1 Reply Latest reply on Feb 18, 2020 11:55 PM by TakashiM_61

    MB90F598G failure to start, changes port2 direction to output when /RST pulled low



      We have used this processor for 15-20 years in a circuit that has not been changed since 2005. Now we experience that processors with production dates 1834 NO E1 and 1845 NO2 E1 are failing the test: processors can be flash-programmed but will not start execution of program.

      Only some of the processors with the above production dates fail; presently it concerns 200+ processors that have already been mounted on PCBs. In addition to these we have found 40+ failing processors in a screening setup consisting of a normal production PCB with a socket for the processor. Presently all processors are tested in this socketed PCB before they are soldered onto a PCB. All processors that work in the socket also work when soldered.

      We noticed that the VCC current increased by 250mA when /RST was pulled low and we found out that the unused Port 2, which is set to input and directly connected to VSS, changed direction from input to output (high) when /RST was pulled low. We have not measured current on the single port-pins but the 8 pins on Port 2 source a total of 250mA when /RST is pulled to VSS.

      If /HST is pulled low,  the current decreases to the normal level.

      The change of port-direction indicates that the port direction registers are changed by /RST, which should not happen.

      Some of the failing processors are simply short-circuited between VCC and VSS.

      Please advise how we should proceed from here as we also experience long leadtimes for new deliveries to replace the failing processors.

      BR Kim

        • 1. Re: MB90F598G failure to start, changes port2 direction to output when /RST pulled low

          The 16LX series can be driven in different modes which are selected by the MD0 .. MD2 pins.

          There are two settings which are used for the user:

          1. MD2=0; MD1=1; MD0=1 à internal vector mode
          2. MD2=1; MD1=1; MD0=0 à Flash memory serial programming mode


          Find more information in the 90590 hardware manual at chapter 7.2



          For both mentioned settings, Port2 pins are in high-z mode (input) in case of /RST pin is pulled low.

          However, for some other non-user modes, Port2 pins are switched to active high in case of /RST pulled low.

          On a eval board (e.g. Flash-CAN2-100P-M06) you can test the behavior of Port2 pins for following settings:


          MD2=0; MD1=0; MD0=0

          MD2=0; MD1=0; MD0=1

          MD2=0; MD1=1; MD0=0

          MD2=1; MD1=0; MD0=0

          MD2=1; MD1=0; MD0=1


          All of them are not allowed for user.


          Please check and measure the voltage levels on the MCU pins for the pins MD0 (pin 49), MD1 (pin50) and MD2 (pin51) whether your configuration on the affected boards is wrong. Best way to prove the behavior is to trigger on falling edge of /RST and measure MD0 .. MD2.