2 Replies Latest reply on Mar 4, 2014 3:27 AM by dmitri.krasnykh

    Ganging HSB# pins

    dmitri.krasnykh

      I would like to use 8 NVSRAM devices CY14B108N-BA25XI parallel. Of course with address decoder for CS# lines.

         

      Is it possible connecting all HSB# pins together (and ext. pull-up 10k) and uses one microprocessor GPIO for Hardware STORE/RECALL operation only?

         

      Thanks in advance for any help.

         

      dk

        • 1. Re: Ganging HSB# pins
          zsk

          Yes, it is possible to GANG the HSB pin of multiple CY14B108XX parts and use a single controller IOs to control it. You might be aware that HSB has an internal weak pull up resisitor of ~50K on these parts, therefore putting 8 devices in parallel will bring down the equivalent resistnace below 6.5K. Hence an external pull up of 10K is really not required on HSB in this scheme. However, even if you apply an external pull up of 10K with 8 devices gangegd for HSB , its not going to pose any issue as it will only reduce the effective resistance further below 4K.

             

          Hope this helps.

             

          Thanks,

             

          Shivendra Singh

          • 2. Re: Ganging HSB# pins
            dmitri.krasnykh

            Dear Sir,

               

            I reopen my case because of changes in the AN43380.

               


            AN43380 Rev.C

               

            The output HSB is an open drain, active low driver and allows multiple HSB pins to be tied together and controlled by a single controller I/O pin in a system.

               


            AN43380 Rev.D

               

            Removed the description on connecting pins of multiple nvSRAM devices together (ganging of the pins).

               

             

               

            I need a comments from Cypress.

               

            Is it still possible “multiple HSB pins to be tied together and controlled by a single controller I/O pin in a system” or it is wrong information?

               

            Thanks,

               

            dk