BQ21040EVM-777: About TS voltage

Hi Teritama,

I will get back to you by the end of the week about this.

Best,
Mira

Hi Mira,

Is there some update about this question?

Best regards,

teritama

Hi Teritama,

Apologies for the delayed response.

I was able to recreate what the EVM User's Guide says using the settings you have provided.

What is the resistance value of R7 that you are reading?

And can you please also try using a different EVM to ensure that this is recreatable in other boards?

Best,

Mira

Hi Mira,

Thank you for reply.

>What is the resistance value of R7 that you are reading?
⇒This phenomenon occurred when customer adjusted R7 min to max resistance. I think the value range of R7 is 500ohm(50k*1%) to 50kohm from 3266W-1-503LF datasheet. Is it same your EVM?  And should we measure R7 resistance between TP6 and GND?

I want to know R7 resistance on your setting condition to know what value is correct.

>And can you please also try using a different EVM to ensure that this is recreatable in other boards?
⇒We don't have the EVM now. This phenomenon occurred on the EVM witch customer have. So first I'll check the resistance to customer. Is this okey?

Best regards,

teritama

Hi Teritama,

Yes, it should be measured across TP6 and GND when Vin is not being supplied.

The lowest R7 resistance on my EVM is 1k ohms and the highest R7 resistance is 50k Ohms for us.
At 1k ohms, Vts is 31mV, and at 50k ohms, Vts is 1.47V.

And okay.

Best,
Mira

Hi Mira,

The customer measured R7, the lowest resistance is 1kohm and highest resistance is 49.85kohm. This result near to your result.   

And Vts is 0.61mV to 0.298V. Vts don't increase to 1.47V.

Best regards,

teritama

Hi Teritama,

teritama said:

And Vts is 0.61mV to 0.298V. Vts don't increase to 1.47V.

Are the Vts values on another board or from the original board?

If from the original board, can you please have the customer try using a different EVM to ensure that this is recreatable in other boards?

Best,
Mira

Hi Mira,

This Vts value is original board. And the customer bought just one. So to use another boards we have to ask the customer to buy second board.

Is it possible that this issue caused by device  damage or the capacitor c5 problem?

Best regards,

teritama

Hi Teritama,

It is definitely a strong possibility that this issue is caused by a damaged device.  I'm unsure if a damaged capacitor, c5 in particular, would cause this behavior.  Does the customer think that it might be a c5 problem?

Best,
Mira

Hi Mira

> Does the customer think that it might be a c5 problem?

⇒No this is just I thought. I think if  R7 is no problem, the issue is caused by device damage or C5. Does this seem likely?

Best regards,

teritama

Hi Teritama,

Apologies for the delayed response.

It is likely that it is a device damage issue.  We do recommend having the customer attempt to recreate the original scenario on a new device, which can be ordered for free through tisamples.ti.com.

Please let me know if the customer is able to recreate the original scenario

Best,
Mira

Hi Mira,

Thank you for your supports.

The customer changed another chip, hits issue isn't be occurred.

Additionally, when we observed this issue Vts was max 0.298V, but TS function followed on datasheet(when R7 adjusted Above 45°C or below 0°C, the charge disabled).

Do you know like this case?

Best regards,

teritama

Hi Mira,

I understood this issue is caused by device damage. We thought this damage is from ESD. So we plan to implement a ESD protection.

Do you have any use case of BQ21040 with TS protection or do you know the case like TS pin damaged by ESD?

Best regards,

teritama

Hi Teritama,

Can you please explain what you mean by "use case of BQ21040 with TS protection"?

Technically, ESD can damage any section/pins of the device, including the TS pin.

Best,
Mira

Hi Mira,

Sorry for my lack of my explain.

I want to some information about the case of using ESD protection on this device ex. countermeasure example, schematic, reference design etc. if you have related information.

>Technically, ESD can damage any section/pins of the device, including the TS pin.

⇒I'll introduce TI ESD protection device ESD321DPY for customer.

Best regards,

teritama

Hi Mira,

The customer is wondering the TS pin is prone to be damaged by ESD in no ESD protection status. The device is damaged when they ware probing to measure.

They plan to use ESD protection on TS pin. However, they concerned if this device's TS pin is sensitive to ESD especially.

Does this issue occur in other customer? If you have some case information we want to know.

Best regards,

teritama

I'll check and get back to you tomorrow, teritama.

Hi Mira,

I apologize to late reply. After the customer use ESD protect device, this issue becomes not occur.

It appears that this problem was occurred from the customer's evaluation environment.

Thank you so much for your kindly supports.

teritama