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Ixxat CAN-Compact V2 fixed

Posted: Jan 11 2023 3:33am
by PuncturedCell

For any future reference;

I have bought a IXXAT Can Compact V2 a while ago, but it appeared to not work properly.
Never tested it properly

The USB-part checks out correctly, but no CAN msg'es are ever received or transmitted AFAIK.

I probed the PCB a bit & looked up some data sheets.

Appeared that the VP251 (SN65HVD251D) wasn't functioning properly. Output was always 3.8V on CAN_H and 0v on CAN_L (Compared to V-) compared to 2.5V on both on my other Ixxat.

This didn't correspond with the value's coming into the chip according to the datasheet. (floating or HIGH = recessive state, LOW = dominant state, it was HIGH & Dominant state) Also, not sure if Can_L ever reaches 0v.

Another notice; it got quite warm, together with the DC-DC converter. There was only 10 or so ohm's between VCC & Gnd (while off, with DMM checked) - After replacing the VCC & GND were in the 400-500 range, which could click with the dc-dc converter's coil.

Bought a new SOIC VP251 part nr #SN65HVD251D by TI and replaced the one in the IXXAT.

Unfortunately at the cost of a tiny capacitor (10-50nF?) below the chip (In the picture it looks sizeable but its 1.2x0.6mm or something)

I think it's a noise eating cap on the vcc and gnd ('decoupling' cap) so not too worried about the functionality loss since its already behind a dc-dc converter and optocoupler
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