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 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. 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

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 What are WEBENCH® tools? MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application *click for larger image	Block Diagram click for larger image
Typical Performance click for larger image

Datasheet

Title		Size	Date	Other Language
	LM20343 36V, 3A Adjustable Frequency Synchronous Buck Regulator	550 Kbytes	12-Aug-08

Featured Application Notes

Title		Size	Date	Other Language
	AN-1792: Application Note 1792 LM20343 Evaluation Board	922 Kbytes	1-Oct-08

More Application Notes

Title		Size	Date	Other Language
	AN-1745: Application Note 1745 Powering FPGAs Using LM201xx PowerWise® Synchronous Buck Regulators	117 Kbytes	29-Oct-07	日本語 中文

Design Tools

Title	Size	Date
Download LM20343 Calculator spreadsheet	1044 Kbytes	2-Jun-2008

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM20343MH	ABCD150	0	34175	0	0	4234000	1	1201409060
LM20343MHE	ABCD150	0	34175	0	0	4234000	1	1201409060
LM20343MHX	ABCD150	0	34175	0	0	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.

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