14 Replies Latest reply on Nov 29, 2019 10:46 PM by JHch_4126036

    CX3 PMODE Level

    JHch_4126036
      • device : CYUSB3064.
      • IO voltag 3.3V
      • PMODE[2:0]:0F1
      • CX3 internal Pull-up 50KΩ. Internal Pull-down 10KΩ.

       

      • Cypress reommends:

      • Electrical Charateristic

             VIH : 1.4V , VIL : 0.45V

       

      • Figure1.

       

      Figure1_10K-PU_10K-PD.png

      • Figure2.

           Figure2_1K-PU_GND.png

      • Question

                1. In Figure1, PMODE0 drops to 1.2V.

                      1.2V is lower than VIH(1.4V).

                      Is this OK?

                2. In Figure2, PMODE0 drops to 1.7V.

                       This is higher than VIH.

                       For stable status, should I use 1Kohm Pull-up(PMODE0)/ 0ohm Pull-down(PMODE2) ?

       

      jaehyuk choi 님이 메시지를 편집했습니다.

        • 1. Re: CX3 PMODE Level
          JayakrishnaT_76

          Hello,

           

          Please confirm whether you are asking about PMODE 1 or not because i cant find a pull up resistor on PMODE 1.

           

          Best Regards,

          Jayakrishna

          • 2. Re: CX3 PMODE Level
            JHch_4126036

            Hi,

            Sorry for a typing error.

            I changed PMODE1 to PMODE0.

             

            thanks,

             

            Choi.

            • 3. Re: CX3 PMODE Level
              JayakrishnaT_76

              Hello,

               

              Please let me know all the power domain voltages that you are using in your schematic?

               

              Best Regards,

              Jayakrishna

              • 4. Re: CX3 PMODE Level
                JHch_4126036

                Hi Jayakrishna

                 

                 

                1.2V : VDD. U3RXVDDQ. U4TXVDDQ. CVDDQ. AVDD.

                1.8V : VDDIO1. VDDIO2. CVDDQ.

                3.3V : VDDIO3.

                5V : VBUS.

                 

                Thanks,

                Choi.

                • 5. Re: CX3 PMODE Level
                  JayakrishnaT_76

                  Hello,

                   

                  I used the same Power Domain voltages as yours on the Denebola kit. I found that the PMODE lines were at 1.8V itself when they were pulled up externally to 1.8V using 10k resistor.

                  Please make sure that your LDO outputs 1.8V correctly without connecting it to CX3. Also please let me know if you have connected any other component to PMODE0 pin.

                   

                  Best Regards,

                  Jayakrishna

                  • 6. Re: CX3 PMODE Level
                    JHch_4126036

                    Hi,

                     

                    LDO outputs 1.8V without connecting to CX3.

                    PMOD0 has only a 10Kohm pull-up.

                     

                    [Figure1]

                    CX3 seems to be working, to see if the PMODE is High, Low, or Hi-Z.

                    When CX3 checks 'High', the level of PMODE2 is 0.25V.

                    When CX3 checks 'Low', PMOD0 is 1.2V.

                    This is a possible results, when the CX3 uses 50Kohm/Pull-up and 10Kohm Pull-down.

                    Caculation, 10Kohm / (10Kohm + 10Kohm) x 1.8V = 0.9V. 10Kohm / ( 50Kohm + 10Kohm) x 1.8V = 0.3V

                    Would you agree with this ?

                     

                    VIH min of CX3 is 1.4V, VIL max of this is 0.45V.

                    When CX3 check low, PMODE0 drops to 1.2V.

                    Doesn't it matter because 1.2V is higher than 0.45V ?

                    Or is it matter because 1.2V is less than 1.4V ?

                     

                    Best Regards,

                     

                    Choi.

                    • 7. Re: CX3 PMODE Level
                      JayakrishnaT_76

                      Hello,

                       

                      Please let me know the following:

                      1. Are you facing any issue with enumeration? Also is the board working when you are using 10k Pull up resistor?

                      2. Also, is that 0.25V spike and 1.2V dip which I see in fig 1 a glitch? Or is it staying at this level for a prolonged time?

                       

                      Best Regards,

                      Jayakrishna

                      • 8. Re: CX3 PMODE Level
                        JHch_4126036

                        1. Are you facing any issue with enumeration? Also is the board working when you are using 10k Pull up resistor?

                             => When I are using 10K Pull-up resistor, it operats normally.

                                  But, we are going to mass production.

                                  Thus, it has not been berified in mass product yet.

                                  Before mass production, I wnat to make this status.

                                  I want to make the board stable and reduce the problem of M.P.

                                  

                        2. Also, is that 0.25V spike and 1.2V dip which I see in fig 1 a glitch? Or is it staying at this level for a prolonged time?

                             ==> 0.25V and 1.2V occur once at 480us after reset. ( refet to figure1).

                                    So, I guess it is normal boot step for CX3.

                                     Please tell me the stable boot condition.

                        thanks,

                         

                        Choi

                        • 9. Re: CX3 PMODE Level
                          JayakrishnaT_76

                          Hello,

                           

                          Can you please measure the ramp up time of 1.8V LDO and let me know the result?

                           

                          Best Regards,

                          Jayakrishna

                          • 10. Re: CX3 PMODE Level
                            JHch_4126036

                            Hello,

                             

                            5.0V -> 0.4msec -> 1.2V -> 0.47msec -> 1.8V -> 3.8msec -> 3.3V -> 3.4msec -> RESET#

                             

                             

                            thanks,

                             

                            Choi.

                            • 11. Re: CX3 PMODE Level
                              JayakrishnaT_76

                              Hello,

                               

                              Please send me a consolidated waveform having Reset, Power rails and PMODE. We need to compare every waveform with reset.

                               

                              Best Regards,

                              Jayakrishna

                              • 12. Re: CX3 PMODE Level
                                JHch_4126036

                                Hi, Jayakrishna

                                 

                                I attached the signal you want.

                                Thanks for you to reviewing the whole circuit.

                                I want to confirm the first question.

                                Is level drop of PMODE0 and level up of PMODE2 normal state? (Of course, CX3 woks fine. I just want to complement our system)

                                Is PMODE0 normal state with 1.2V in initial state?

                                If so, give me min value of PMODE0 and max value of PMODE2 in the initial state.

                                 

                                Best Regards,

                                 

                                Choi.

                                 

                                 

                                P

                                • 13. Re: CX3 PMODE Level
                                  JayakrishnaT_76

                                  Hello,

                                   

                                  The dip and spike that you see are expected. After Reset, we enable a weak pull up followed by pull down internally in the PMODE pins to check whether the PMODE Pin is in High-Z, High or Low state. Initially, a weak pull up is enabled and we wait for about 6us during which the state of the pin is sampled. Then we enable a pull down and wait for 6us.

                                  Because of this, you find a 0.25V spike first for 6us and then a dip to 1.2V for 6us. This is an expected behaviour. This will not affect the functionality.

                                   

                                  Best Regards,

                                  Jayakrishna

                                  • 14. Re: CX3 PMODE Level
                                    JHch_4126036

                                    Hello,

                                     

                                    Thank you for your answer.

                                     

                                    Best Regards,

                                     

                                    Choi.