LP2980-N_15_15 Datasheet, PDF (17/30 Pages) Texas Instruments – LP2980-N Micropower 50-mA Ultra Low-Dropout Regulator in SOT-23 Package

www.ti.com
LP2980-N
SNOS733O – APRIL 2000 – REVISED JUNE 2015
It is also important that the turn-on and turn-off voltage signals applied to the ON/OFF input have a slew rate that
is greater than 40 mV/μs.
NOTE
The regulator shutdown function will not operate correctly if a slow-moving signal is used
to drive the ON/OFF input.
8.2.2.4 Increasing Output Current
The LP2980-N can be used to control higher-current regulators, by adding an external PNP pass transistor. With
the PNP transistors shown in Figure 36, the output current can be as high as 400 mA, as long as the input
voltage is held within the Safe Operation Boundary Curves shown below in Figure 37.
To ensure regulation, the minimum input voltage of this regulator is 6 V. This headroom is the sum of the V_BE of
the external transistor and the dropout voltage of the LP2980-N.
Figure 36. 5-V and 400-mA Regulator
Notes:
Note A: Drive this input with a logic signal (see ON/OFF Input Operation). If the shutdown function is not to be
used, tie the ON/OFF pin directly to the IN pin.
Note B: Recommended devices (other PNP transistors can be used if the current gain and voltage ratings are
similar).
Note C: Capacitor is required for regulator stability. Minimum size is shown, and may be increased without limit.
Note D: Increasing the output capacitance improves transient response and increases phase margin.
Note E: Maximum safe input voltage and load current are limited by power dissipation in the PNP pass transistor
and the maximum ambient temperature for the specific application. If a TO-92 transistor such as the MPS2907A
is used, the thermal resistance from junction-to-ambient is 180°C/W in still air.
Assuming a maximum allowable junction temperature of 150°C for the MPS2907A device, the following curves
show the maximum V_IN and I_L values that may be safely used for several ambient temperatures.
Copyright © 2000–2015, Texas Instruments Incorporated
Product Folder Links: LP2980-N
Submit Documentation Feedback
17