I'm testing a LTC490 with a hand-turned encoder.
As I only have one IC, I tried testing only one channel (A).
I wired as follows:
Pin 1 to 5v, Pin 2 to pin header (to read output voltage with a voltmeter), Pin 3 to CLK (Encoder A output), Pin 4 to GND,
Pin 5 to Pin 7, Pin 6 to Pin 8
The idea was to use the LTC490 to encode the signal, and then feed it back into the IC for decoding. As the frequency is so low, I saw no need to use a terminating resistor, and instead made a direct connection.
It would seem that the LTC490 is providing a path of no resistance between the Vin and GND pins, which caused my 5v power supply to melt, and emit smoke. Can anybody explain what's causing this? I suspect it down to the way in which I've wired it, although I have no idea why.
On closer inspection of the wiring, I realised I was feeding 5v into GND, and 0V into VDD, which I'm going to assume is what caused the short circuit.
Slightly unrelated, but the test schematic includes capacitors and a resistor (Figure. 2 in the datasheet). Can anybody tell me what these are needed for? I've wired as shown, minus the capacitors and resistors, and it seems to work just fine (of course, I'm using a low PPR encoder, turned by hand). Are they to remove AC noise?