LM1949

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SNLS349C – FEB 1995 – REVISED MARCH 2013

LM1949 Injector Drive Controller

Check for Samples: LM1949

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FEATURES

DESCRIPTION

The LM1949 linear integrated circuit serves as an

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•

Low Voltage Supply (3V–5.5V)

excellent control of fuel injector drive circuitry in

•

22 mA Output Drive Current

modern automotive systems. The IC is designed to

•

No RFI Radiation

control an external power NPN Darlington transistor

that drives the high current injector solenoid. The

•

Adaptable to All Injector Current Levels

current required to open a solenoid is several times

•

Highly Accurate Operation

greater than the current necessary to merely hold it

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TTL/CMOS Compatible Input Logic Levels

open; therefore, the LM1949, by directly sensing the

actual solenoid current, initially saturates the driver

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Short Circuit Protection

until the “peak” injector current is four times that of

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High Impedance Input

the idle or “holding” current (Figure 19–Figure 22).

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Externally Set Holding Current, IH

This guarantees opening of the injector. The current

is then automatically reduced to the sufficient holding

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Internally Set Peak Current (4 × IH)

level for the duration of the input pulse. In this way,

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Externally Set Time-Out

the

total

power

consumed

by

the

system

is

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Can be Modified for Full Switching Operation

dramatically reduced. Also, a higher degree of

•

Available in Plastic 8-Pin PDIP

correlation of fuel to the input voltage pulse (or duty

cycle) is achieved, since opening and closing delays

of the solenoid will be reduced.

APPLICATIONS

Normally powered from a 5V ± 10% supply, the IC is

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Fuel Injection

typically operable over the entire temperature range

•

Throttle Body Injection

(

−55°C to +125°C ambient) with supplies as low as 3

•

Solenoid Controls

volts. This is particularly useful under “cold crank”

•

Air and Fluid Valves

conditions when the battery voltage may drop low

enough to deregulate the 5-volt power supply.

•

DC Motor Drives

The LM1949 is available in the plastic PDIP, (contact

factory for other package options).

Typical Application

Figure 1. Typical Application and Test Circuit

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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

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PRODUCTION DATA information is current as of publication date.

Copyright © 1995–2013, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.