LM25007_08 NSC [National Semiconductor], LM25007_08 Datasheet

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LM25007_08

Manufacturer Part Number
LM25007_08
Description
42V, 0.5A Step-Down Switching Regulator
Manufacturer
NSC [National Semiconductor]
Datasheet
© 2008 National Semiconductor Corporation
LM25007
42V, 0.5A Step-Down Switching Regulator
General Description
The LM25007 is a monolithic step-down switching regulator
featuring all of the functions needed to implement a low cost,
efficient, power supply. Capable of driving a 0.5Amp load over
a 9V-42V input voltage range, this device is easy to apply and
is provided in the small MSOP-8 and the thermally enhanced
LLP-8 packages. Ultra-fast transient response is achieved
through the use of a constant on-time architecture with Vin
feed forward. This feature provides an almost constant oper-
ating frequency over load and input voltage variations. The
operating frequency can be adjusted with a single resistor.
This architecture is easy to use and tolerant of component
selection. An intelligent current limit is implemented in the
LM25007 with forced off time that is inversely proportional to
Vout thus ensuring recovery from fault conditions. The output
voltage may be set from 2.5V to >30V. To improve efficiency
in light load applications, the Vcc pin can be connected to an
external voltage source to eliminate the drop through the in-
ternal regulator. Additional features include: thermal shut-
down, Vcc under-voltage lockout, gate drive under-voltage
lockout, and max duty cycle limiter.
Basic Step-Down Regulator
201655
Features
Typical Applications
Package
Integrated 0.74 ohm N-Channel MOSFET switch
Guaranteed 0.5Amp output current
Ultra-Fast Transient Response
Up to 800kHz operation
No control loop compensation required
Vin feed forward provides constant operating frequency
2% accurate 2.5V feedback from -40°C to 125°C
Highly efficient operation
Intelligent current limit protection
External shutdown control
Thermal shutdown
MSOP-8 and thermally enhanced LLP packages
12VDC and 24VDC distributed rail systems
24VAC systems
Automotive body electronics and telematics
Industrial systems
HB-LED constant current source
MSOP - 8
LLP - 8 (4mm x 4mm)
20165513
February 5, 2008
www.national.com

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LM25007_08 Summary of contents

Page 1

LM25007 42V, 0.5A Step-Down Switching Regulator General Description The LM25007 is a monolithic step-down switching regulator featuring all of the functions needed to implement a low cost, efficient, power supply. Capable of driving a 0.5Amp load over a 9V-42V input ...

Page 2

Connection Diagram Ordering Information Order Number LM25007MM LM25007MMX LM25007SD LM25007SDX Pin Descriptions Pin Name 1 SW Switching Node 2 BST Boost Boot–strap capacitor input 3 RCL Current Limit OFF time programming pin 4 RTN Circuit Ground 5 FB Feedback Signal ...

Page 3

Typical Application Circuit and Block Diagram 3 20165501 www.national.com ...

Page 4

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN to RTN BST to RTN SW to RTN (Steady State) ESD Rating (Note 5) Human Body Model Electrical ...

Page 5

Symbol Parameter Minimum Off Time Minimum Off Timer Regulation and OV Comparators FB Reference Threshold FB Over-Voltage Threshold FB Bias Current Thermal Shutdown Tsd Thermal Shutdown Temp. Thermal Shutdown Hysteresis Thermal Resistance θ Junction to Ambient JA Note 1: Absolute ...

Page 6

Typical Performance Characteristics Operational Waveforms LM25007 Operation 10V 20V, I OUT IN CH1: Switch Node, CH2: V (AC), CH4: Inductor Current OUT LM25007 10V Output Efficiency 100k, 200k, 300k ...

Page 7

Detailed Operating Description The LM25007 is a monolithic step-down switching regulator featuring all of the functions needed to implement low cost, efficient, power supply. Capable of driving a 0.5Amp load over a 9-42V input voltage range, this device is easy ...

Page 8

FIGURE 1. Low Ripple Output Configuration FIGURE 2. Self Biased Configuration 8 20165505 20165506 ...

Page 9

Over-Voltage Comparator The over-voltage comparator is provided to protect the output from overvoltage conditions due to sudden input line voltage changes or output loading changes. The over-voltage com- parator monitors the FB pin versus an internal 2.875V refer- ence. If ...

Page 10

The reverse voltage rating of the re-circulating diode must be greater than the maximum line input voltage. Thermal Protection Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event the maximum junction temper- ature is ...

Page 11

Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead MSOP Package NS Package Number MUA08A 8-Lead LLP Package NS Package Number SDC08A 11 www.national.com ...

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