2 Replies Latest reply on Jul 20, 2016 11:45 PM by userc_39496

    Start up time for PSOC4

      I'm having some issues with my hardware design, which is using the PSOC4 BLE chip (CY8C4217LQI-BL473 to be exact).


      I'm testing my hardware using some pretty simple code, which I have attached.  It simply flashes my RGB LED once its all up and running.  It also sets a digital output pin high (Pin_PSU_EN), which is the key to keeping my hardware PSU operating.  This output turns on a PNP that bypasses a bootstrap resistor and allows enough current to flow from my DC rail to keep everything operating once the IC has started up.


      The issue I am having is that the time it takes between when my PSU chip sets XRES low (and hence brings the chip out of reset) and the time the code sets Pin_PSU_EN high (which then enables everything to operate) appears to be over 500msec!!!


      I'm measuring this time period by triggering on the signal from my PSU Power Good pin (which connects to XRES on my IC) and monitoring the Pin_PSU_EN pin, and I am seeing a time delay in the order of 500msec.


      This seems a ridiculous amount of start up time - I would have expected something in the 500us range, at worst.  What this means is that my hold up cap, which needs to supply the ~3mA of current for the time it takes the Pin_PSU_EN pin to be activated needs to be stupidly large (something like 220uF or larger).


      Is this 500msec start up normal?  Is there anything I can do to reduce it?