IN

OUT

GND

5 V OUT

1 µF

2.2 µF

LOAD

13

LP2954, LP2954A

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SNVS096E – JUNE 1999 – REVISED JULY 2016

Product Folder Links: LP2954 LP2954A

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Copyright © 1999–2016, Texas Instruments Incorporated

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LP2954-N is a linear voltage regulator operating from 2.3 V to 30 V on the input and regulated output

voltage of 5 V with typical 0.5% accuracy (LP2954AI) and 250 mA maximum output current. For linear voltage

dropout LDO. Successfully implementing an LDO in an application depends on the application requirements. If

the requirements are simply input voltage and output voltage, compliance specifications (such as internal power

dissipation or stability) must be verified to ensure a solid design. If timing, start-up, noise, PSRR, or any other

transient specification is required, the design becomes more challenging.

8.2 Typical Application

Figure 18. LP2954 Typical Application

8.2.1 Design Requirements

For typical LDO applications, use the parameters listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage

2.5 V to 30 V

Output voltage

1.23 V to 29 V

Output current

250 mA (maximum)

RMS noise, 10 Hz to100 kHz

8.2.2 Detailed Design Procedure

8.2.2.1 External Capacitors

A 2.2 μF (or greater) capacitor is required between the OUT pin and GND to assure stability (refer to Figure 20).

Without this capacitor, the device may oscillate. Most types of tantalum or aluminum electrolytic capacitors work

here. Film-type capacitors work, but are more expensive. Many aluminum electrolytics contain electrolytes which

freeze at

−30°C, which requires the use of solid tantalums below −25°C. The important parameters of the

capacitor are an equivalent series resistance (ESR) of about 5 Ω or less and a resonant frequency above 500

kHz (the ESR may increase by a factor of 20 or 30 as the temperature is reduced from 25°C to

−30°C). The

value of this capacitor may be increased without limit. At lower values of output current, less output capacitance

is required for stability. The capacitor can be reduced to 0.68 μF for currents below 10 mA or 0.22 μF for currents

below 1 mA.