I'm trying to choose the best values of resistors given the stock I have so that I can deliver sufficient power and current to an HM-TRP radio module.
In this circuit, I used the 100K resistor instead of the 8051 microcontroller because I'm trying to simulate the microcontroller impedance when the port is not set low in software. If I set the port low in software, then the left-most transistor emitter is grounded.
The main problem I have here is that when I used a simulator to measure current, Its registering between 197mA and 203mA, yet I want to provide the HM-TRP radio module enough current so it can function.
The problem with those current values to me is when I calculate wattage, it (according to the datasheet I found) exceeds the maximum value by approximately 25mW.
- I can understand that if I exceed the wattage by a large amount, I might get a melted transistor, but what about by a small amount? Does it matter?
- And what if the wattage is exceeded for under 100ms at a time?
For my circuit, the 15 ohm resistor is 1W, and the other resistor is 1/4 watt. Both are carbon film 5% tolerance. The transistors are both PN2222 and the 3.3V supply is fed from 5V (that directly feeds the 100K) through an LM1117-3.3 regulator.