LM5642 - High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization

	LM5642 - High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization from the PowerWise® Family

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

Features

•	Two synchronous buck regulators
•	180° out of phase operation
•	200kHz fixed nominal frequency: LM5642
•	375kHz fixed nominal frequency: LM5642X
•	Synchronizable switching frequency from 150kHz to 250kHz for the LM5642 and 200kHz to 500kHz for the LM5642X
•	4.5V to 36V input range
•	50µA Shutdown current
•	Adjustable output from 1.3V to 90% of Vin
•	0.04% (typical) line and load regulation accuracy
•	Current mode control with or without a sense resistor
•	Independent enable/soft-start pins allow simple sequential startup configuration.
•	Configurable for single output parallel operation. (See )
•	Adjustable cycle-by-cycle current limit
•	Input under-voltage lockout
•	Output over-voltage latch protection
•	Output under-voltage protection with delay
•	Thermal shutdown
•	Self discharge of output capacitors when the regulator is OFF
•	TSSOP and eTSSOP (Exposed PAD) packages

General Description

The LM5642 series consists of two current mode synchronous buck regulator controllers operating 180° out of phase with each other at a normal switching frequency of 200kHz for the LM5642 and at 375kHz for the LM5642X.

Out of phase operation reduces the input RMS ripple current, thereby significantly reducing the required input capacitance. The switching frequency can be synchronized to an external clock between 150kHz and 250kHz for the LM5642 and between 200 kHz and 500 kHz for the LM5642X. More...

Applications

•	Embedded Computer Systems
•	Navigation Systems
•	Telecom Systems
•	Set-Top Boxes
•	WebPAD
•	Point Of Load Power Architectures

Typical Application

*click for larger image

Parametric Table expand

Parametric Table collapse

Output Current 20000 mA

Input Min Voltage 4.5 Volt

Input Max Voltage 36 Volt

Feedback Voltage 1.2364 Volt

Feedback Tolerance 1.5 %

Frequency Min 150 kHz

Frequency Max 250 kHz

Efficiency (peak) 90 %

Output Current 20000 mA

Input Min Voltage 4.5 Volt

Input Max Voltage 36 Volt

Feedback Voltage 1.2364 Volt

Feedback Tolerance 1.5 %

Frequency Min 150 kHz

Frequency Max 250 kHz

Efficiency (peak) 90 %

Output Range 1.3V to 96% of Vin

Adj Switch Frequency Yes

Adjustable Output Yes

Synchronous Rectification Yes

On/Off Pin Yes

Error Flag No

SoftStart Yes

Sync Pin Yes

Inverting No

Flyback No

Lossless Current Sense Yes

RegType Switching Controller

Temperature Min -40 deg C

Temperature Max 125 deg C

Channels 2 Channels

Special Features 180deg out-of-phase channels; individual soft-start allows sequencing

Topology Buck

PWM Mode Current

Step-Down Yes

Step-Up No

Output Power Undefined Watt

Output Min 1.3 Volt

PowerWise Yes

View Using Catalog

Typical Performance

*click for larger image

Ch.2 Efficiency at 3.3Vout

Also Recommended

LM2647	Dual Synchronous Buck Controller With Output Voltages As Low As 0.6V
LM5642X	200-500 KHz Osc Switch Frequencies
LM2633	Dual Sync Buck + LDO Controller. Perfect For FPGAs And Similar Devices
LM2642	Pin Compatible Except That SYNC Is Replaced By PGOOD, And Has 300 KHz Fixed Frequency
LM2648	Triple / Quad Channel Syncronous Buck Controller

Additional Resources

Design Tools (see below)

Block Diagram

click for larger image

Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM5642/LM5642X High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization	793 Kbytes	20-Jun-07	View Online Download

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

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

LM5642EVAL-KIT

High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization

Full production

N/A

$180.00

8 weeks

N/A

LM5642MTC

TSSOP

STD

NOPB

235

260

RoHS

Download

Full production

N/A

1K+

$1.80

rail
of
48

NSUZXYTT
LM5642
MTC

8 weeks

5000

LM5642MTCX

TSSOP

STD

NOPB

235

260

RoHS

Download

Full production

N/A

1K+

$1.80

reel
of
2500

NSUZXYTT
LM5642
MTC

6 weeks

3000

LM5642MH

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$1.80

rail
of
48

NSUZXYTT
LM5642
MH

8 weeks

N/A

LM5642MHX

TSSOP EXP PAD

NOPB

260

RoHS

Download

Full production

N/A

1K+

$1.80

reel
of
2500

NSUZXYTT
LM5642
MH

6 weeks

N/A

General Description

The output of each channel can be independently adjusted from 1.3V to 90% of Vin. An internal 5V rail is also available externally for driving bootstrap circuitry.

Current-mode feedback control assures excellent line and load regulation and wide loop bandwidth for excellent response to fast load transients. Current is sensed across either the Vds of the top FET or across an external current-sense resistor connected in series with the drain of the top FET.

The LM5642 features analog soft-start circuitry that is independent of the output load and output capacitance making the soft-start behavior more predictable and controllable than traditional soft-start circuits.

Over-voltage protection is available for both outputs. A UV-Delay pin is also available to allow delayed shut off time for the IC during an output under-voltage event.

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM *	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM5642MH	ABCD150	0	28280	0	0	2974000	2	843880620
LM5642MHX	ABCD150	0	28280	0	0	2974000	2	843880620
LM5642MTC	ABCD150	0	28280	0	0	2974000	2	843880620
LM5642MTCX	ABCD150	0	28280	0	0	2974000	2	843880620

Note: The Early Failure Rates were calculated as point estimates. 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
Power Reference Design Library	0 Kbytes	28-Mar-2006	View
Reducing Buck Converter Input Capacitance through Multi-Phasing and Clock Synchronization			View

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Application Notes

Title	Size in Kbytes	Date
AN-1292: Application Note 1292 LM5642 Evaluation Board	2111 Kbytes	2-Sep-03	Download

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

[Information as of 21-Nov-2008]