I.mxRT GPIO max sinking & sourcing current

HeMyFAE — Thu, 30 Jan 2020 00:45:05 GMT

Dear i.mxRT,

One of my medical customers who is using a RT64 is also looking for the GPIO max sinking and sourcing current specification for documentation purposes. Please let me know where I can find this info.

I searched in both the DS and RM but there are no such data. Please advise!

Regards,

Re: I.mxRT GPIO max sinking & sourcing current

Yuri — Thu, 30 Jan 2020 05:06:57 GMT

Hello,

GPIO DC parameters in i.MX Datasheet(s) provide typical Ioh and Iol values.

Generally the GPIO drive current is affected by the configuration of the buffer. Customers

can use DSE field in the controlling IOMUX registers to set the drive strength. There are also
a slew rate controls in those registers which may also have an effect

The best way to estimate currents is to use the IBIS model for the IO(s) you care about.

IBIS file shows tables with the buffer drive current across a range of pad voltages. You can look

through the list to find the current at the voltage of interest.

Note, that the IBIS model covers a wider range than the conditions allowed in the datasheet so

not everything in the IBIS model is an allowed use case. Also, these currents in a real case would

be transient lasting only nanoseconds or less. This does not imply you could run the buffer at that

current for an extended period of time.That would cause overheating on the part and create reliability

problems.

i.MX RT 1064 Datasheets contain “GPIO output buffer average impedance” tables. Parameter Output

Driver Impedance allows to estimate

1) max possible (short circuit) current, as following: I = Vout / Impedance (143 mA =3.3V / 23 Ohm);

2) real current, depending on external load; I = Vout / (Impedance+R_load), so to get 10mA, external

load of ~300 Ohm is needed, assuming DSE =111.

Of course it is needed to take into account thermal considerations in order to avoid device damage.

Also:

Maximum output current io pin

Regards,

Yuri.

topic I.mxRT GPIO max sinking & sourcing current in i.MX RT Crossover MCUs

I.mxRT GPIO max sinking & sourcing current

Re: I.mxRT GPIO max sinking & sourcing current