BQ4050: To Enable PROCHOT Assertion

Hi Arpan,

Can you please confirm that this is for the bq4050 device? I believe register 0x21 for bq4050 is DeviceName().

Regards,

Anthony Baldino

Hi Anthony,
My mistake, this is for bq25720 (Battery Charger). Can you now suggest, the setting to do for Prochot assertion.

Hi Arpan,

I have looped in someone from our chargers team to take a look at this.

Regards,

Anthony Baldino

Hi Tiger,

Thanks for your response.

Are we saying charger is working as expected on the basis of changed value of PROCHOT_STATUS 0x21 during Reboot ?

And can you please tell us one more thing, As We want to assert PROCHOT at 8Volt and we are writing 0xE04C in REG0x36 to make it happen. then why it is not asserting at 8 Volt instead it asserts at 5.6V.

Thanks 
Yash

Hi, Yash,

PROCHOT is used for monitoring purpose. To maintain VSYS during transient, we would need to enable peak power mode for example. 

Regards,

Tiger

Hi Tiger,

Thanks for your response. we will enable PEAK_POWER_MODE to maintain VSYS.

But my only doubt here is why prochot is asserting at 5.6 Volt instead of 8 Volt as per the settings ? 

Why do you want to set SYS_UVP=8V? Many set this as low as 2.4V. 

Regards,

Tiger

Hi Tiger,

as our VSYS_MIN minimum system voltage is 9.2 Volt so we want to assert PROCHOT at 8 Volt. that is why we want to set SYS_UVP at 8 Volt.

Hi, Yash,

PROCHOT is triggered on VSYS_TH2, not SYS_UVP. 

Regards,

Tiger

Hi Tiger, 

We have enable the peak power mode on REG0x31, with the Register setting as

min_vsys  (0x3E) = 0x5C00; //--9200 mVolt

iin_host (0x3F) = 0x7800

charge_option0  (0x12) = 0xE70E

/*---------------Prochot Setting-------------------*/

charge_option2 = 0x1037; //12th bit (EN_PKPWR_VSYS):-  Enable peak power mode triggered by system voltage under-shoot , 7th bit (EN_EXTILIM):- Set to 0, Input current limit is set by IIN_DPM register.

charge_option1 (0x30) = 0x3300;

prochot_option0 (0x33)= 0x0981;

prochot_option1 (0x34) = 0x41BF;

charge_option4 (0x36) = 0x0048;

vap = 0x00F0;

Observation:-  We are able to see multiple times, triggering on Prochot signal from 3.3V to 2.6V. But the system booted successfully.
But if we change min_vsys  (REG_0x3E) to 11400 mV (0x7200), then we cant see any triggering on Prochot. and System Booted sucessfully.

Query:- Is this setting good for future to work system on heavy load.
When REG0x3E is set to 9200V, the trigger of Prochot is not proper. It varies from 2.6V to 3.3V, adding image for your reference.

Hi Tiger,

We also dont know why the prochot is getting triggered at 2.6 V,

May be because of this REG0x30 = 0x3300 (7th Bit (CMP_REF), set for 2.3V) 

or REG0x33 = 0x0981 (8th bit (PROCHOT_VINDPM_ 80_90), set for 91% of VinDPM threshold).

Please confirm, if its trigger because of this any register or there is some other reason ? 

2. And this is the captured waveform of VBATA and Prochot signal, where our system gets restart, during shutdown. (when, setting Vsys_min Register to 11.4V).
Why this Prochot assertion is not properly pull down, it seems to be down stair case when VBata gets triggered to around 5.6 V.

Hi Arpan,

I don't know what triggered the PROCHOT. You may need to enable PROCHOT one by one and figure it out the trigger. 

Regards,

Tiger