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APPLICATION INFORMATION

Capacitors

Load Current − mA

Load Current − mA

Load Current − mA

Load Current − mA

LP2981

100-mA ULTRA-LOW DROPOUT REGULATOR

WITH SHUTDOWN

SLVS521E – JULY 2004 – REVISED MARCH 2008

A minimum value of 1

µF (over the entire operating temperature range) is required at the input of the LP2981. In

addition, this input capacitor should be located within 1 cm of the input pin and connected to a clean analog

ground. There is no Equivalent Series Resistance (ESR) requirement for this capacitor, and the capacitance can

be increased without limit. A good quality ceramic or tantalum capacitor can be used.

As a PNP regulator, the LP2981 requires the output capacitor to meet both a minimum capacitance and ESR

value. Required ESR values as a function of load current are provided for various output voltages, load currents,

and capacitances (see Figure 2 through Figure 5).

• Minimum C

• ESR range: see Figure 2 through Figure 5

It is critical that both the minimum capacitance and ESR requirement be met over the entire operating

temperature range. Depending on the type of capacitor used, both of these parameters can vary significantly with

temperature (see capacitor characteristics section).

Figure 2. 5-V/3.3-

µF ESR Curves

Figure 3. 5-V/10-

µF ESR Curves

Figure 4. 3-V/3.3-

µF ESR Curves

Figure 5. 3-V/10-

µF ESR Curves

6

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