I'm designing a project which involves a microcontroller sending data over SPI to two SN74HC595N shift registers which, then control some level shifters to turn on and off some 12v end devices. (The MC and the register circuit are on two separate boards) I want to power the shift registers and the rest of that circuit on 4v using an LM317 with an input voltage of 12v.
I'm a beginner in electronic engineering, there is so much I still must learn. Please bestow upon me the knowledge of the masters, for I am but a young padawan.
The heat dissipation on the datasheet for the LM317 is about 39 degrees C/W. I really don't want to stick a heatsink on this PCB because, well, I'm lazy. I am trying to determine the resistance in my circuit so that I can calculate the heat that will be on this regulator. This is where my combat level in electronics becomes apparent. Looking at the datasheet of my 595's, I can't work out where it tells me either the resistance across the IC, or the maximum current would be. On the datasheet from TI, it's figure 6.1 (I think). Basically what I'm trying to do here is determine the total resistance in my circuit so that I can use Ohms Law to give me wattage so that I can apply that value to the thermal dissipation on the LM317. In a simple circuit with easy components, I can do that. I don't know how to work out more advanced circuits' resistance with ICs and the like. How do I find out my resistance in a circuit with ICs in it? Where can I find that information?
Any help would be appreciated. I know, I'm a noob, but I want to learn. Can't blame a guy for learning.
I'm a beginner in electronic engineering, there is so much I still must learn. Please bestow upon me the knowledge of the masters, for I am but a young padawan.
The heat dissipation on the datasheet for the LM317 is about 39 degrees C/W. I really don't want to stick a heatsink on this PCB because, well, I'm lazy. I am trying to determine the resistance in my circuit so that I can calculate the heat that will be on this regulator. This is where my combat level in electronics becomes apparent. Looking at the datasheet of my 595's, I can't work out where it tells me either the resistance across the IC, or the maximum current would be. On the datasheet from TI, it's figure 6.1 (I think). Basically what I'm trying to do here is determine the total resistance in my circuit so that I can use Ohms Law to give me wattage so that I can apply that value to the thermal dissipation on the LM317. In a simple circuit with easy components, I can do that. I don't know how to work out more advanced circuits' resistance with ICs and the like. How do I find out my resistance in a circuit with ICs in it? Where can I find that information?
Any help would be appreciated. I know, I'm a noob, but I want to learn. Can't blame a guy for learning.
