LM5642   
High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization from the PowerWise® Family		 Click link to Download

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

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. The two switching regulator outputs can also be paralleled to operate as a dual-phase, single output regulator.

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.

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

Also Recommended
LM2647Dual 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



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                                              LM5642
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Also Recommended
LM2647Dual 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
Paramaters / ValuesLM5642 LM5642X LM2633 LM2642 LM2648
Output Current20000 mA 20000 mA 20000 mA
Input Min Voltage4.5 Volt 4.5 Volt 4.5 Volt
Input Max Voltage36 Volt 36 Volt 30 Volt
Feedback Voltage1.2364 Volt 1.2364 Volt 1.238 Volt
Feedback Tolerance1.5 % 1.5 % 2 %
Frequency Min150 kHz 200 kHz 300 kHz
Frequency Max250 kHz 500 kHz 300 kHz
Efficiency (peak)90 % 90 % Undefined %
Output Range1.3V to 96% of Vin 1.3V to 96% of Vin 1.238V-27V (each output)
Adj Switch FrequencyYes Yes No
Adjustable OutputYes Yes Yes
Synchronous RectificationYes Yes Yes
On/Off PinYes Yes Yes
Error FlagNo No Yes
SoftStartYes Yes Yes
Sync PinYes Yes No
InvertingNo No No
FlybackNo No No
Lossless Current SenseYes Yes Yes
RegTypeSwitching Controller Switching Controller Switching Controller
Temperature Min-40 deg C -40 deg C -40 deg C
Temperature Max125 deg C 125 deg C 125 deg C
Channels2 Channels 2 Channels 2 Channels
Special Features180deg out-of-phase channels; individual soft-start allows sequencing 180deg out-of-phase channels; individual soft-start allows sequencing 180deg out-of-phase channels; Individual softstart allows sequencing
TopologyBuck Buck Buck
PWM ModeCurrent Current Current
Step-DownYes Yes Yes
Step-UpNo No No
Output PowerUndefined Watt Undefined Watt Undefined Watt
Output Min1.3 Volt 1.3 Volt 1.238 Volt
PowerWiseYes Yes

Datasheets
TitleSizeDateOther
Language
LM5642/LM5642X High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization793
Kbytes		20-Jun-07 


Featured Application Notes
TitleSizeDateOther
Language
AN-1292: Application Note 1292 LM5642 Evaluation Board2111
Kbytes		2-Sep-03 

Part Number(s)
(NSID)		Top ViewAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM5642MH/NOPB

RoHS Status



TSSOP EXP PAD		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
ARROWWorldwide2182
DIGIKEYWorldwide125
FUTUREWorldwide92
NEWARKAmericas183
$1.90 each at 1K+ pcsrail
of
48
LM5642MHX/NOPB

RoHS Status



TSSOP EXP PAD		Full production
Lead Time: 16 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$1.90 each at 1K+ pcsreel
of
2500
LM5642MTC/NOPB
LM5642MTC

RoHS Status



TSSOP		Full production
Lead Time: 12 weeks

Samples
DistributorRegionQty
ARROWWorldwide238
AVNET-EMWorldwide105
DIGIKEYWorldwide0
FUTUREWorldwide1100
KEIKONGAsia Pacific40
NEWARKAmericas61
RS COMPONENTSWorldwide10
$1.90 each at 1K+ pcsrail
of
48
LM5642MTCX/NOPB
LM5642MTCX

RoHS Status



TSSOP		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
KEIKONGAsia Pacific5000
TECHMOSAAsia Pacific10000
$1.90 each at 1K+ pcsreel
of
2500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Part Number(s)
(NSID)		DescriptionAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM5642EVAL-KIT
High Voltage, Dual Synchronous Buck Converter with Oscillator SynchronizationFull production


 
DistributorRegionQty
DIGIKEYWorldwide0
NATIONALWorldwide5
$180.00 each1

High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization

Features:

  • Two synchronous buck regulators
  • 180° out of phase operation
  • Synchronizable switching frequency from 150 kHz to 250 kHz
  • 4.5 V to 36 V input range
  • 50µA shutdown current
  • Adjustable output from 1.3 V to 90% of Vin
  • 0.04% (typical) line and load regulation error
  • 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.
  • 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 package

Applications:

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

Contents:

  • A fully assembled LM5642 evaluation board
  • LM5642 evaluation board appnote
  • LM5642 datasheet

Part Number(s)
(NSID)		Top ViewTypePinsMSL RatingPeak ReflowRoHS
Status		CAD SymbolsModelsPackage
Marking
Format
LM5642MH/NOPB
TSSOP EXP PAD281260DetailDownloadN/A
NSUZXYTTE#
LM5642
MH
LM5642MHX/NOPB
TSSOP EXP PAD281260DetailDownloadN/A
NSUZXYTTE#
LM5642
MH
LM5642MTC/NOPB
LM5642MTC
TSSOP283
3		260
235		DetailDownloadN/A
NSUZXYTTE#
LM5642
MTC
LM5642MTCX/NOPB
LM5642MTCX
TSSOP283
3		260
235		DetailDownloadN/A
NSUZXYTTE#
LM5642
MTC

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Reliability Metrics
Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM5642MHABCD15003417500423400011201409060
LM5642MHXABCD15003417500423400011201409060
LM5642MTCABCD15003417500423400011201409060
LM5642MTCXABCD15003417500423400011201409060

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.


All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

[Information as of 9-Feb-2010]