Power Consumption
Power consumption estimations are not necessary for most low power designs, but it is a good habit and helps approximate battery life. It is a very important step to ensure your circuit board and components can handle various amounts of current or else your PCB will turn into a survivalist's dream as a fire starter!
Estimating power consumption is very easy and since everything can be ignored except the DC supply voltage and current for each chip. This will be the first time (but not the last) that your spreadsheet about each chip on your board becomes incredibly useful. A new sheet should be created for power consumption estimations with two separate calculations: active mode and sleep mode. Most chips have both of these modes otherwise assume the chip is active in both modes. If you do not plan to use sleep mode in your design, this can be ignored.
Here is an example with the MCU, GPS, and Humidity sensor:
Estimating power consumption is very easy and since everything can be ignored except the DC supply voltage and current for each chip. This will be the first time (but not the last) that your spreadsheet about each chip on your board becomes incredibly useful. A new sheet should be created for power consumption estimations with two separate calculations: active mode and sleep mode. Most chips have both of these modes otherwise assume the chip is active in both modes. If you do not plan to use sleep mode in your design, this can be ignored.
Here is an example with the MCU, GPS, and Humidity sensor:
Keeping tracking of power consumption is important for multiple reasons:
1. Voltage regulator decision - power accounting shows how much current a voltage regulator has to source
2. Resistor/Capacitor physical sizes - larger resistors and capacitors must be used for high power dissipation to prevent burnouts
3. Trace widths - large currents on small traces can cause board failure by overheating the trace
4. Battery life - how large of a battery do you need for a certain battery life
In summary, if you don't keep track of where your currents go, your board can be destroyed due to overheating or burnout! Check out Google images "burned out PCB" for some results of what could happen without keeping track of your heat dissipation!
1. Voltage regulator decision - power accounting shows how much current a voltage regulator has to source
2. Resistor/Capacitor physical sizes - larger resistors and capacitors must be used for high power dissipation to prevent burnouts
3. Trace widths - large currents on small traces can cause board failure by overheating the trace
4. Battery life - how large of a battery do you need for a certain battery life
In summary, if you don't keep track of where your currents go, your board can be destroyed due to overheating or burnout! Check out Google images "burned out PCB" for some results of what could happen without keeping track of your heat dissipation!