Datasheet

LP2989LV

www.ti.com

SNVS086J –MAY 2000–REVISED APRIL 2013

APPLICATION HINTS

WSON Package Devices

The LP2989LV is offered in the 8 lead WSON surface mount package to allow for increased power dissipation

compared to the SOIC-8 and VSSOP. For details on thermal performance as well as mounting and soldering

specifications, refer to Application Note AN-1187 (SNOA401Q).

For output voltages ≥ 2V, see LP2989 data sheet.

External Capacitors

Like any low-dropout regulator, the LP2989LV requires external capacitors for regulator stability.These capacitors

must be correctly selected for good performance.

Input Capacitor: An input capacitor whose capacitance is at least 2.2 µF is required between the LP2989LV

input and ground (the amount of capacitance may be increased without limit).

Characterization testing performed on the LP2989LV has shown that if the amount of actual input capacitance

drops below about 1.5 µF, an unstable operating condition may result. Therefore, the next larger standard size

(2.2 µF) is specified as the minimum required input capacitance. Capacitor tolerance and temperature variation

must be considered when selecting a capacitor (see Capacitor Characteristics section) to assure the minimum

requirement of 1.5 µF is met over all operating conditions.

The input capacitor must be located at a distance of not more than 0.5" from the input pin and returned to a

clean analog ground. Any good quality ceramic or tantalum may be used for this capacitor, assuming the

minimum capacitance requirement is met.

Output Capacitor: The LP2989LV requires a ceramic output capacitor whose size is at least 10 µF. The actual

amount of capacitance on the output must never drop below about 7 µF or unstable operation may result. For

this reason, capacitance tolerance and temperature characteristics must be considered when selecting an output

capacitor

The LP2989LV 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

4 mΩ. It may also be possible to use Tantalum or film capacitors at the output, but these are not as attractive for

reasons of size and cost (see Capacitor Characteristics section).

The output capacitor must meet the requirement for minimum amount of capacitance and also have an ESR

(equivalent series resistance) value which is within the stable range. Curves are provided which show the stable

ESR range as a function of load current (see Figure 14).

Figure 14. Stable Region For Output Capacitor ESR

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

temperature range of the application to assure stability.

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. (See Capacitor Characteristics section.)

Product Folder Links: LP2989LV