LP38502-ADJ Datasheet, PDF (13/27 Pages) Texas Instruments – LP3850x-ADJ, LP3850xA-ADJ 1.5-A Flexcap Low-Dropout Linear Regulatorfor 2.7-V to 5.5-V Inputs

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8 Application and Implementation
LP38500-ADJ, LP38502-ADJ
SNVS539G – NOVEMBER 2007 – REVISED JUNE 2015
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.
8.1 Application Information
The LP38500-ADJ and LP38502-ADJ devices can provide 1.5-A output current with 2.7-V to 5.5-V input voltage.
These ultra-low-dropout linear regulators respond very quickly to step changes in load, making them suitable for
low-voltage microprocessor applications. Input and output capacitors of at least 10 µF are required.
8.2 Typical Applications
Figure 17. Typical Circuit (LP38500)
Figure 18. Typical Circuit (LP38502)
8.2.1 Design Requirements
For LP3850x-ADJ typical applications, use the parameters listed in Table 1 as the input parameters.
DESIGN PARAMETERS
Input voltage
Output voltage
Output current
Input capacitor
Output capacitor
Table 1. Design Parameters
VALUE
2.7 V to 5.5 V
0.6 V to 5 V (adjustable)
1.5 A (maximum)
10 µF (minimum)
10 uF (minimum)
8.2.2 Detailed Design Procedure
8.2.2.1 External Capacitors
The LP38500-ADJ and LP38502-ADJ require that at least 10-µF (±20%) capacitors be used at the input and
output pins located within one cm of the device. Larger capacitors may be used without limit on size for both C_IN
and C_OUT. Capacitor tolerances such as temperature variation and voltage loading effects must be considered
when selecting capacitors to ensure that they will provide the minimum required amount of capacitance under all
operating conditions for the application.
In general, ceramic capacitors are best for noise bypassing and transient response because of their ultra low
ESR. It must be noted that if ceramics are used, only the types with X5R or X7R dielectric ratings should be used
(never Z5U or Y5F). Capacitors which have the Z5U or Y5F characteristics will see a drop in capacitance of as
much as 50% if their temperature increases from 25°C to 85°C. In addition, the capacitance drops significantly
with applied voltage: a typical Z5U or Y5F capacitor can lose as much as 60% of its rated capacitance if only half
of the rated voltage is applied to it. For these reasons, only X5R and X7R ceramics should be used.
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