Texas Instruments LP38502SD-ADJEV
This Evaluation Board highlights the LP38502SD-ADJ, a 1.5A Low-Dropout (LDO) linear regulator in the LLP-8 package which has an adjustable output voltage (set by external resistors).
Changing the Output Voltage
The resistors R1 and R2 set the output voltage. The equation to determine output voltage is:
VOUT = VADJ x (1 + R1/R2)
where VADJ is typically 0.6V.
The board has installed values of:
R1 = 19.1k
R2 = 6.04k
Which sets the output to 2.5V. R1 can be adjusted to change the nominal output voltage to other values. The minimum output voltage which can be set is the ADJ pin voltage, which is approximately 0.6V. This is obtained by installing a jumper or low value resistor (less than 10 at R1. The maximum usable output voltage is limited by the maximum input voltage which is 5.5V. Since rated dropout voltage at full current is 0.375V, this means the maximum? usable output voltage for full current operation is about 5.1V.