5 Replies Latest reply on Dec 18, 2018 10:40 PM by prbd

    [FM24V02A-GTR] Tr of fram

    hana.kim_3928076

      hi. i need your help.

      i tested some our company's product with cypress fram.

       

      i checked cypress  fram's spec.

         

      FM24V02A-GTR spectested data
      minmaxunint測定値
      Fscl-1MHz199.005kHz
      Thigh260-ns2.42us
      Tlow500-ns2.42us
      Tr-120ns130nsNG
      Tf20(vdd/5.5v)120ns25ns
      Thd:sta260-ns1.08us
      Tsu:sta260-ns
      Thd:dat0-ns130ns
      Tsu:dat50-ns1.93us
      Tdh:dat130ns
      Tsu:sto260-ns1.38us
      Taa-450ns520nsNG
      Tbuf500-ns139.75us
      Tsp050ns0-

       

       

      then, Tr and Taa is out of spec.

      i think, it is ok . because Fscl is 200kHz.

       

      are you guys also think it is ok?

        • 1. Re: [FM24V02A-GTR] Tr of fram
          prbd

          Hi

           

          Can you elaborate more on your test procedure.

          Can you also specify in which mode are you working. Is it the high speed mode ?

          Can you share the scope shots also that you used to measure these values.

           

          Thanks and Regards,

          Pradipta.

          • 2. Re: [FM24V02A-GTR] Tr of fram
            hana.kim_3928076

            HI

             

             

            1.  Original circuit(vdd 5v) -> add level change circuit, change the pull-up R and fram(vdd 3v)

             

            After it, I just checked the ac characteristic using osc.

             

            2.  I think it was fast-mode.

             

            3.    I tested it using yokogawa’s osc and probe.

             

            Thanks,

            hana.

                

             

             

            FM24V02A-GTR

             

             

            min

             

            max

             

            unint

             

            UT55A

             

            Fscl

             

            -

             

            1

             

            MHz

             

            199.005

             

            kHz

             

            Thigh

             

            260

             

            -

             

            ns

             

            2.42

             

            us

             

            Tlow

             

            500

             

            -

             

            ns

             

            2.42

             

            us

             

            Tr

             

            -

             

            120

             

            ns

             

            130

             

            ns

             

            Tf

             

            20(vdd/5.5v)

             

            120

             

            ns

             

            25

             

            ns

             

            Thd:sta

             

            260

             

            -

             

            ns

             

            1.08

             

            us

             

            Tsu:sta

             

            260

             

            -

             

            ns

             

              

             

              

             

            Thd:dat

             

            0

             

            -

             

            ns

             

            130

             

            ns

             

            Tsu:dat

             

            50

             

            -

             

            ns

             

            1.93

             

            us

             

            Tdh:dat

             

            0

             

            0

             

            0

             

            130

             

            ns

             

            Tsu:sto

             

            260

             

            -

             

            ns

             

            1.38

             

            us

             

            Taa

             

            -

             

            450

             

            ns

             

            520

             

            ns

             

            Tbuf

             

            500

             

            -

             

            ns

             

            139.75

             

            us

             

            Tsp

             

            0

             

            50

             

            ns

             

              

             

              

             

             

             

            [cid:image005.jpg@01D495EB.9AFA86F0]

            • 3. Re: [FM24V02A-GTR] Tr of fram
              prbd

              Hi Hana,

               

              We looked into the table where you have made all the measurements with the scope. Tr spec as mentioned in the datasheet has a max limit of 120 ns while what you are measuring is 130 ns. Please note this is the rise time of the clock signal that you have to provide to the FRAM on the SCL pin. So, the datasheet clearly states that the rise time of this clock pulse should be max 120 ns while in your case it is 130 ns which means that the FRAM is operating outside the limits mentioned in the datasheet, which is one of the reason why Taa spec is not meeting its timing specs as in the datasheet. We will suggest you to provide a clock pulse from your controller which has a rising time lower than the 120ns spec and check for these results again. (You can check the schematics of your test board to see if you can change something there to improve the rise time.Lowering the resistance or capacitance/load on the SCL line will help you improve the spec)

              As far as 200KHz is concerned you can operate at this frequency as there is no limit to the lower frequency in I2C.

               

              Thanks and Regards,

              Pradipta.

              • 4. Re: [FM24V02A-GTR] Tr of fram
                hana.kim_3928076

                HI

                 

                I have some question.

                You suggested reduce R or C.

                But if I use it the present condition(Tr :130, Taa: 530) is it make other trouble?

                 

                Also I think

                the thing Tr is exceed the 120ns was occurred by probe’s capacitance(maybe 10pF?)

                I'm not sure if it's right or wrong, …

                 

                So reaaly I want to know is

                Is it ok that I use the present condition (Tr :130, Taa: 530)

                • 5. Re: [FM24V02A-GTR] Tr of fram
                  prbd

                  Hi Kim,

                   

                  The parts should be operated under datasheet specified conditions for optimal performance.

                  Under the present condition (Tr : 130, Taa : 530) you are already observing that because the rise time is not within specs you are getting a delay in read as well in form of Taa. Over a period of time it can cause harm to the part as well. We will suggest you to verify once that Tr does not exceeds the spec data and then continue. We can only guarantee optimal performance and functionality of our parts when the datasheet conditions are met.

                   

                  Thanks and Regards,

                  Pradipta.