LM20145 - 5A, PowerWise Adjustable Frequency Synchronous Buck Regulator

Datasheet	Packaging	Samples & Pricing	Eval. Boards	Reliability	Design Tools	Reference Designs	Application Notes	Knowledge Base

Features

•	Input voltage range 2.95V to 5.5V
•	Accurate current limit minimizes inductor size
•	97% peak efficiency
•	Adjustable switching frequency (250 kHz to 750 kHz)
•	32 mΩ integrated FET switches
•	Starts up into pre-biased loads
•	Output voltage tracking
•	Peak current mode control
•	Adjustable output voltage down to 0.8V
•	Adjustable Soft-Start with external capacitor
•	Precision enable pin with hysteresis
•	Integrated OVP, UVLO, power good and thermal shutdown
•	eTSSOP-16 exposed pad package

General Description

The LM20145 is a full featured adjustable frequency synchronous buck regulator capable of delivering up to 5A of continuous output current. More...

Applications

•	Simple to design, high efficiency point of load regulation from a 5V or 3.3V bus
•	High Performance DSPs, FPGAs, ASICs and microprocessors
•	Broadband, Networking and Optical Communications Infrastructure

Typical Application

click for larger image

Parameters Values

Output Current 5000 mA

Input Min Voltage 2.95 Volt

Input Max Voltage 5.5 Volt

Output Min 0.8 Volt

Output Max 5 Volt

Frequency Min 250 kHz

Frequency Max 750 kHz

Efficiency (peak) 97 %

On/Off Pin Yes

Error Flag Yes

SoftStart Yes

Sync Pin No

Inverting Undefined

Flyback Undefined

RegType Switching Regulator

Temperature Min -40 deg C

Temperature Max 125 deg C

Adjustable Output Yes

Adj Switch Frequency Yes

PWM Mode Current Mode Control

Topology Synchronous Buck

Special Features Undefined

Step-Down Yes

Multiple Output Capability No

Output Power Undefined Watt

Output Voltage Undefined Volt

Output Range 0.8V to 5.0V

Switching Frequency Undefined kHz

Feedback Voltage 0.8 Volt

Regulator Family LM20k

PowerWise Yes

Synchronous Rectification Yes

Typical Performance

click for larger image

WEBENCH Live Simulation!

LM20145
2.95 <=	V in Lower V	<=	V in Upper V	<= 5.50
V out	0.80 <=		V	<= 4.00
I out			A	<= 5.00
Ambient Temperature			°C	<= 100
What are WEBENCH® tools?

Also Recommended

LM20123▲	3A, 1.5 MHz Switching Frequency
LM20124▲	4A, 1 MHz Switching Frequency
LM20125▲	5A, 500 KHz Switching Frequency
LM20133▲	3A, Input Synchronization (500 KHz - 1.5 MHz)
LM20134▲	4A, Input Synchronization (500 KHz - 1.5 MHz)
LM20143▲	LM20143 - 3A, Adjustable Frequency (500 KHz - 1.5 MHz)
LM20144▲	4A, Adjustable Frequency (500 KHz - 1.5 MHz)
LM20154▲	4A, SYNCOUT
LM20242▲	36V, 2A Adjustable Frequency (250 KHz - 750 KHz)

Additional Resources

Design Tools

Application Notes

Block Diagram

click for larger image

Block Diagram

Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM20145 5A, PowerWise ® Adjustable Frequency Synchronous Buck Regulator	696 Kbytes	16-Jan-08	Download
LM20145 5A, PowerWise ® Adjustable Frequency Synchronous Buck Regulator (Japanese)	890 Kbytes

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Package Availability, Models, Samples & Pricing

Part Number

Package

Factory Lead Time

Models

Samples &
Electronic
Orders

Budgetary Pricing

Std
Pack
Size

Package
Marking
Format

Type

Pins

Spec.

