Features • 200 kHz fixed-frequency switching • Switching synchronization with an external signal up to 400 kHz • Optional pulse-skipping mode • Adjustable secondary feedback • Input undervoltage lockout • Output undervoltage shutdown protection • Output overvoltage shutdown protection • Programmable soft-start (each controller) • 5V, 50 mA linear regulator output • Precision 2.5V reference output • 28-pin TSSOP Description The LM2640 is a dual step-down power supply controller intended for application in notebook personal computers and other battery-powered equipment. Fixed-frequency synchronous drive of logic-level N-channel power MOSFETs is combined with an optional pulse-skipping mode to achieve ultra efficient power conversion over a 1000:1 load current range. The pulse-skipping mode can be disabled in favor of fixed-frequency operation regardless of the load current level. High DC gain and current-mode feedback control assure excellent line and load regulation and a wide loop bandwidth for fast response to dynamic loads. An internal oscillator fixes the switching frequency at 200 kHz. Optionally, switching can be synchronized to an external clock running as fast as 400 kHz. An optional soft-start feature limits current surges from the input power supply at start up and provides a simple means of start-up sequencing. Logic-level inputs allow the controllers to be turned ON and OFF separately. Key Specification • 96% efficient • 5.5 to 30V input range • Dual outputs adjustable from 2.2 to 6V • 0.5% typical load regulation error • 0.002%/V typical line regulation error Applications • Notebook and subnotebook computers • Wireless data terminals • Battery-powered instruments

Also Recommended LM2641▲ 300kHz Switching Frequency 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
	LM2640 Dual Adjustable Step-Down Switching Power Supply Controller	504 Kbytes	15-May-01	日本語

Featured Application Notes

Title		Size	Date	Other Language
	AN-1146: Application Note 1146 Designing a Multi-phase Asynchronous Buck Regulator Using the LM2639	127 Kbytes	10-May-04

More Application Notes

Title		Size	Date	Other Language
	AN-1146: Application Note 1146 Designing a Multi-phase Asynchronous Buck Regulator Using the LM2639	127 Kbytes	10-May-04
	AN-1208: Application Note 1208 LM2633 Evaluation Board	700 Kbytes	10-May-04

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2640MTC-ADJ	LMDMOS	0	17710	0	0	2470000	2	700869244
LM2640MTCX-ADJ	LMDMOS	0	17710	0	0	2470000	2	700869244

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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