I am looking to make a logic chip tester. There are a ton of variety of logic chips out there, as I understand. The two questions I have are, because the VCC and GND pins of logic chips can vary, not always the last pin (GND) on the left side of a chip and the 1st pin (VCC) of the right side of a chip.
1) I want to be able to find out the minimum input/drawn current or a chip. Looking at the datasheet for the HC595, for example, I see Iik (input clamp current) is +/- 20mA. Is that 20mA the max current consumption for this chip? I could be smart and test this chip with individual output turned on, thus consuming around 10mA each test or turn on all 8 outputs, thus consuming 80mA! Could I use even an ATMEGA's I/O pins to source the VCC pin of this chip or to ground the GND pin of this chip with a zero output? Of course, I do realize that I cannot source 80mA out of an ATMEGA's GPIO pin. That brings to the 2nd question below.
2) If there is a chip I can use to be able to provide a chip's GND or VCC, that would be good to use. And this "magic" chip could source more current? Transistors? MOSFETs, etc.? Given a pin of the chip to be tested, I want to be able to interface to that chip's pin either as an input/output or GND or VCC pin.