Features Low voltage supply (3V–5.5V) 22 mA output drive current No RFI radiation Adaptable to all injector current levels Highly accurate operation TTL/CMOS compatible input logic levels Short circuit protection High impedance input Externally set holding current, IH Internally set peak current (4 × IH) Externally set time-out Can be modified for full switching operation Available in plastic 8-pin minDIP Description The LM1949 linear integrated circuit serves as an excellent control of fuel injector drive circuitry in modern automotive systems. The IC is designed to control an external power NPN Darlington transistor that drives the high current injector solenoid. The current required to open a solenoid is several times greater than the current necessary to merely hold it open; therefore, the LM1949, by directly sensing the actual solenoid current, initially saturates the driver until the “peak” injector current is four times that of the idle or “holding” current ( – ). This guarantees opening of the injector. The current is then automatically reduced to the sufficient holding level for the duration of the input pulse. In this way, the total power consumed by the system is dramatically reduced. Also, a higher degree of correlation of fuel to the input voltage pulse (or duty cycle) is achieved, since opening and closing delays of the solenoid will be reduced. Normally powered from a 5V ± 10% supply, the IC is typically operable over the entire temperature range (−55°C to +125°C ambient) with supplies as low as 3 volts. This is particularly useful under “cold crank” conditions when the battery voltage may drop low enough to deregulate the 5-volt power supply. The LM1949 is available in the plastic miniDIP, (contact factory for other package options). Applications Fuel injection Throttle body injection Solenoid controls Air and fluid valves DC motor drives

Typical Application click for larger image	Connection Diagram click for larger image LM1949N (N08E) Connection Diagram
Typical Performance click for larger image

Datasheets

Title		Size	Date	Other Language
	LM1949 Injector Drive Controller	374 Kbytes	14-Dec-08

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM1949N/NOPB LM1949N RoHS Status	MDIP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 1 DIGI-KEY Worldwide 40 FARNELL Europe and Asia 256 MOUSER Worldwide 87 NEWARK Americas 258 TAYLOR Americas 899	$2.05 each at 1K+ pcs	rail of 40

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM1949M	NONE	NONE	10 Mar 1998

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

Moisture Sensitivity Level Data for LM1949.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM1949 is located at RoHS Status.

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM1949N/NOPB LM1949N	508.252 510.002	MDIP	8	1 1	NA NA	Detail	N/A	N/A	NSUZXYTTE# LM 1949N

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

Moisture Sensitivity Level Data for LM1949.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM1949 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)
LM1949N	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/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM1949.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM1949 is located at RoHS Status.

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM1949M	NONE	NONE	10 Mar 1998