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 (Figure 3Figure 7) 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