How much current can this 74HC245 handle on each output pin? Is it 20mA, 35mA, or 70mA?
I don't understand what the difference between output current, output clamping current, and supply current is.
How much current can this 74HC245 handle on each output pin
buffercurrentdatasheet
Related Solutions
What it means by 6mA at 5v, is that at 6mA, the output voltage level of that output will be fairly close to 5v (or VCC). The more current you source out of an output, the lower that voltage will be. This is called Voltage Droop, or Sag. Same goes for sinking current, with the voltage level rising, so instead of it being 0.0 or 0.1, at 20mA it might be 1v.
Notice that at a VCC of 4.5V, Voh (Voltage Output High), at Ioh (Current output high) -20µA (or -0.02 milliamps, the - indicating sourcing current) the typical is 4.499 volts. While at -6 mA, the typical is 4.3? Your output just lost 0.2v with only 6 mA of current draw. Anything more, and that drop will increase an untested amount. Some datasheets actually have a graph for this. This one does not. So you can draw more than 6mA, up to the max Io output current of 35mA (plus or minus) on a single output, but the voltage level will change to the point where it might not be useful to you. Ex. At 35mA, you might not be able to light an led.
There's a taste of positive feedback (19uA typically) that allows you to leave unused data inputs floating.
Sort of like this (but in the real chip the resistor would be more of a current source/sink formed by a couple of MOSFETs).
simulate this circuit – Schematic created using CircuitLab
If the input was left open and not pulled high or low by the resistor (or current source) it could drift around and the gate might draw excessive current or it might create interfering EMI. Note that this does not add to the quiescent current draw.
It's called "bus hold" because the last level that the input was forced to (high or low) is held (weakly).
Best Answer
Icc is the max current to the Vcc pin. Ignd is the max current to the ground pin. Both of these are listed as 70 mA. The clamp values are the max current through the ESD protection/clamping diodes that connect each pin to Vcc and GND. Current will only flow through these diodes if you apply a voltage to an input or output pin which falls outside the supply rails (greater than Vcc or less than GND). Both of these are specified at 20 mA. The output current is how much current the driver on the pin can actually supply, which is specified as 35 mA. Note that you cannot draw 35 mA from more than two pins at the same time as this would exceed the Icc/Ignd limits.
The interesting thing about these chips is they actually have a spec for the current through the ESD protection diodes. This means that it is actually perfectly reasonable to connect the inputs to a relatively high voltage source (say, 12V) and only use a series current limiting resistor for the level translation.