Annirak Wrote:
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> What the datasheet is unclear on is the minimum
> acceptable input high voltage. I will have to do
> some digging on that.
Yes that was my point about. It doesnt have Vih and Vil at all. Because its current controlled. E.g. "current device" being controlled by current to its input. Sort of speaking it doesnt have Vih and Vil (voltage input high and low), in same terms it should of had Iih and Iil (curent input high and current input low), if it would of had a "current static discipline". That *was* my point, its a current device, it takes current level for input, while uC outputs voltage. At same time the others, microchip's mosfet drivers take voltage for input, i think coz they are made for microchip's microcontrollers and "they speak same language" - voltage.
My point was about that, the input side (from the microcontroller - uC). Simply because our uC outputs voltage, it makes sense to me to use a device which input is controlled by voltage instead of one being controlled by current. In the same way but reversed, if my uC output would be as current level, then it would make more sense to pair it with a mosfet driver that takes input as current like this one. This is about uC and driver sort of speaking same language / static discipline.
Again as i said first time, this is my opinion, my preference, etc. To pair a voltage output device with another voltage input device. If its voltage both for uC output and device input this is simpler and to me feels more tangible, control points are clearly stated, and i'm with keeping it simple as much as possible.
On the other hand there have to be billions of applications where an uC pin with a digital output (voltage lvl) controls a traditional transistor (current input) instead of a mosfet (voltage input), and there is nothing wrong with it. On the same page we could of used a darlington transistor or IGBTs (current input devices) to control heated bed and extruder instead of using mosfet (voltage input) and this should of also worked more or less the same - perhaps except very high freq.
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> What the datasheet is unclear on is the minimum
> acceptable input high voltage. I will have to do
> some digging on that.
Yes that was my point about. It doesnt have Vih and Vil at all. Because its current controlled. E.g. "current device" being controlled by current to its input. Sort of speaking it doesnt have Vih and Vil (voltage input high and low), in same terms it should of had Iih and Iil (curent input high and current input low), if it would of had a "current static discipline". That *was* my point, its a current device, it takes current level for input, while uC outputs voltage. At same time the others, microchip's mosfet drivers take voltage for input, i think coz they are made for microchip's microcontrollers and "they speak same language" - voltage.
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Low input current of 1mA to deliver 4A output current
My point was about that, the input side (from the microcontroller - uC). Simply because our uC outputs voltage, it makes sense to me to use a device which input is controlled by voltage instead of one being controlled by current. In the same way but reversed, if my uC output would be as current level, then it would make more sense to pair it with a mosfet driver that takes input as current like this one. This is about uC and driver sort of speaking same language / static discipline.
- * If uC output controls the voltage level, and driver is controlled by voltage level, then its easy to calculate the exact time it takes do anything, including precise switching point. Its just a rising edge of voltage and that's all the math there is, and its exact. Since the uC gives "on/off" signal, we can easily calculate how much time till driver registers input to switch on/off.
* But, if the uC pin voltage is linked to a device that takes current as input, then its probably not impossible, but at least a bit harder to math out what is exactly the point when driver input switches states. For example, theoretically could solve this with a voltage to current transfer function. But afaik the uC pin lacks the capacity to offer precise current control as output, and this gives room to a little uncertainity. At least the way i see it, the precise point where input state determines driver to switch on-off, that point is a little more "fuzzy".
Again as i said first time, this is my opinion, my preference, etc. To pair a voltage output device with another voltage input device. If its voltage both for uC output and device input this is simpler and to me feels more tangible, control points are clearly stated, and i'm with keeping it simple as much as possible.
On the other hand there have to be billions of applications where an uC pin with a digital output (voltage lvl) controls a traditional transistor (current input) instead of a mosfet (voltage input), and there is nothing wrong with it. On the same page we could of used a darlington transistor or IGBTs (current input devices) to control heated bed and extruder instead of using mosfet (voltage input) and this should of also worked more or less the same - perhaps except very high freq.