2 Adjustable Feedback Voltage

While adjustable LDOs offer flexibility to meet non-standard voltage requirements, the external resistor feedback network required to set the output can significantly increase the total system quiescent current (I_Q). Because the current through the divider is inversely proportional to the network's total resistance, the choice of resistors directly impacts the system's overall power dissipation. To optimize efficiency in battery-powered applications, systems must utilize high-impedance resistor networks to minimize the parasitic current drawn from the output.

However, this optimization must be balanced against the requirement for regulation accuracy. If the resistor values are excessively high, the feedback current can become comparable to the LDO internal leakage current, creating a voltage error at the feedback pin that shifts the output from the intended output. To reconcile low system-wide power consumption with high precision, a good approximation is to maintain the current flowing through the divider is at least 100 times greater than the LDO's maximum expected leakage current. This approach allows for significant reduction in total system I_Q without compromising the stability or accuracy of the voltage regulation.