| ??? 06/13/07 04:12 Read: times |
#140642 - No violations Responding to: ???'s previous message |
Dear Kai,
Also, the current loop area of input signal should be as minimal as possible. But you extend this area over the whole voltage divider circuitry plus multiplexer circuitry, which could add some noxious inductivity, causing an internal failure the datasheet say source impedance shouldn't exceed 10Kohms or be able to charge 20pf capacitor in 1.5 clock pulses. Assuming even total 50pf capacitance and clock frequency of max 200Khz please calculate the max impedance source can have. But my point is that Ch1 ckt has actual source impedance of 64ohms (100ohm paralled by some 120 ohm internal of CT) so that channel should be least susceptile to any interference capacitive or inductive (!). So why does this interefernce comes? Manufacturers may hide their problems behind the datasheet specifications. I have sent Microchip my code and ckt diagram and asked them to show if any violations are there. There stock reply is device works in their daughterboard and you have to this and that for so and so which is in datasheet. Why should anybody would approach them if device works as in datasheet. By the way nobody is commenting on deficiencies of code or other things. regards, psd |
