Other Parts Discussed in Thread: TCAN1042HGV-Q1, TCAN1042HG
May I ask whether TCAN1042HGV-Q1 could use in 24Vsystem?
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Yes, it could. The device is not powered directly from a battery voltage, so the main concern for supporting higher-voltage applications would be the voltage tolerance of the bus pins (CANH/CANL), since under some fault conditions these may short to the battery. This device can support +/-70 V on those pins, which gives plenty of margin to the voltages that could be expected in a 24-V system.
Please let us know if it is not clear or if you have further questions.
This schematic looks good to me. The 1-kOhm series resistance on STB could result in some loss of voltage, so you should make sure that the "VIH" level received is still high enough (> 0.7*VIO) when accounting for this effect.
There is an internal weak pull-up on STB. You can see this by the IIL (input low-level leakage) specification, which ranges from 2 uA (minimum) to 20 uA (maximum). This input current range should be considered when choosing external resistance values (i.e., so that the additional voltage drop across the resistance due to this input current does not result in an incorrect logic state).
Thanks for your kindly reply~
2uA~20uA, can it be equivalent to 50K~500K pull-up resistance, if calculated according to 50K, then the external pull-down 10K, then the high and low level of the external stb input has no effect.
Is it correct?
When the STB pin is not driven by the MCU, then the maximum voltage across the 10-kOhm pull-down is 10 kOhm * 20 uA = 200 mV, which is still low enough since it is below the STB pin's VIL threshold. When the MCU pulls low, the maximum voltage would be even lower: (10 kOhm || 1 kOhm) * 20 uA. When the MCU pulls high, the voltage would be VOH * (10 kOhm) / (10 kOhm + 1 kOhm) = ~0.9 * VOH (neglecting the contributions from the internal pull-up since these could be very small). I just wanted to make sure there was enough margin on the MCU VOH that it could lose ~10% of its voltage and still be above the VIH specification of the STB pin.