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TPS3703-Q1: recomended reset IC with +-4.7% tolerance window

Part Number: TPS3703-Q1
Other Parts Discussed in Thread: TPS3703,

Hi team,

Could you help recommended the high accuacy voltage detection reset IC?

The TPS3703 would be a perfect solution for the application, but the voltage need to be monitor is 1.26V(typical)

The customer need the voltage not exceed +-4.76%(tolerance window), is there any recomended solution?

1.26

 

1.2

 

-4.76%

 

 

1.32

 

4.76%

Best regards.

  • Hi Fanbin,

    Thanks for reaching out about this. The part number for the thread states the TPS3703-Q1, but your description states the industrial-rated TPS3703. Does the costumer need an automotive-qualified part?

    Unfortunately, we don't have any automotive devices that exactly fit the costumer's requirements. If they need an automotive-qualified part, would they consider using external resistor dividers?

    Thanks,

    Patrick

  • Hi Patrick,

    Yes, we need an automotive part, what is the recommended part number to achieve this feature with external resistor?

  • Hi Fanbin,

    We recommend using the 0.8V threshold option of the TPS3703-Q1 because it doesn't have an internal resistor latter.

    Thus, the two available options would be:

    TPS3703B3080DSERQ1 - 3% threshold window, 0.8V nominal voltage (adjustable), reset delay capacitor-programmable (CT pin open 1ms, tied to VDD 20ms)

    TPS3703E4080DSERQ1 - 4% threshold window, 0.8V nominal voltage (adjustable), UV-only reset delay capacitor-programmable (CT pin open 10ms, tied to VDD 200ms).

    Please see section 9.1.4 in the data sheet for additional information on using the TPS3703 in an adjustable fashion.

    Thanks,
    Patrick

  • Hi Patrick,

    Thanks for your suggestion.

    But I'm not sure if the exyernal resistor divider solution would work, because i check the functional block diagram, there is resistor divider inside the Sense pin, can we still put a external resistor here, i guess there would be some mismatch because similar resistance.

    and I don't understand what is "We recommend using the 0.8V threshold option of the TPS3703-Q1 because it doesn't have an internal resistor latter."mean?

    is there no internal resistor inside? can you show me the block diagram for the part number you showed me?

  • Hey Fanbin,

    Attached is a description of my comment, taken from section 9.1.4 of the data sheet. The internal resistor divider normalizes an external voltage on devices with thresholds above 0.8V. When using the 0.8V threshold variant, there is no need for normalizing to a 0.8V threshold inside the device, and thus that process can be done externally. The block diagram for the 0.8V threshold variant is identical to the ones on the data sheet except for the absence of the internal resistor divider.

    Thanks,

    Patrick

  • Hi Patrick,

    First, for the 0.8V threshold version, what does the internal resistor look like? what is the "bypass mode of the internal resistor ladder" means? can you should me a picture to illustrate?

    from the datasheet, we need to well consider the external resistor and Rsense to calculated the total error. what is the inside Rsense? Is it the same as what the "bypass mode of the internal resistor ladder" means? If so the customer need to know the value and the resistance error for the Rsense? Why the customer need to use the equation to calculate the Rsense by themselves, would it be a different value for different Vmon and external divider? 

    given current solution, how can the customer calculate the total error of this circuit?

  • Hi Fanbin,

    The TPS3703-Q1 has an internal 0.8V reference that it compares the SENSE voltage with. On fixed variants, the normalization is done by an internal resistor ladder. However, no normalization is necessary on the 0.8V because 0.8V is the targeted measuring voltage, and thus no internal resistor ladder is present during operation.

    The costumer will only need to consider error from external resistors on top of the 0.7% maximum error.

    Thanks,

    Patrick

  • Hi Patrick,

    I didn't understand"no normalization is necessary on the 0.8V because 0.8V is the targeted measuring voltage, and thus no internal resistor ladder is present during operation", can you help provide a block diagram to show me? But what is the discription below means, why we add this in the datasheet?

    Are you avialable for a webex meeting on this issue?

  • Hi Fanbin,

    As we will discuss this more in a call, I will close this thread. Please mark it as "Resolved" if you feel this topic was addressed properly.

    Thank you,

    Patrick