Features • Step-up, step-down or inverting switching regulators • Output adjustable from 1.25V to 40V • Peak currents to 1.5A without external transistors • Operation from 2.5V to 40V input • Low standby current drain • 80 dB line and load regulation • High gain, high current, independent op amp • Pulse width modulation with no double pulsing Description The LM78S40 is a monolithic regulator subsystem consisting of all the active building blocks necessary for switching regulator systems. The device consists of a temperature compensated voltage reference, a duty-cycle controllable oscillator with an active current limit circuit, an error amplifier, high current, high voltage output switch, a power diode and an uncommitted operational amplifier. The device can drive external NPN or PNP transistors when currents in excess of 1.5A or voltages in excess of 40V are required. The device can be used for step-down, step-up or inverting switching regulators as well as for series pass regulators. It features wide supply voltage range, low standby power dissipation, high efficiency and low drift. It is useful for any stand-alone, low part count switching system and works extremely well in battery operated systems.

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	Connection Diagram *click for larger image

Datasheets

Title		Size	Date	Other Language
	LM78S40 Universal Switching Regulator Subsystem	289 Kbytes	1-May-98
	LM78S40 Mil-Aero Datasheet MNLM78S40-X	15 Kbytes

Featured Application Notes

Title		Size	Date	Other Language
	AN-711: Application Note 711 LM78S40 Switching Voltage Regulator Applications	490 Kbytes	3-Oct-02

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Standard Pack Size
LM78S40CN/NOPB LM78S40CN RoHS Status	MDIP	Full production Lead Time: 12 weeks	Distributor Region Qty ARROW Worldwide 375 AVNET-EM Worldwide 1148 BRITESTONE South Korea 1000 DIGIKEY Worldwide 591 FARNELL Europe and Asia 1763 TAYLOR Americas 2000	$0.68 each at 1K+ pcs	rail of 25
LM78S40N/NOPB LM78S40N RoHS Status	MDIP	Full production Lead Time: 12 weeks	Distributor Region Qty DIGIKEY Worldwide 0 RS COMPONENTS Worldwide 70 TAYLOR Americas 220	$0.85 each at 1K+ pcs	rail of 25

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM78S40C MDA	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM78S40J/883	NONE	NATIONAL SEMICONDUCTOR	01 Dec 2009

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.

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.

CAD Symbols and Models N/A

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM78S40CN	SLM	0	44046	0	0	3532500	1	1002356520
LM78S40J/883	SLM	0	44046	0	0	3532500	1	1002356520
LM78S40N	SLM	0	44046	0	0	3532500	1	1002356520

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.

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM78S40C MDA	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM78S40J/883	NONE	NATIONAL SEMICONDUCTOR	01 Dec 2009