LM20343 - 36V, 3A Adjustable Frequency Synchronous Buck Regulator from the PowerWise® Family
Datasheet Packaging Samples & Pricing Eval. Boards Reliability Design Tools Knowledge Base

Features
•4.5V to 36V input voltage range
•3A output current, 5.2A peak current
•130 mΩ/110 mΩ integrated power MOSFETs
•94% peak efficiency with synchronous rectification
•1.5% feedback voltage accuracy
•Current mode control, selectable compensation
•Resistor programmed, 1MHz capable oscillator
•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 minimizes inductor size
•Non-linear current mode slope compensation
•eTSSOP-20 exposed pad package

General Description

The LM20343 is a full featured synchronous buck regulator capable of delivering up to 3A 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


ParametersValues
Output Current 3000 mA
Input Min Voltage 4.5 Volt
Input Max Voltage 36 Volt
Output Min 0.8 Volt
Output Max 32 Volt
Frequency Min 250 kHz
Frequency Max 1000 kHz
Efficiency (peak) 94 %
On/Off Pin Yes
Error Flag Yes
SoftStart Yes
Sync Pin Yes
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 Undefined kHz
Feedback Voltage 0.8 Volt
Regulator Family LM20k
Automotive Yes
PowerWise Yes
Synchronous Rectification Yes


Typical Performance

click for larger image


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LM20343
 
4.50 <=		 V in Lower
 V		  
<=		 V in Upper
 V		  
<= 36.00
V out 0.80 <=  V <= 32.00
I out    A <= 3.00
Ambient Temperature  °C <= 100


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Additional Resources
Design Tools


Block Diagram

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Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM20343 36V, 3A Adjustable Frequency Synchronous Buck Regulator 550
Kbytes		 12-Aug-08 Download

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


Package Availability, Models, Samples & Pricing
Part NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders		Budgetary PricingStd
Pack
Size		Package
Marking
Format
TypePinsSpec.MSL
Rating		Peak
Reflow		RoHS
Report		CAD
Symbols		WeeksQtyQty$US each
LM20343MHTSSOP EXP PAD20NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$3.02rail
of
73		NSUZXYTT
20343MH
6 weeksN/A
LM20343MHETSSOP EXP PAD20NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$3.02reel
of
250		NSUZXYTT
20343MH
8 weeksN/A
LM20343MHXTSSOP EXP PAD20NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$3.02reel
of
2500		NSUZXYTT
20343MH
6 weeksN/A
LM20343EVALEvaluation Board for the LM20343Full productionN/A
 
Buy Now 		1+$55.001-
8 weeks10

General Description

The LM20343 is a full featured synchronous buck regulator capable of delivering up to 3A of load current. The current mode control loop is externally compensated with only two 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 power good (PGOOD) circuit.

The frequency of this device can be adjusted from 250 kHz to 1.0 MHz by connecting an external resistor from the RT pin to ground.

The LM20343 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 LM20343 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 LM20343 is offered in an exposed pad 20-pin eTSSOP package that can be soldered to the PCB, eliminating the need for bulky heatsinks.

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM20343MHABCD15003417500423400011201409060
LM20343MHEABCD15003417500423400011201409060
LM20343MHXABCD15003417500423400011201409060

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

TitleSize in Kbytes Date Click link below to Download    
Download LM20343 Calculator spreadsheet 1044 Kbytes 2-Jun-2008 View    

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

Application Notes

TitleSize in Kbytes Date Click link below to Download
AN-1792: Application Note 1792 LM20343 Evaluation Board 922
Kbytes		 1-Oct-08 Download

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

[Information as of 8-Nov-2009]