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LP5910

SNVSA91E – SEPTEMBER 2015 – REVISED JULY 2017

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8.2.2.2 External Capacitors

Like most low-dropout regulators, the LP5910 requires external capacitors for regulator stability. The device is

specifically designed for portable applications requiring minimum board space and smallest components. These

capacitors must be correctly selected for good performance.

8.2.2.3 Input Capacitor

An input capacitor is required for stability. It is recommended that a 1-µF capacitor be connected from the

LP5910 IN pin to ground. (This capacitance value may be increased without limit.) The input capacitor must be

located a distance of not more than 1 cm from the IN pin and returned to a clean analog ground. Any good

quality ceramic, tantalum, or film capacitor may be used at the input.

NOTE

Tantalum capacitors can suffer catastrophic failures due to surge current when connected

to a low-impedance source of power (like a battery or a very large capacitor). If a tantalum

capacitor is used at the input, it must be guaranteed by the manufacturer to have a surge

current rating sufficient for the application. There are no requirements for the equivalent

series resistance (ESR) on the input capacitor, but tolerance and temperature coefficient

must be considered when selecting the capacitor to ensure the capacitance remains 1 µF

±30% over the entire operating temperature range.

8.2.2.4 Output Capacitor

For capacitance values in the range of 1 µF to 4.7 µF, ceramic capacitors are the smallest, least expensive and

have the lowest ESR values, thus making them best for eliminating high frequency noise. The ESR of a typical 1-

µF ceramic capacitor is in the range of 20 m

Ω to 40 mΩ, which easily meets the ESR requirement for stability for

the LP5910. The temperature performance of ceramic capacitors varies by type. Most large value ceramic

capacitors (

≥ 2.2 µF) are manufactured with Z5U or Y5V temperature characteristics, which results in the

capacitance dropping by more than 50% as the temperature goes from 25°C to 85°C.

A better choice for temperature coefficient in a ceramic capacitor is X7R. This type of capacitor is the most stable

and holds the capacitance within ±15% over the temperature range. Tantalum capacitors are less desirable than

ceramic for use as output capacitors because they are more expensive when comparing equivalent capacitance

and voltage ratings in the 1-µF to 4.7-µF range.

8.2.2.5 Capacitor Characteristics

The LP5910 is designed to work with ceramic capacitors on the input and output to take advantage of the

benefits they offer. For capacitance values in the range of 1 µF to 10 µF, ceramic capacitors are the smallest,

least expensive and have the lowest ESR values, thus making them best for eliminating high frequency noise.

The ESR of a typical 1-µF ceramic capacitor is in the range of 20 mΩ to 40 mΩ, which easily meets the ESR

requirement for stability for the LP5910.

A better choice for temperature coefficient in a ceramic capacitor is X7R. This type of capacitor is the most stable

and holds the capacitance within ±15% over the temperature range. Tantalum capacitors are less desirable than

ceramic for use as output capacitors because they are more expensive when comparing equivalent capacitance

and voltage ratings in the 1-µF to 10-µF range.