Hi!
I'm considering switching from a Teensy 3.6 to a Teensy 4.0 and was wondering what the current rating for the pins is. Unfortunately the Teensy 4.0 documentation is still pretty bare-bones, so I checked the datasheet of the i.MX RT1062 (https://www.nxp.com/docs/en/nxp/data-sheets/IMXRT1060CEC.pdf) and in Table 22 it seems to indicate we have only 1µA push-pull capability, and marginally more with pullups/-downs, which equals something like a 3MOhm output impedance. Other micros usually have something in the low mA range, for example the Teensy 3.6 specifies 25mA (https://www.nxp.com/docs/en/data-sheet/K66P144M180SF5V2.pdf, section 1.4). Probably I'm reading the datasheet wrong and this is the expected current when a pin is configured as input, where such a high impedance would make total sense.
I can't believe I've read the datasheet correctly that the 1062 has such a low current capability, but this thread on the NXP site seems to confirm that (https://community.nxp.com/thread/505035). In that thread and others (https://community.nxp.com/thread/380134) Table 12 is referenced for the maximum GPIO pin current, with the formula Imax = N * C * V * F/2 where N=pin count, C=pin capacitive load, V=io-voltage, F=pin change rate. This formula allows estimating how much current the whole GPIO block will additionally draw, if used with the respective parameters. But that says nothing about its capability to do so. So what's the maximum rating for current sourcing and sinking of the digital output pins on the Teensy 4.0 per pin and in total? If it's truly just 1µA, what is the recommended buffer to make Teensy 4.0 pins usable for any realistic microcontroller scenario?
I'm considering switching from a Teensy 3.6 to a Teensy 4.0 and was wondering what the current rating for the pins is. Unfortunately the Teensy 4.0 documentation is still pretty bare-bones, so I checked the datasheet of the i.MX RT1062 (https://www.nxp.com/docs/en/nxp/data-sheets/IMXRT1060CEC.pdf) and in Table 22 it seems to indicate we have only 1µA push-pull capability, and marginally more with pullups/-downs, which equals something like a 3MOhm output impedance. Other micros usually have something in the low mA range, for example the Teensy 3.6 specifies 25mA (https://www.nxp.com/docs/en/data-sheet/K66P144M180SF5V2.pdf, section 1.4). Probably I'm reading the datasheet wrong and this is the expected current when a pin is configured as input, where such a high impedance would make total sense.
I can't believe I've read the datasheet correctly that the 1062 has such a low current capability, but this thread on the NXP site seems to confirm that (https://community.nxp.com/thread/505035). In that thread and others (https://community.nxp.com/thread/380134) Table 12 is referenced for the maximum GPIO pin current, with the formula Imax = N * C * V * F/2 where N=pin count, C=pin capacitive load, V=io-voltage, F=pin change rate. This formula allows estimating how much current the whole GPIO block will additionally draw, if used with the respective parameters. But that says nothing about its capability to do so. So what's the maximum rating for current sourcing and sinking of the digital output pins on the Teensy 4.0 per pin and in total? If it's truly just 1µA, what is the recommended buffer to make Teensy 4.0 pins usable for any realistic microcontroller scenario?
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