LP2983 Datasheet, PDF (14/25 Pages) National Semiconductor (TI) – Micropower 150 mA Voltage Regulator in SOT-23 Package For Output Voltages 1.2V Designed for Use with Very Low ESR Output Capacitors

LP2983
SNVS170D – OCTOBER 2001 – REVISED APRIL 2016
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8.2.2 Detailed Design Procedure
8.2.2.1 External Capacitors
Like any low-dropout regulator, the LP2983 requires external capacitors for regulator stability. These capacitors
must be correctly selected for good performance.
8.2.2.1.1 Input Capacitor
An input capacitor whose capacitance is ≥ 1 µF is required between the LP2983 input and ground (the amount of
capacitance may be increased without limit).
This capacitor must be located a distance of not more than 1 cm 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.
NOTE
Tantalum capacitors can suffer catastrophic failure due to surge current when connected
to a low-impedance source of power (like a battery or very large capacitor). If a tantalum
capacitor is used at the input, it must be ensured by the manufacturer to have a surge
current rating sufficient for the application.
There are no requirements for ESR on the input capacitor, but tolerance and temperature coefficient must be
considered when selecting the capacitor to ensure the capacitance is ≥ 1 µF over the entire operating
temperature range.
8.2.2.1.2 Output Capacitors
The LP2983 is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the
regulator to be stable across the entire range of output current with an output capacitor whose ESR is as low as
0 Ω.
The ceramic output capacitor must be connected between the OUT pin (device pin 5) and the ESR pin (device
pin 4) (see Figure 24).
Figure 24. Ceramic to ESR Pin (C_OUT = 2.2 µF)
The LP2983 requires a minimum of 2.2 µF on the output (output capacitor size can be increased without limit).
It is important to remember that capacitor tolerance and variation with temperature must be taken into
consideration when selecting an output capacitor so that the minimum required amount of output capacitance is
provided over the full operating temperature range. Note that ceramic capacitors can exhibit large changes in
capacitance with temperature (see Capacitor Characteristics).
The output capacitor must be located not more than 1 cm from the output pin and returned to a clean analog
ground via the ESR pin.
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