I realise that. But wouldn't Output High be sourcing? Why would sourcing be negative.
I'm just looking at the datasheet. But i suppose LED's for right now.
How are you supposed to know when a manufacter is using - flows from the pin or + flows from the pin?
Read the data sheet and it is defined that way. It goes all the way back to DTL/TTL logic which was good at sinking current, and crummy at sourcing it, so I guess the convention attaches more importance (positive) to sinking...
Whether it's CMOS or not does not affect the direction or polarity of current at a terminal. A high output is source and a low output is sink.The 4017 is CMOS though isn't it?
So Is High output Sinking or Sourcing in conventional terms? Say I I connect the Anode(Positive) end of an LED to an output and th cathode to ground. Would it light on High output or Low?
Texas Instruments show the output current of most of their ordinary Cmos parts at three supply voltages and at any load down to a dead short.The high-state output current of such CMOS devices is pretty whimpy; not enough to drive LEDs directly. Use a hex inverting buffer (4049) between the 4017 output pin and the LED. Wire the the anode of the LED to Vdd, and put a current limiting resistor between the LED's cathode to the output of the buffer
Texas Instruments show the output current of most of their ordinary Cmos parts at three supply voltages and at any load down to a dead short.
The CD4017 has a typical output current of 17mA or a minimum of 8mA into a 3.5V white or blue LED when its supply is 10V and no current-limiting resistor is needed.
Its typical output current into a 2V red LED is 19mA but then the output transistor dissipates 152mW which is too high so a current-limiting resistor is needed when the supply is 10V.
Look at the datasheet of the CD4017B from Texas Instruments.Where are you getting those numbers? If Vdd is 10V it says the typical High current is 900uA.
Look at the datasheet of the CD4017B from Texas Instruments.
Maybe you are looking at an old CD4017A datasheet.
With a 10V supply and a 0.5V output voltage loss then the typical output high current is 2.6mA at 25 degrees C.
Then look at the graph. With a 10V supply the typical output high current into a short to ground is 19mA. Into a 3.5V white or blue LED is 17mA.
The output current of most CD4xxx ordinary Cmos logic ICs are the same.
Here is the typical output high current graph from the datasheet: