PSoC 4 MCU

[Anonymous]

Hello,

       

I am using a CY8C4248LTI-L485 chip to drive an LC circuit to generate a magnetic field. I would like to know the max current I can pull from on these GPIO pins, as there's a lot of confusion in the info I am receiving.

   

On the datasheet, the absolute max current is 25mA, and in the PSoC creator software, the source current on the pin configuration window is only 4mA. However, I have measured more than 55mA on a single pin.

   

Please let me know what is the actual current on rating on these, and if I need to short 4 GPIO pins together to drive higher currents.

       

Thanks!

[JoMe_264151]

Exceeding the max of 25mA may destroy the pin.

   

At 4mA the logical levels of the pin are maintained, When needing higher currents than 25mA you should combine more pins, but do not exceed the maximum power dissipation of the chip.

       

Bob

[Anonymous]

Sorry to ask again, but can you elaborate on the 4mA setting? What exactly does it do?

[odissey1]

        Eirrol, PSoC 4: The maximum total source and sink current for all GPIO pins is 200 mA. PSoC 5 Total source+sink current should not exceed 100 mA for any VDDIO quadrant (or VDDIO pair for the 48-pin packages) See p.3 of the attached AN   

[Anonymous]

Thanks for your reply! However I don't think this applies to the 68 pin 4200L. What I really want to know is if I connect one pin to a load that draws more current than rated, would there be a current limiter built in to protect the circuit?

[odissey1]

        No. The pin will be destroyed. Use external FET. What current/frequency you need?   

[Anonymous]

In order to generate a magnetic field strong enough I would use as much current as possible, at least 100mA, at 500 kHz. 

[Vasanth]

Hi Eirrol,

Drawing more current than the spec may destroy the pin. As per datasheet Maximum Total Source or Sink Chip Current is 200mA. But you have to gang more pins to achieve this. Follow section 6.11 of this AppNote to know how to gang pins for more sink or source current : http://www.cypress.com/file/127101/download

Best Regards,
VSRS

[MoHa_301381]

Hello

I would like to ask why the source current on the pin configuration window is only 4mA in PSoC creator software ?

thanks,

[JoMe_264151]

At the specified 4mA the logical levels of the pin are maintained, thus externally connected electronic will see a valid logical high or low.

Bob

[MoHa_301381]

thanks bob,

did you want to say that connecting the GPIO pin as a "continues and stable" 25mA source is not safe ?

[JoMe_264151]

Not at all. A pin can source/sink as much as the specs say without any damage.

Datasheet for 4000 says per GPIO current +- 25mA max.

Bob