LP38511-1.8 NSC [National Semiconductor], LP38511-1.8 Datasheet

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LP38511-1.8

Manufacturer Part Number
LP38511-1.8
Description
800 mA Fast-Transient Response Low-Dropout Linear Voltage Regulator with Error Flag
Manufacturer
NSC [National Semiconductor]
Datasheet
© 2008 National Semiconductor Corporation
LP38511-1.8
800 mA Fast-Transient Response Low-Dropout Linear
Voltage Regulator with Error Flag
General Description
The LP38511-1.8 Fast-Transient Response Low-Dropout
Voltage Regulator offers the highest-performance in meeting
AC and DC accuracy requirements for powering Digital
Cores. The LP38511-1.8 uses a proprietary control loop that
enables extremely fast response to change in line conditions
and load demands. Output Voltage DC accuracy is guaran-
teed at ±2.5% over line, load and full temperature range from
-40°C to +125°C. The LP38511-1.8 is designed for inputs
from the 2.5V, 3.3V, and 5.0V rail, is stable with 10uF ceramic
capacitors, and has a fixed 1.8V output. An Error Flag feature
monitors the output voltage and notifies the system processor
when the output voltage falls more than 15% below the nom-
inal value. The LP38511-1.8 provides excellent transient per-
formance to meet the demand of high performance digital
core ASICs, DSPs, and FPGAs found in highly-intensive ap-
plications such as servers, routers/switches, and base sta-
tions.
Typical Application Circuit
201829
Features
Applications
2.25V to 5.5V Input Voltage Range
1.8V Fixed Output Voltage
800 mA Output Load Current
+/- 2.5% V
Temperature Range from -40°C to +125°C
Stable with tiny 10 µF ceramic capacitors
0.20% Output Voltage Load Regulation from 10 mA to 800
mA
Enable pin
Error Flag Indicates Status of Output Voltage
1 µA of Quiescent current in Shutdown
40dB of PSRR at 100 kHz
Over-Temperature and Over-Current Protection
TO263 and TO-263 THIN Surface Mount Packages
Digital Core ASICs, FPGAs, and DSPs
Servers
Routers and Switches
Base Stations
Storage Area Networks
DDR2 Memory
OUT
Accuracy over Line, Load, and Full-
20182901
www.national.com
May 14, 2008

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LP38511-1.8 Summary of contents

Page 1

... Output Voltage DC accuracy is guaran- teed at ±2.5% over line, load and full temperature range from -40°C to +125°C. The LP38511-1.8 is designed for inputs from the 2.5V, 3.3V, and 5.0V rail, is stable with 10uF ceramic capacitors, and has a fixed 1.8V output. An Error Flag feature ...

Page 2

... The TO-263 TAB, and the TO-263 THIN DAP, is used as a thermal connection to remove heat from the device to an external heatsink. The TAB/DAP is internally connected to device pin 3, and is electrical ground connection. 2 Package Marking Supplied As: LP38511TJ-1.8 Rail LP38511TJ-1.8 Tape and Reel LP38511TS-1.8 Rail LP38511TS-1.8 Tape and Reel 20182905 Top View ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range Peak Reflow Temperature (Note 3) PSOP-8 TO-263 ESD Rating (Note 2) Power Dissipation(Note 4) Input Pin ...

Page 4

... Note 7: The line and load regulation specification contains only the typical number. However, the limits for line and load regulation are included in the output voltage tolerance specification. Note 8: Dropout voltage is defined as the minimum input to output differential voltage at which the output drops 2% below the nominal value. For the LP38511-1.8, the minimum V operating voltage is the limiting factor ...

Page 5

Typical Performance Characteristics µ µ mA. IN OUT OUT V vs Temperature OUT Ground Pin Current (I GND Ground Pin Current Temperature, V GND Unless otherwise specified: T 20182911 ...

Page 6

OUT EN V ERROR Flag Threshold vs Temperature OUT Load regulation vs Temperature www.national.com (t ) d(ON) 20182932 20182917 20182920 OUT EN d(OFF) 20182930 ERROR Flag Low vs Temperature 20182918 Line ...

Page 7

Current Limit vs Temperature Load Transient 800 µF Ceramic + 100 µF Aluminum OUT Load Transient, 250 mA to 800 μF Ceramic + 100 μF Aluminum C OUT Load Transient, ...

Page 8

PSRR, 10Hz to 1MHz www.national.com 20182929 8 Noise 20182931 ...

Page 9

... A Schottky diode is recommended for this protective clamp. SHORT-CIRCUIT PROTECTION The LP38511 is short circuit protected, and in the event of a peak over-current condition the short-circuit control loop will rapidly drive the output PMOS pass element off. Once the power pass element shuts down, the control loop will rapidly ...

Page 10

... ERROR Flag pin is immediately forced low. ERROR FLAG OPERATION EN(ON) thresh- When the LP38511 Enable pin is high, the ERROR Flag pin EN(OFF) will produce a logic low signal when the output drops by more than 15% from the nominal output voltage. The drop in output voltage may be due to low input voltage, current limiting, or thermal limiting ...

Page 11

FIGURE 2. ERROR Flag Operation, biased from V POWER DISSIPATION/HEATSINKING A heatsink may be required depending on the maximum pow- er dissipation (P ), maximum D(MAX) temperature ( the application, and the thermal re- A(MAX) sistance (θ ) ...

Page 12

Physical Dimensions TO-263, Molded, 5 Lead, 0.067in (1.7mm) Pitch, Surface Mount Package TO-263 THIN, Molded, 5 Lead, 1.7mm Pitch, Surface Mount Package www.national.com inches (millimeters) unless otherwise noted NS Package Number TS5B NS Package Number TJ5A 12 ...

Page 13

Notes 13 www.national.com ...

Page 14

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