Discussion and questions related to the course Practical Harness Construction - Club Level
Hi silly question,
when using a hall effect sensor requires a pull up, in haltech elite ecus there are two pull up options- 2.2k to 5v and 550ohm to 5v.
other options require an external pull up resistor, my question is if you use a 2.2K 5v internal pull up do you still connect the sensor power to 12v as the haltech diagrams show or does a 5v pull up require a 5v power?
is there any advantage to using 5v or 12v? (excluding the internal pull ups) i would assume 5v is more stable but does the lower voltage have any negative side effects?
i suspect its the later, given i am about to terminate my loom using internal pull ups i would like to be some what sure.
the sensor is a cherry hall effect sensor PN: GS100502
The pull-up values on the ZF datasheet assumes the Pull-up is connected to the same VCC as the sensor power, in automotive scenarios it may not be. The important thing for choosing the correct pull-up is the voltage that the pull-up is connected to which will be 5V in your case regardless of how you power your sensor.
The haltech 2.2K pull-up may be a little light and I have had experience with that sensor not working well with high tooth counts if the pull-up is too weak (on a Link ECU's which has a 4.7K pull-up). The data sheet shows the sensor output can sink 20mA, so you will be fine to use the 550Ohm option (5V/550ohm = 9mA).
Adam, thank you very much for your help even though its not a link ecu. for the record i wish i did buy a link due to haltech locking down the CAN network tighter than fort Knox!
i used the standard pull up and the car runs well so far.
i did note the home percentage of travel is about 59%. I'm curious if any one knows what this is referring to and how to explain it?