Hi
If Ct is connected to VDD directly, how does TPS3808G50 behave?
is there possibility to damage the device?
BestRegards
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Hi Michael
Thank you for your answer.
Sorry, I shall inform the IC name correctly. It is TPS3808G50-Q1.
For FMEA, my customer wants to confirm the behavior when CT pin is shorted to VDD directly.
Could you please tell me why the resistor is needed between VDD and CT pin?
Isn't it the current limit?
I would take the external circuit to avoid damaging device if shorting CT and VDD leads to device damage.
BestRegards
Hi Michael
Let me explain the problem case more detail, and please check.
Normally, the device works like the following left figure.
And the situation we should avoid is the right one.
As workaround, we are considering inserting resistor like as the following.
We believe that the device won't be damaged if assuming short factor using this way.
However, it will connect 40Kohm-200Kohm resistor between SENSE and VDD.
Do you think there is any bad effect for SENSE monitoring by inserting resistor like this?
BestRegards
That will not work. Please use a configuration shown below:
Notice that CT isn't directly connected to VDD or SENSE in any of the configurations. CT only has 3 possible configurations as shown above. The SENSE pin can't be directly connected to CT because the SENSE is monitoring the voltage on that pin and will trigger reset if the voltage drops below Vit but CT is being charged and discharged to create the internal delay for the reset delay timing.
Why can't you use configuration (a)?
-Michael
Hi Michael
Thank you for your reply.
>Why can't you use configuration (a)?
Now, VDD pin and SENSE pin are connected to VDD.
So, I think short between CT and VDD is unavoidable if short factor is assumed, even if we use configuration (a).
That's why customer’s idea is to use (I) configuration (following figure).
The customer wants to avoid device damage.
So I want to ask you if the system would work in (I) configuration, without impact.
(II) is the unusual situation when problem occurs.
Of course, I think it won’t work well when (II) condition.
However, I think the device will avoid the situation of damaging device in short condition
of CT and SENSE (CT and VDD in otherwords).
BestRegards