ON/OFF

ON/OFF

GND

IN

BYPASS

OUT

OFF

ON

2.2 µF (5-V device)

4.7 µF (3-V and 3.3-V devices)

0.01 µF

1 µF

1

Ÿ

16

LP2982

SNVS128K – MARCH 2000 – REVISED JUNE 2016

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8.2.2.1.1

Input Capacitor

An input capacitor with a value

≥ 1 μF is required with the LP2982 (amount of capacitance can be increased

without limit).

This capacitor must be located a distance of not more than 0.5 inches from the input pin of the LP2982 and

returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor.

8.2.2.1.2

Output Capacitor

The output capacitor must meet both the requirement for minimum amount of capacitance and equivalent series

resistance (ESR) value. Curves are provided which show the allowable ESR range as a function of load current

for various output voltages and capacitor values (refer to Figure 40 and Figure 41).

NOTE

Important: The output capacitor must maintain its ESR in the stable region over the full

operating temperature range to ensure stability. Also, capacitor tolerance and variation

with temperature must be considered to ensure the minimum amount of capacitance is

provided at all times.

This capacitor must be located not more than 0.5 inches from the OUT pin of the LP2982 and returned to a clean

analog ground.

8.2.2.1.3

Bypass Capacitor

The 0.01-μF capacitor connected to the bypass pin to reduce noise must have very low leakage.

The current flowing out of the bypass pin comes from the bandgap reference, which is used to set the output

voltage.

This capacitor leakage current causes the output voltage to decline by an amount proportional to the current.

Typical values are

−0.015%/nA at −40°C, −0.021%/nA at 25°C, and −0.035%/nA at 125°C.

This data is valid up to a maximum leakage current of about 500 nA, beyond which the bandgap is so severely

loaded that it can not function.

Care must be taken to ensure that the capacitor selected does not have excessive leakage current over the

operating temperature range of the application.

A high-quality ceramic capacitor which uses either NPO or COG type dielectric material typically has very low

leakage. Small surface mount polypropylene or polycarbonate film capacitors also have extremely low leakage,

but are slightly larger than ceramics.