MSL
Rating

Peak
Reflow

RoHS
Report

CAD
Symbols

Weeks

Qty

$US each

LM20145EVAL

5A, PowerWise ® Adjustable Frequency Synchronous Buck Regulator

Full production

N/A

$40.00

8 weeks

N/A

LM20145MH

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$3.00

rail
of
92

NSUZXYTT
20145
MH

6 weeks

N/A

LM20145MHE

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$3.00

reel
of
250

NSUZXYTT
20145
MH

6 weeks

N/A

LM20145MHX

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$3.00

reel
of
2500

NSUZXYTT
20145
MH

6 weeks

N/A

General Description

The LM20145 is a full featured adjustable frequency synchronous buck regulator capable of delivering up to 5A of continuous output current. The current mode control loop can be compensated to be stable with virtually any type of output capacitor. For most cases, compensating the device only requires two external components, providing maximum flexibility and ease of use. The device is optimized to work over the input voltage range of 2.95V to 5.5V making it suited for a wide variety of low voltage systems.

The device features internal over voltage protection (OVP) and over current protection (OCP) circuits for increased system reliability. A precision enable pin and integrated UVLO allows the turn-on of the device to be tightly controlled and sequenced. Start-up inrush currents are limited by both an internally fixed and externally adjustable Soft-Start circuit. Fault detection and supply sequencing is possible with the integrated power good circuit.

The LM20145 is designed to work well in multi-rail power supply architectures. The output voltage of the device can be configured to track a higher voltage rail using the SS/TRK pin. If the output of the LM20145 is pre-biased at startup it will not sink current to pull the output low until the internal soft-start ramp exceeds the voltage at the feedback pin.

The frequency of this device can be adjusted from 250 kHz to 750 kHz by connecting an external resistor from the RT pin to ground.

The LM20145 is offered in a 16-pin eTSSOP package with an exposed pad that can be soldered to the PCB, eliminating the need for bulky heatsinks.

Reliability Metrics

Part Number	Process	EFR Sample Size	LTA Device Hours	FITS	MTTF (Hours)
LM20145MH	CMOS7	18406	1089000	4	309006723
LM20145MHE	CMOS7	18406	1089000	4	309006723
LM20145MHX	CMOS7	18406	1089000	4	309006723

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.

Design Tools

Title	Size in Kbytes	Date
Current Mode Modeling - Reference Guide	1372 Kbytes	1-Aug-2007	View Online	Download
Understanding and Applying Current-Mode Control Theory	427 Kbytes	8-Jan-2008	View Online	Download
Download LM20145 Design Spreadsheet			View
Article - Reducing Buck Converter Input Capacitance through Multi-Phasing and Clock Synchronization			View

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Reference Designs

•	RD-155 - LM20145 Demonstration Board

Application Notes

Title	Size in Kbytes	Date
AN-1693: Application Note 1693 LM20145 Evaluation Board	417 Kbytes	30-Oct-07	Download
AN-1693 (Japanese): Application Note 1693 LM20145 Evaluation Board	571 Kbytes
AN-1745: Application Note 1745 Powering FPGAs Using LM201xx PowerWise® Synchronous Buck Regulators	117 Kbytes	29-Oct-07	Download
AN-1745 (Japanese): Application Note 1745 Powering FPGAs Using LM201xx PowerWise® Synchronous Buck Regulators	138 Kbytes
AN-1745 (Chinese): Application Note 1745 Powering FPGAs Using LM201xx PowerWise® Synchronous Buck Regulators	231 Kbytes
AN-1752: Application Note 1752 5A LM20k Reference Designs	174 Kbytes	13-Nov-07	Download

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More Application Notes

Title	Size in Kbytes	Date
AN-1747: Application Note 1747 3A LM20k Reference Designs	227 Kbytes	9-Nov-07	Download
AN-1751: Application Note 1751 4A LM20k Reference Designs	206 Kbytes	9-Nov-07	Download
AN-1902: Application Note 1902 LM20146 Evaluation Board	1685 Kbytes	19-Jan-09	Download
AN-1692: Application Note 1692 LM20144 Evaluation Board	414 Kbytes	30-Oct-07	Download
AN-1692 (Japanese): Application Note 1692 LM20144 Evaluation Board	588 Kbytes
AN-1691: Application Note 1691 LM20143 Evaluation Board	526 Kbytes	30-Oct-07	Download
AN-1691 (Japanese): Application Note 1691 LM20143 Evaluation Board	764 Kbytes

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[Information as of 7-Nov-2009]