuracy. eg. 102uA by plus accuracy 2%.

B. PMON output is 100uA max even if PMON output has plus accuracy.

We will use above information to care for PMON connecred device.

Best regards,

Thank you for your help.

I'm sorry 

>1. Correct, PMON output current cannot exceed 100uA.

As below diagram, the our system load is exceeded 400W little moment(e.g. 500W), Is it no problem to the charger?
We would like to confirm that charger is no problem at the below diagram condition just to make sure.

Of course, we will keep to the pin recommended voltage specifications(SRN/SRP and ACN/ACP) as a precondition.

(And also, PMON output 100uA max clamp behavior when PMON max is exceeded is good for our system.)

Best regards

I'm sorry, we have the question about below Q&A.

>Our Question.

>(3). We would like to check that which is correct below A or B.

>A. PMON output has posibility that is exceeded 100uA by plus accuracy. eg. 102uA by plus accuracy 2%.

>B. PMON output is 100uA max even if PMON output has plus accuracy.

>Your Answer

>3. Statement B is correct, PMON output is 100uA max, it cannot exceed this value.

When below diagram condition, if 0.25uA/W max 400W, typical ouput current is 100uA normally.

But, even if clampted 100uA, we think that the actual output current maybe 100uA + xx% by accuracy by hardware acuuracy etc as the below Diagram No.1.

[Diagram No.1]

If keep the max100uA perfectly even if hardware has tolerance, we think that the typical value must be subtracted the amount of tolerance as the below diagram No.2.

[Diagram No.2]

What is the correct? Is Diagram No.1 or No.2 correct? Or other is correct?

If correct answer is not Diagram 1 or 2, Could you explain this reason, please?  

Best regards,

Thank you for your reply.

＞The 100uA maximum still stands, if there is any hardware tolerance, Diagram 2 would be applicable. The device will not allow a value greater than 100uA ＞+ tolerance. 

Could you teach the PMON output actual tolerance of charger, please? We must to know Diagram 2's actual typical value because we will use this function. 

Best regards,

Hello Norimichi,

Could you please give more information on the application of this tolerance? Typically, given the spec of 100uA maximum output current for PMON output will allow you to use the PMON function. 

Sincerely,

Adriana Gonzalez Vega 

Thank you for your reply.

Our system image is below.

APMON 0.25uA/W. When System load 400W, PMON output must be within 100uA +/- 5% on our system.
Therefore, If PMON output will not allow a value greater than 100uA, We need to spec must be within 100uA -5%.

For example, Our system can't allow the below case's tolerance because Min value is -10%.

Therefore, we need to know value that the below diagram's  "① typical." and "② Min" by based on an actual tolerance, If PMON output will not allow a value greater than 100uA.

Best regards,

Hello Norimichi,

Thank you for your patience. I will update you on your request by end of business Wednesday

Sincerely,

Adriana Gonzalez Vega

Thank you for your reply. I added the red rescription. I'm sorry.

>Therefore, we need to know value that the below diagram's  "① typical." and "② Min" at 400W @APMON 0.25uA/W by >based on an actual tolerance, If PMON output will not allow a value greater than 100uA.

----

Our system image is below.

APMON 0.25uA/W. When System load 400W, PMON output must be within 100uA +/- 5% on our system.
Therefore, If PMON output will not allow a value greater than 100uA, We need to spec must be within 100uA -5%.

For example, Our system can't allow the below case's tolerance because Min value is -10%.

Therefore, we need to know value that the below diagram's  "① typical." and "② Min" at 400W @APMON 0.25uA/W by based on an actual tolerance, If PMON output will not allow a value greater than 100uA.

Best regards,

Thank you for your reply.

1. Could you teach the "PMON clamping current"'s accuracy?
    We must to know that PMON is clamped value of most minimum case.(For example 98uA, etc)

2. Is "PMON accuracy" as below as old your mail? Is it correct?

a. (230W×1.04 + 50W×1.045) / (230W+50W) = 104.197%

b. (230W×1.04 + 100W×1.045) / (230W+100W) = 104.151%

c. (230W×1.04 + 150W×1.045) / (230W+150W) = 104.089%

3. Our system's RAC sense resistor's accuracy is +/-1%.
  Besides, RSR sense resistor's accuracy is +/-1%.
  About the "total PMON accuracy", is it still No.2 question's value? (230W×1.04 + 50W×1.045) / (230W+50W) = 104.197%…
Or should we think more big accuracy from No.2 question's value?
If we should think more big accuracy, could you teach the calculating formula, please?
We must to set when 200W or more PMON accuracy within 5%.

Best regards,

Hello Norimichi,

As stated, the PMON clamping current is 100uA with no tolerance. 

The PMON accuracy calculations stated earlier are correct.

We are working to develop the calculations for total accuracy. Though to mention, small tolerances are already taken into account, if you are using a resistor with high tolerance value, it will need further calculation efforts.

If you have any new requests or questions that differ from the original thread, we do ask that you create a new thread for better readability, thank you.

Sincerely,

Adriana Gonzalez Vega

>We are working to develop the calculations for total accuracy. Though to mention, small tolerances are already taken into >account

Thank you for your reply

+/-1% tolerance resistor is same as EVM board. Is it already taken into account? Is it correct?

Best regards,

Hello Norimichi,

Thank you for your patience, we will get back to you with updates early next week. 

Sincerely,

Adriana Gonzalez Vega

Hello Norimichi, 

Could you add further clarification as to why a resistor with high tolerance is used, we recommend using a low tolerance resistor as it is already taken into account in the accuracy specified in the datasheet. 

Sincerely,

Adriana Gonzalez Vega

Thank you for your reply.

>why a resistor with high tolerance is used

1% tolerance RAC and RSR current sense resistor is most low tolerance resistor as the below url normally.

Welcome to Cyntec - Current Sensing Resistor]

TI BQ24800 EMI board's RAC and RSR current sense resistor is also 1% tolerance.
Therefore, we will use the RAC and RSR current sense resistor as most low tolerance 1%.

On above condition of RAC/RSR tolerance 1%,
Is "PMON accuracy" as below? Is it correct ?
a. (230W×1.04 + 50W×1.045) / (230W+50W) = 104.197%
b. (230W×1.04 + 100W×1.045) / (230W+100W) = 104.151%
c. (230W×1.04 + 150W×1.045) / (230W+150W) = 104.089%

Best regards,