LP2987, LP2988
SNVS004J –MARCH 1999–REVISED APRIL 2013
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APPLICATION HINTS
WSON Package Devices
The LP2987/LP2988 is offered in the 8 lead WSON surface mount package to allow for increased power
dissipation compared to the SOIC-8 and the VSSOP-8. For details on thermal performance as well as mounting
and soldering specifications, refer to Application Note AN-1187 (literature number SNOA401).
EXTERNAL CAPACITORS
As with any low-dropout regulator, external capacitors are required to assure stability. These capacitors must be
correctly selected for proper performance.
INPUT CAPACITOR: An input capacitor (≥ 2.2 µF) is required between the LP2987/8 input and ground (amount
of capacitance may be increased without limit).
This capacitor must be located 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.
OUTPUT CAPACITOR: The output capacitor must meet the requirement for minimum amount of capacitance
and also have an appropriate E.S.R. (equivalent series resistance) value.
Curves are provided which show the allowable ESR range as a function of load current for 3V and 5V outputs.
Figure 44. ESR Curves For 5V Output
Figure 45. ESR Curves For 3V Output
IMPORTANT: The output capacitor must maintain its ESR in the stable region over the full operating
temperature range of the application to assure stability.
The minimum required amount of output capacitance is 4.7 µF. 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. A good Tantalum capacitor will show very little variation with
temperature, but a ceramic may not be as good (see next section).
The output capacitor should be located not more than 0.5” from the output pin and returned to a clean analog
ground.
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