3 Replies Latest reply on Dec 3, 2018 7:52 PM by SrinathS_16

    CY7C65642-28LTXCT   POR回路について

    NoAr_1540581

      PowerONRESETで使用する(外部よりRESET入力しない)とき、RESET端子(17pin)を内蔵電源の3.3V(Vreg)でプルアップ

      して使用する予定です。添付回路図の右側の構成で問題無いでしょうか?改善点あれば教えて頂けますでしょうか?

       

      マクニカ/荒井

        • 1. Re: CY7C65642-28LTXCT   POR回路について
          SrinathS_16

          Hello Arai-san,

           

          - When resistor R2 is not used:

               In this case, when the VBUS supply voltage is removed, the voltage across the capacitor takes a longer time to discharge itself. During this period, if the VBUS is applied again, there is no RESET pulse on the pin. This means that the external reset is released before the hub's internal reset which is not recommended.

           

          - When resistor R2 is used:

               In this case, when the VBUS supply voltage is removed, the voltage across the capacitor discharges through the resistor R2. Hence, when the VBUS is re-applied, the reset pulse gets applied on the RESET pin. This is the reason behind having a resistor R2.

           

          Best regards,

          Srinath S

          • 2. Re: CY7C65642-28LTXCT   POR回路について
            NoAr_1540581

            Hello Srinath san

             

            Regarding the circuit diagram I attached before. Although it is described as R2 in the answer, this is the understanding of R43, is it correct?

             

            Best Regards,

            Arai

            • 3. Re: CY7C65642-28LTXCT   POR回路について
              SrinathS_16

              Hello Arai-san,

               

              Apologies for the confusion. I was referring the explanation to the below diagram that comes with the CY7C65642 datasheet.

              So, as you have mentioned, R2 corresponds to R43 in your schematic.

               

              Best regards,

              Srinath S