6 Replies Latest reply on Apr 17, 2019 5:34 PM by YuMa_1534086

    Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.

    YuMa_1534086

      Hello cypress.

       

       

      Q1)

      CY7C64355 has 2 VDD spec of “VDD” and “VDDUSB(regulator enabled or bypassed)”.

       

      Below is my understanding.

      =====================================================

      If user uses local voltage of their board as encore supply voltage , they need to meet “VDD” spec.

      If user uses VBUS of USB cable as encore supply voltage , they need to meet “VDDUSB” spec.

      =====================================================

       

      How does encore detect if current power source is local voltage or VBUS?

      Or does encore not detect power source kind?

       

      If encore does not detect power source kind, why did cypress divide VDD spec into “VDD” and “VDDUSB”?

      Did “VDDUSB(regulator enabled, 4.35V to 5.25V)” just copy USB VBUS spec?

       

      And “VDDUSB” spec is divided by LDO condition(enabled or disabled).

      Should “VDD” spec also be divided by LDO condition?

      Min “VDD” is 3.0V.

      3.0V is lower than internal LDO output(3.3V).

      Why is “VDD” range from 3V to 5.5V?

       

       

       

       

      Q2)

      In DS, VDD’s conditions is “No USB activity”.

      VDDUSB’s conditions is “USB activity”.

       

      What does the word of “No USB activity” and “USB activity” explain?

       

      Because USB communication should be done even if local voltage is used, I do not understand the meaning “No USB activity” well.

      Is it simply the difference in only power source kind?

       

      Is below idea correct?

      ===================================================

      Cypress just described “No USB activity” as a case of using local voltage as encore supply voltage.

      Cypress just described “USB activity” as a case of using VBUS as encore supply voltage.

      The difference between “No USB activity” and “USB activity” is only the difference of power source kind(local voltage or VUBS).

      ===================================================

       

       

      Best Regarding.

      Yutaka Matsubara

        • 1. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
          HirotakaT_91

          Hi Matsubara-san,

           

          A1)

          >> If user uses local voltage of their board as encore supply voltage , they need to meet “VDD” spec.

          >> If user uses VBUS of USB cable as encore supply voltage , they need to meet “VDDUSB” spec.

          (Wrong comment) Both of them are correct.

          (Correct comment) Supplying Source is not important. enCoRe V does not care whether the voltage comes from VBUS or other power source.

           

          >> If encore does not detect power source kind, why did cypress divide VDD spec into “VDD” and “VDDUSB”?

          >> Did “VDDUSB(regulator enabled, 4.35V to 5.25V)” just copy USB VBUS spec?

          enCoRe V does not detect Power source type on the pin.

          If there are no USB activity (No USB connection), VDD pin range is "VDD".

          If USB activity exists (there is a USB connection), device should comply with USB Spec. VDD pin range is "VDDUSB"

          Hence, these voltage range are different.

           

          >>Should “VDD” spec also be divided by LDO condition?

          (Wrong comment) As per the TRM, a built-in regulator that can be used to power the transceiver from the USB bus voltage or other supply around 5 V.

          Thus, the answer is Yes.

          (Correct comment) If you do not USB communication, you do not need to use a built-in LDO.

          If the device uses USB communication and VDD is around 5V (should comply with 4.35 - 5.25V), you should use the built-in LDO.

           

          >> Why is “VDD” range from 3V to 5.5V?

          VDD range is considered as 3.3V ± 10% tolerance and 5V ± 10% tolerance.

          Anyway, supplying 3.3V or 5V (if you use a built-in regulator) would be a good design.

           

          A2)

          VDDUSB is defined as the VDD supply needed when USB block is used.

          If the customer is not using USB, the chip VDD can be from 3.0 to 5.5V.

          If the customer is using the USB block, they should consider VDDUSB.

           

          Best regards,

          Hirotaka Takayama

          • 2. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
            YuMa_1534086

            高山様

             

            ご回答有難う御座います。

             

            ただ“No USB activity”と“USB activity”の条件の違いが具体的に分かっておりません。

             

            単純にVDD端子に供給するPower Source(ローカル電源 or VBUS)の違いではないという事でしょうか?

             

            Power Sourceが違っていてもUSB通信は行われるので(USBの機能は使われるので)、

            USBのactivityの有り無し(接続のありなし、USB Blockを使う、使わない)で条件分けをされている理由が良く分かっておりません。

             

            USBのactivityとは具体的に何を指しておりますでしょうか?

             

            お手数ですが、どうか宜しくお願い致します。

            • 3. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
              HirotakaT_91

              Hi,

               

              (See below for the Japanese version)

               

              The important thing is that whether the devices carry out the USB communication or not.

              "USB Activity" stands for "USB communication is exist".

              To put it simply, if the device uses USB communication, please follow VDDUSB DC spec whereas if the device does not use USB communication, the device can follow VDD DC spec.

               

               

              USB Activity = USB通信があるかどうか です。

              enCoRe VチップはUSB通信を行わない場合には3V~5.5Vの範囲で動作します。

              USB通信がある場合には、VDDUSBのDC Specに従う必要があります。

              内部レギュレータを使う場合に、入力電圧は4.35V - 5.25Vに従う必要があります。この電圧範囲で入力することで、内部レギュレータから正しく3.3Vが出力されます。

               

              Self-Powered / Bus-Poweredであることは重要ではなく、USB通信があるかどうか(USB Activityの有無)が重要です。

              お客様の環境としてUSB通信を使われているようなので、Self-Poweredデバイスであっても、VDDUSBに従う必要がございます。

               

              最初の投稿も少し編集しましたので併せてご確認ください。

              よろしくお願い致します。

              Hirotaka Takayama

              • 4. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
                YuMa_1534086

                高山様

                 

                ご回答有難う御座います。

                 

                USB Controller ICでUSB blockを使わないケース(No USB activity)とはどのようなケースがありますでしょうか?

                 

                どうか宜しくお願い致します。

                • 5. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
                  HirotakaT_91

                  Hi,

                   

                  (See below for the Japanese version)

                  For example, enCoRe V (CY7C64355) has a bunch of GPIOs and it can work as co-processor by using these GPIOs.

                  Because it is a USB controller IC, Most of the customers use USB feature, though.

                   

                   

                  例えばですが、enCoRe V 多数のGPIOを備えており、これを活用しコプロセッサ等として使うことが可能です。

                  ただ、ご指摘いただいている通り、USB controllerなのでUSB blockを使わないケースはかなり珍しいと思われます。

                  よろしくお願い致します。

                  Hirotaka Takayama

                  • 6. Re: Regarding CY7C64355-48LTXC supply voltage spec of “VDD” and “VDDUSB”.
                    YuMa_1534086

                    高山様

                     

                    ご回答有難う御座います。

                    承知致しました。

                     

                    どうか宜しくお願い致します。