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National Semiconductor LP38691 LP38693 User's Manual and Specifications

Summary

These low dropout CMOS linear regulators provide highly stable power management solutions with excellent precision and a wide operating temperature range. Ideal for applications requiring reliable power conversion, these components feature extremely low dropout voltage and are optimized for use with ceramic output capacitors. The accompanying documentation details the electrical specifications, pin descriptions (V, GND, OUT, EN), connection diagrams, and ordering information crucial for design engineers. They are perfect for portable instrumentation, notebook computers, battery-powered devices, and hard disk drives needing high reliability power supplies.

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/L ro t C in r R la to rs ta le ith ra ic tp t C ito rs

October 24, 2008

LP38691/LP38693 500m A Low Dropout CMOS Linear Regulators Stable with Ceramic Output Capacitors General Description Features The LP38691/3 low dropout CMOS linear regulators provide 2.0% output accuracy (25°C) tight output tolerance (2.0% typical), extremely low dropout

Low dropout voltage: 250 m V @ 500m A (typ, 5V out)

voltage (250 m V @ 500m A load current, VOUT = 5V), and ex-

Wide input voltage range (2.7V to 10V)

cellent AC performance utilizing ultra low ESR ceramic output

Precision (trimmed) bandgap reference

capacitors.

Guaranteed specs for -40°C to +125°C

The low thermal resistance of the LLP, SOT-223 and T0-252

packages allow the full operating current to be used even in 1µA off-state quiescent current

high ambient temperature environments. Thermal overload protection The use of a PMOS power transistor means that no DC base Foldback current limiting drive current is required to bias it allowing ground pin current

T0-252, SOT-223 and 6-Lead LLP packages

to remain below 100 µA regardless of load current, input volt-

Enable pin (LP38693)

age, or operating temperature. Dropout Voltage: 250 m V (typ) @ 500m A (typ. 5V out).

Applications

Ground Pin Current: 55 µA (typ) at full load.

Hard Disk Drives

Precision Output Voltage: 2.0% (25°C) accuracy.

Notebook Computers Battery Powered Devices Portable Instrumentation

Typical Application Circuits

Note: * Minimum value required for stability. **LLP package devices only.

© 2008 National Semiconductor Corporation www.national.com

Page Summary Contents For National Semiconductor LP38691 LP38693 User's Manual and Specifications

Page 1 /L ro t C in r R la to rs ta le ith ra ic tp t C ito rs October 24, 2008 LP38691/LP38693 500m A Low Dropout CMOS Linear Regulators Stable with Ceramic Output Capacitors General Description Features Th...
Page 2 Connection Diagrams TO-252, Top View LP38691DT-X.X SOT-223, Top View LP38693MP-X.X 6-Lead LLP, Bottom View 6-Lead LLP, Bottom View LP38691SD-X.X LP38693SD-X.X Pin Descriptions Pin Description VIN This...
Page 3 Ordering Information Order Number Package Marking Package Type Package Drawing Supplied As LP38691SD-1.8 L118B 6-Lead LLP SDE06A 1000 Units Tape and Reel LP38691SD-2.5 L119B 6-Lead LLP SDE06A 1000 Uni...
Page 4 V(max) All pins (with respect to GND) -0.3V to 12V Absolute Maximum Ratings (Note 1) IOUT Internally Limited If Military/Aerospace specified devices are required, Junction Temperature −40°C to +150°C ...
Page 5 Typ (Note Symbol Parameter Conditions Min Max Units en Output Noise BW = 10Hz to 10k Hz VO = 3.3V VO (LEAK) Output Leakage Current VO = VO(NOM) + 1V @ 10VIN 0.5 µA VEN Enable Voltage (LP38693 Only) Ou...
Page 6 Block Diagrams FIGURE 1. LP38691 Functional Diagram (LLP) FIGURE 2. LP38691 Functional Diagram (TO-252) www.national.com
Page 7 FIGURE 3. LP38693 Functional Diagram (LLP) FIGURE 4. LP38693 Functional Diagram (SOT-223) www.national.com
Page 8 Typical Performance Characteristics Unless otherwise specified: TJ = 25°C, CIN = COUT = 10 µF, Enable pin is tied to VIN (LP38693 only), VOUT = 1.8V, VIN = VOUT +1V, IL = 10m A. Noise vs Frequency Noi...
Page 9 /L Line Transient Response Line Transient Response Line Transient Response Load Transient Response Load Transient Response VOUT vs Temperature (5.0V) www.national.com
Page 10 VOUT vs Temperature (3.3V) VOUT vs Temperature (2.5V) VOUT vs Temperature (1.8V) VOUT vs VIN (1.8V) Enable Voltage vs Temperature Load Regulation vs Temperature www.national.com
Page 11 /L Line Regulation vs Temperature MIN VIN vs IOUT Dropout Voltage vs IOUT www.national.com
Page 12 capacitance value that varies less than 10-15% across the full /L Application Hints temperature range of -40°C to +125°C. ESR will vary only about 2X going from the high to low temperature limits. EXT...
Page 13 a 1Hz bandwidth). This type of noise is usually plotted on a /L The primary source of noise in low-dropout regulators is the curve as a function of frequency. Total Output Noise or internal reference....
Page 14 Physical Dimensions inches (millimeters) unless otherwise noted 6-lead, LLP Package NS Package Number SDE06A TO-252 Package NS Package Number TD03B www.national.com
Page 15 SOT-223 Package NS Package Number MP05A www.national.com
Page 16 /L ro in la to rs ta le it ra ic tp it rs Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.na...

Manual Details

Brand National
Pages 16
File Size 363.63 KB
Published June 17, 2026
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Frequently Asked Questions

What is the typical low dropout voltage rating?

It provides a typical low dropout of 250 mV @ 500mA.

Are ceramic capacitors necessary for stable function?

Yes, the regulator requires ceramic output capacitors to achieve stability.

How can I eliminate error due to voltage drops in long traces?

Utilize the Sense pin (SNS) by connecting it and tying it directly to the OUT pin.

What is the guaranteed operating temperature range?

The device is rated for operation from -40°C up to +125°C.