LP2985LV Datasheet, PDF (9/15 Pages) National Semiconductor (TI) – Micropower 150 mA Low-Noise Low-Dropout Regulator in SOT-23 and micro SMD packages for Applications

LP2985LV
150ĆmA LOWĆNOISE, LOWĆDROPOUT REGULATOR
WITH SHUTDOWN FOR OUTPUT VOLTAGES <2.3 V
SLVS552 − OCTOBER 2004
APPLICATION INFORMATION
capacitors
input capacitor (C_IN)
A minimum value of 1 mF (over the entire operating temperature range) is required at the input of the LP2985LV.
In addition, this input capacitor should be located within 1 cm of the input pin and connected to a clean analog
ground. There are no Equivalent Series Resistance (ESR) requirements for this capacitor and the capacitance
can be increased without limit.
output capacitor (C_OUT)
As an advantage over other regulators, the LP2985LV permits the use of low ESR capacitors at the output,
including ceramic capacitors that can have an ESR as low as 5 mΩ. Of course, tantalum and film capacitors
can also be used if size and cost are not issues. The output capacitor should also be located within 1 cm of the
output pin and be returned to a clean analog ground.
As with other PNP LDOs, stability conditions require the output capacitor to have a minimum capacitance and
an ESR that falls within a certain range.
Minimum C_OUT: 2.2 µF (can be increased without limit to improve transient response stability margin)
ESR range: See Figures 1 and 2
Figure 1. 2.2-µF Stable ESR Curves
Figure 2. 4.7-µF Stable ESR Curves
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