MCP2551 Slope Resistors

[dara hayes]

Hello all
am using a combination of phillips transceivers and Mchip parts
82C251 and MCP2551 , the levels from the phillips parts are .4v
larger than the Mchip output bus swings and the Mcp parts have poor
shape with respect to the shape of the phillips bus outputs
The Phillips transceivers are all on the CCS can kit and the Mchip parts
are on my external prototpyes and they each have a slope resistor of
4.7k whereas the phillips parts all have 10ohms for the same slope resistor , checking with the Data sheet for mchip parts the value of 4.7k
which was copied off the circuit for the Mchip can dev kit doesnt seem to
be on the scale of the graph for SLOPE RES versus speed

does anyone know what value these resistors should be , also despite termination of my bus with 120 ohm each end
the bus output from the Mchip parts seems to suffer from under shoot and some occasional spikes up to 5V level when measuring between CAN H and ground. This is not the case on the much cleaner output from the
Phillips parts on the CCS dev kit

thanks
Dara Hayes

[dara hayes]

Hello
CANCEL MY LAST
Short the pin for high speed , missed the vital third mode "high speed"
was too concerned with actual value of resistor , I am using double screened cable so I dont need SLOPE control , a short restores the shape
but still have different level (about 0.4v more with phillips parts)
from the two types of transciever

Dara