LP2985_15 Datasheet, PDF (11/29 Pages) Texas Instruments – 150-mA Low-noise Low-dropout Regulator With Shutdown

LP2985
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7 Detailed Description
SLVS522O – JULY 2004 – REVISED JANUARY 2015
7.1 Overview
The LP2985 family of fixed-output, low-dropout regulators offers exceptional, cost-effective performance for both
portable and nonportable applications. Available in voltages of 1.8 V, 2.5 V, 2.8 V, 2.9 V, 3 V, 3.1 V, 3.3 V, 5 V,
and 10 V, the family has an output tolerance of 1% for the A version (1.5% for the non-A version) and is capable
of delivering 150-mA continuous load current. Standard regulator features, such as overcurrent and
overtemperature protection, are included.
7.2 Functional Block Diagram
V_IN
ON/OFF
V_REF
1.23 V
−
+
BYPASS
Overcurrent/
Overtemperature
Protection
V_OUT
7.3 Feature Description
The LP2985 has a host of features that makes the regulator an ideal candidate for a variety of portable
applications:
• Low dropout: A PNP pass element allows a typical dropout of 280 mV at 150-mA load current and 7 mV at 1-
mA load.
• Low quiescent current: The use of a vertical PNP process allows for quiescent currents that are considerably
lower than those associated with traditional lateral PNP regulators.
• Shutdown: A shutdown feature is available, allowing the regulator to consume only 0.01 μA when the
ON/OFF pin is pulled low.
• Low-ESR-capacitor friendly: The regulator is stable with low-ESR capacitors, allowing the use of small,
inexpensive, ceramic capacitors in cost-sensitive applications.
• Low noise: A BYPASS pin allows for low-noise operation, with a typical output noise of 30 μV_RMS, with the
use of a 10-nF bypass capacitor.
• Small packaging: For the most space-constrained needs, the regulator is available in the SOT-23 package.
7.4 Device Functional Modes
7.4.1 Normal Operation
In normal operation, the device will output a fixed voltage corresponding with the orderable part number. The
device can deliver 150 mA of continuous load current.
7.4.2 Shutdown Mode
Set the ON/OFF pin low to shut down the device when V_IN is still present. If a shutdown mode is not needed, tie
the pin to V_IN. For proper operation, do not leave ON/OFF unconnected, and apply a signal with a slew rate of
≥40 mV/μs.
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