Fuel pump driver circuit

Claim 2

In a driver circuit for a fuel pump for an internal combustion engine, which engine produces a signal indicating engine operation, the combination including: first means for receiving the signal from the engine, capacitor means, current supply means, circuit means including a load terminal and second means coupling said current supply means to said load terminal for controlling the application of current thereto, and control means coupled to said first means and to said capacitor means and including means for discharging said capacitor means in response to a signal indicating engine operation, said control means including means for charging said capacitor means and being coupled to said second means and operating in response to the voltage across said capacitor means produced in the absence of a singal indicating engine operation to control said second means to uncouple said load terminal from said supply means.

Claim 3

The combination according to claim 1 including switch means coupling said current supply means to said circuit means and having on and off conditions.

Claim 4

The combination according to claim 1 wherein said circuit means and said control means are provided as an integrated circuit chip.

Claim 5

The combination according to claim 1 wherein said second means includes a switch transistor having control, common and output electrodes, said common electrode being coupled to said current supply means, said output electrode being coupled to said load terminal, and means coupled between said control means and said control electrode to control said transistor for causing the same to selectively supply current to said load terminal.

Claim 6

The combination according to claim 1 wherein said capacitor means forms energy storage means for delaying the action of said control means to uncouple said current supply means from said load terminal.

Claim 7

The combination according to claim 1 wherein said control means includes a control transistor having control, output and common electrodes, said common electrode being coupled to reference ground potential, and said output electrode being coupled to said second means, and a differential switch coupled between said first means for receiving signals from the engine and said control electrode of said control transistor, said differential switch having on and off conditions, and being in said off condition to render said control transistor conducting in the absence of a signal from the engine by said signal receiving means.

Claim 8

A driver circuit for an electrically operated device associated with apparatus which produces a signal indicating that the apparatus is operating, including in combination: current supply means, load terminal means; an output transistor having control, common and output electrodes said common electrode being coupled to said current supply means, said output electrode being coupled to said load terminal means; differential switch means including first and second transistors of the same conductivity type, each having control, common and first and second output electrodes, said common electrode of each of said first and second transistors being coupled to said current supply means, means providing a reference potential connected to said control electrode of said first transistor, said first output electrode of said first transistor being coupled to said control electrode of said second transistor; means coupling said second output electrode of said first transistor to said control electrode of said output transistor; a capacitor coupled between said input electrode of said second transistor and the ground reference potential, means connecting said first output electrode of said second transistor to said capacitor for charging the same, said second output electrode of said second transistor being connected to a reference potential; an input transistor having control and output electrodes, means applying the signal indicating operation of the apparatus to said control electrode, means connecting said output electrodes across said capacitor for discahrging the same in response to the operation signal; said capacitor charging to render said first transistor conducting in the absence of the operation signal to hold said differential switch in the off condition, and render said output transistor nonconducting to disconnect said current supply means from said load terminal means.

Claim 9

A driver circuit for an electrically operated device associated with apparatus which produces a signal indicating that the apparatus is operating, including in combination: current supply means, load terminal means; an output transistor having control, common and output electrodes said common electrode being coupled to said current supply means, said output electrode being coupled to said load terminal means; differential switch means including first and second transistors of the same conductivity type, each having control, common and first and second output electrodes, said common electrode of each of said first and second transistors being coupled to said current supply means, means providing a reference potential connected to said control electrode of said first transistor, said first output electrode of said first transistor being coupled to said control electrode of said second transistor; means coupling said second output electrode of said first transistor to said control electrode of said output transistor; a capacitor coupled between said input electrode of said second transistor and the ground reference potential, means connecting said first output electrode of said second transistor to said capacitor for charging the same, said second output electrode of said second transistor being connected to a reference potential; an input transistor having control and output electrodes, means applying the signal indicating operation of the apparatus to said control electrode, means connecting said output electrodes across said capacitor for discahrging the same in response to the operation signal; said capacitor charging to render said first transistor conducting in the absence of the operation signal to hold said differential switch in the off condition, and render said output transistor nonconducting to disconnect said current supply means from said load terminal means.

Claim 10

A driver circuit in accordance with claim 7 including resistance means connected between said first output electrode of said first transistor and said capacitor means for charging said capacitor means in the absence of the operation signal, said capacitor providing a predetermined time to charge to thereby delay the conduction of said first transistor and the disconnection of said current supply means from said load terminal means.

Claim 11

A driver circuit in accordance with claim 7 wherein said means coupling said second output electrode of said first transistor to said control electrode of said output transistor includes a control transistor having control, common and output electrodes, said common electrode being coupled to the reference ground potential, said output electrode being coupled to said control electrode of said output transistor to control the conductivity of said output transistor to control the supply of current to said load terminals, and means connecting said second output electrode of said first transistor to said control electrode of said control transistor.

Claim 12

The driver circUit in accordance with claim 9 further including resistance means connecting said control electrode of said output transistor to said current supply means.