Editing PG31 GPS RS232 Dev Board
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C2 ([[10uF Tantalum Capacitor]] in this case) is a basic decoupling cap. 10-100uF is adequate but should be rated for 15-25V. | C2 ([[10uF Tantalum Capacitor]] in this case) is a basic decoupling cap. 10-100uF is adequate but should be rated for 15-25V. | ||
− | U1 is the LM317 (or LM1117 in SMD form) adjustable | + | U1 is the LM317 (or LM1117 in SMD form) adjustable voltage regulator. It will take in some larger voltage and output a set voltage. The output voltage is set with two external resistors. R1 is historically 240 and value for R2 is different for different required output voltages. In our case, we want 3.3V out of the regulator, so R2 is set to 715. The LM317 is good because it is variable, the SOT-223 package is nice becuase it can take a relatively large voltage on the input (25V max I believe?) and has decent heat dissapation. |
C1 and C3 are decoupling caps that help clean up the output transcients and noise. | C1 and C3 are decoupling caps that help clean up the output transcients and noise. |