I'm looking to use the SN65HVD230 CAN transceiver but had a question about the current consumption.
Datasheet: http://www.ti.com/lit/ds/symlink/sn65hvd230.pdf
In table 8.3 Recommended Operating Conditions, it said the high level output current for the driver is -40mA and the low level output current is 48mA. However in Table 8.5, it is said that the supply current (Icc) has a max recommended current of 17mA. How can the driver current consumption be greater than the overall supply current ?
How do I calculate the overall current consumption of the bus ? The datasheet seems to only talk about the current consumption of the receiver and driver, but not the actual CANH and CANL lines?
Best Answer
The max supply current of 17mA is with "no load". That means there is nothing on the output to supply output current into. Any output current, up to the limits in Table 8.5, is in addition to this rating.
This approach is often used in datasheets because it gives you the values of current "consumed" by the device. Output current is consumed by external loads (in this case, the bus) so is useful to treat separately. The necessary output current is very dependant on the external environment, rather than the behaviour of the IC itself. Indeed, often these driver ICs have a separate supply pin just for the load. While this one does not, you can still see from the block diagram that the output could have its own rail.