LM20242 - 36V, 2A PowerWise Adjustable Frequency Synchronous Buck Regulator

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

Features

•	2A Output Current, 3.7A peak current
•	130 mΩ/110 mΩ integrated power MOSFETs
•	1.5% output voltage accuracy
•	Current Mode Control, selectable compensation
•	Resistor programmed, 1MHz capable oscillator
•	Synchronous rectifier with diode emulation
•	Adjustable output voltage down to 0.8V
•	Compatible with pre-biased loads
•	Programmable soft-start with external capacitor
•	Precision enable pin with hysteresis
•	OVP, UVLO inputs and PGOOD output
•	Internally protected with peak current limit, thermal shutdown and restart
•	Accurate current limit with frequency foldback
•	Non-linear current mode slope compensation
•	eTSSOP-20 exposed pad package

General Description

The LM20242 is a full featured 1MHz capable synchronous buck regulator capable of delivering up to 2A of load current. More...

Applications

•	Simple to design, high efficiency point of load regulation from a 4.5V to 36V bus
•	High Performance DSPs, FPGAs, ASICs and Microprocessors
•	Communications Infrastructure, Automotive

Typical Application

*click for larger image

Parameters Values

Output Current 2000 mA

Input Min Voltage 4.5 Volt

Input Max Voltage 36 Volt

Output Min 0.8 Volt

Output Max 32 Volt

Frequency Min 100 kHz

Frequency Max 1000 kHz

Efficiency (peak) 96 %

On/Off Pin Yes

Error Flag Yes

SoftStart Yes

Sync Pin No

Inverting No

Flyback No

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 Undefined

Switching Frequency 1000 kHz

Feedback Voltage 0.8 Volt

Regulator Family LM20k

PowerWise Yes

Synchronous Rectification Yes

Typical Performance

click for larger image

WEBENCH Live Simulation!

LM20242
4.50 <=	V in Lower V	<=	V in Upper V	<= 36.00
V out	0.80 <=		V	<= 33.00
I out			A	<= 2.00
Ambient Temperature			°C	<= 100
What are WEBENCH® tools?

Also Recommended

LM20323▲	36V,3A PowerWise 500 KHz Synchronous Buck Regulator
LM20343▲	36V,3A PowerWise Adjustable Frequency Synchronous Buck Regulator
LM3100▲	Simple Switcher Synchronous 1MHz 1.5A Step-Down Voltage Regulator
LM3102▲	Simple Switcher Synchronous 1MHz 2.5A Step-Down Voltage Regulator
LM3103▲	Simple Switcher Synchronous 1MHz 750mA Step-Down Voltage Regulator

Additional Resources

Design Tools

Block Diagram

click for larger image

Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM20242 36V, 2A PowerWise ® Adjustable Frequency Synchronous Buck Regulator	469 Kbytes	29-May-08	Download
LM20242 36V, 2A PowerWise ® Adjustable Frequency Synchronous Buck Regulator (Japanese)	761 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

LM20242EVAL

36V, 2A PowerWise® Adjustable Frequency Synchronous Buck Regulator

Full production

N/A

$40.00

8 weeks

N/A

LM20242MH

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$2.60

rail
of
73

NSUZXYTT
20242
MH

12 weeks

N/A

LM20242MHE

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$2.60

reel
of
250

NSUZXYTT
20242
MH

8 weeks

N/A

LM20242MHX

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$2.60

reel
of
2500

NSUZXYTT
20242
MH

12 weeks

N/A

General Description

The LM20242 is a full featured 1MHz capable synchronous buck regulator capable of delivering up to 2A of load current. The current mode control loop is externally compensated with only two external components, offering both high performance and ease of use. The device is optimized to work over the input voltage range of 4.5V to 36V making it well suited for high 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. Startup inrush currents are limited by both an internally fixed and externally adjustable soft-start circuit. Fault detection and supply sequencing are possible with the integrated PGOOD circuit.

The LM20242 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 LM20242 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 LM20242 is offered in an exposed pad 20 pin TSSOP package 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)
LM20242MH	ABCD150	34175	4234000	1	1201409060
LM20242MHE	ABCD150	34175	4234000	1	1201409060
LM20242MHX	ABCD150	34175	4234000	1	1201409060

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 LM20242 Calculator spreadsheet			View
Article - Reducing Buck Converter Input Capacitance through Multi-Phasing and Clock Synchronization			View
Article - Hitchhiker's Ride to the World of Current Mode Control			View

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Reference Designs

•	RD-156 - LM20242 Demonstration Board

Application Notes

Title	Size in Kbytes	Date
AN-1694: Application Note 1694 LM20242 Evaluation Board	522 Kbytes	30-Oct-07	Download
AN-1694 (Japanese): Application Note 1694 LM20242 Evaluation Board	471 Kbytes

If you have trouble printing or viewing PDF file(s), see Printing Problems.

[Information as of 7-Nov-2009]