Positive linear regulator Li'lBoard page.
Model number: LB2.01.
Description: This board works as a regulator to provide a smooth, fixed positive voltage when supplied with a larger positive voltage.
Applications:
•Ideal in conjunction with either a L'il2.07 (Vehicle power input) or a L'il2.08 (Wall Wart input) to produce your system's desired operating voltage.
•The board can be operated as a current source (useful for high power LEDs): the support software handles this mode as well as the normal voltage source mode.
•A useful set-up is a 3.3/5 V one where an external switch shorts out R3 (use 324 Ω, 1% for this application), leaving R2 (392 Ω, 1%) to produce the lower voltage.
Features:
•The board is designed so that the resistors that determine the output voltage can be combinations of both through-hole and SMD devices. One use of this is to parallel a (higher value) through-hole device to trim the output voltage in critical applications. Additionally, the terminals where the resistors are mounted can be used to configure a dual selectable voltage regulator (using a switch to ground), or a variable regulator with a lower limit on voltage if an external potentiometer is used.
•The input voltage can be fed into the unit directly or via an on-board diode. The diode provides protection from reverse voltages, however it will add to the dropout voltage of the regulator.
•Either a TO-220 or a surface mount version of the regulator can be installed.
•A heatsink can be mounted on the TO-220 package version.
Key components: LM317
Support page: Click here
Restrictions: Can only produce an output voltage less than the input voltage, and there has to be at least a 1.5 V difference between the input and the output (more critical at higher currents) to ensure regulation (this is called the dropout voltage).
Images:
Click on image for full (PDF) schematic
Vin max: 40, depending on rating of C2
Vin min: about Vout + 1.5 (higher if using the diode input terminal)
Vout min: 1.25
Vout max: 37, depending on rating of C4
SPI: N/A.
Tenth centers: YES