RPG

COUT

1 µF

CIN

1 µF

IN

OUT

EN

PG

GND

VOUT

VIN

LP3988

OFF

ON

VOUT OK

ERROR

VPG

VEN

LP3988

SNVS161E – OCTOBER 2001 – REVISED OCTOBER 2015

www.ti.com

9 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.

9.1 Application Information

The LP3988 voltage regulator offers the benefit of ultra-low-dropout voltage, low noise, very low standby current,

and miniaturized surface-mount packaging. The LP3988 is designed for continuous, or sporadic (power backup),

battery-operated applications where very low standby current is critical to extending system battery life.

9.2 Typical Application

Figure 12. LP3988 Typical Application

9.2.1 Design Requirements

For typical CMOS voltage regulator applications, use the parameters listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Minimum input voltage

2.5 V

Output voltages

various

Output current

150 mA

9.2.2 Detailed Design Procedure

9.2.2.1 External Capacitors

Like any low-dropout regulator, the LP3988 requires external capacitors for regulator stability. The LP3988 is

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

capacitors must be correctly selected for good performance.

9.2.2.2 Input Capacitor

An input capacitance of at least 1

μF is required between the LP3988 IN pin and ground (the amount of the

capacitance may be increased without limit). This capacitor must be located a distance of not more than 1cm

from the input pin and returned to a clean analog ground. Any good quality ceramic, tantalum, or film capacitor

may be used at the input

12

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