LP3871_15 Datasheet, PDF (11/26 Pages) Texas Instruments – LP387x 0.8-A Fast Ultra-Low-Dropout Linear Regulators

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8 Application and Implementation
LP3871, LP3874
SNVS225H – FEBRUARY 2003 – 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 must
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LP3871 and LP3874 devices are linear regulators designed to provide high load current of up to 0.8 A, low
dropout voltage, and low quiescent current in shutdown mode.
8.1.1 Reverse Current Path
The internal MOSFET in LP3871 and LP3874 has an inherent parasitic diode. During normal operation, the input
voltage is higher than the output voltage and the parasitic diode is reverse biased. However, if the output is
pulled above the input in an application, then current flows from the output to the input as the parasitic diode gets
forward biased. The output can be pulled above the input as long as the current in the parasitic diode is limited to
200-mA continuous and 1-A peak.
8.1.2 Turnon Characteristics for Output Voltages Programmed To 2 V or Below
As V_IN increases during start-up, the regulator output will track the input until V_IN reaches the minimum operating
voltage (typically about 2.5 V). For output voltages programmed to 2 V or below, the regulator output may
momentarily exceed its programmed output voltage during start-up. Outputs programmed to voltages above 2 V
are not affected by this behavior.
8.2 Typical Applications
*SD and ERROR pins must be pulled high through a 10-kΩ pullup resistor. Connect the ERROR pin to ground if this
function is not used.
Figure 11. LP3871 Typical Application
*SD must be pulled high through a 10-kΩ pullup resistor.
Figure 12. LP3874 Typical Application
Copyright © 2003–2015, Texas Instruments Incorporated
Product Folder Links: LP3871 LP3874
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