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.
