Hi Team i designed the schematic shown below for my automotive GPS Tracker
so I'm Just thinking that is it the correct way to do this for long run
or any better way to do this
please give your suggestions and recommendations.
Thanks in Advance
Hi, if you need to regulate the voltage, there are integrated circuits that regulate the voltage linearly and are very precise, if you need 3.3 V there is the LD1117V33 which if you apply an input voltage ranging from 4.5v to 15v in output you will have 3.3v.
or the LM7805 if you power it between 7v and 25v, you will have 5v at the output.
Without a heatsink they can be fine with small currents, but the higher the current and the higher the supply voltage, it is better to put a small heatsink.
look carefully at the datasheets in case.
This can cost battery lifetime. In battery powered applications it will be more economic to use more efficient (step down) regulators.
Linear regulators such as the 7805 drop voltage by burning it as heat and they also have a quiescent current requirement. Diodes and resistors do not have the additional quiescent current so are more efficient. A SMPS (Switch Mode Power Supply) is more efficient and will give you a greater battery life but they also have a quiescent current which needs to be considered. The higher the current the more efficient the SMPS (Buck/Boost/SEPIC) are.
It eventually boils down to the circuit requirements. If it is a low stable current resistors or diodes will work just fine. If it is not stable then diodes will work. You will need to weigh this against other forms of regulation. Also linear regulators need external capacitors to remain stable which adds parts to the circuit.
In the end it depends on the circuit and the designer's experience.
Voltage dividers using resistors are very common for low current applications such as A/D and port inputs.
Neither the main regulator nor the auto bat circuit represents a "good" design. Perhaps if you posted your goal and what these circuits are supposed to do you would get more help.
For instance, in the main regulator. If the goal of D17 is to protect from reverse voltage then it should be right at the regulator Vout (pin4). If its to drop voltage then it should be removed and R81 & R83 should be calculated to provide 3.8 v output.
Curious, it seems you goal is to drop 5V to 3.8 volts. The 3.8V value is not a common voltage requirement. Can you tell us what is needed for you GPS circuit?
For the GPS, I recommend to use a switching stepdown 3.3V regulator like this one, and no diodes.
What is the battery supposed to do?
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