Squib control circuit
View Patent ↗An improved control circuit that is structured to energize another device such as a squib. A first portion of the circuit includes a first transistor and is structured to discharge at a first rate a first portion of a charge stored by a capacitor. Another portion of the circuit includes a second transistor and is structured to discharge a second portion of the charge subsequent to the discharge of the first portion of the charge and at a second rate greater than the first rate.
1. A circuit structured to energize another device, the circuit comprising:
a capacitor structured to at least temporarily store a charge;
a FIRE switch;
a portion of the circuit comprising a first solid state switch and being structured to discharge a first portion of the charge at a first rate;
another portion of the circuit comprising a second solid state switch and being structured to discharge a second portion of the charge subsequent to the discharge of the first portion of the charge and at a second rate greater than the first rate; and
the capacitor having stored therein prior to the onset of the discharge of the second portion of the charge an energizing portion of the charge sufficient to energize the other device; and
the FIRE switch being actuatable to discharge the energizing portion of the charge and to thereby energize the another device prior to the onset of the discharge of the second portion of the charge.
2. The circuit of claim 1 wherein the first solid state switch is a first transistor, and wherein the second solid state switch is a second transistor.
3. The circuit of claim 2 wherein the portion of the circuit comprises a Zener diode connected between a terminal of the capacitor and a gate of the first transistor.
4. A circuit structured to energize another device, the circuit comprising:
a capacitor structured to at least temporarily store a charge;
a portion of the circuit comprising a first solid state switch and being structured to discharge a first portion of the charge at a first rate;
another portion of the circuit comprising a second solid state switch and being structured to discharge a second portion of the charge subsequent to the discharge of the first portion of the charge and at a second rate greater than the first rate;
the capacitor having stored therein prior to the onset of the discharge of the second portion of the charge a portion of the charge sufficient to energize the other device;
wherein the portion of the circuit comprises a Zener diode connected between a terminal of the capacitor and a gate of the first transistor; and
wherein the portion of the circuit further comprises at least a first resistor that is connected with an electrode of the first transistor and that is structured to be further connected with the terminal of the capacitor, at least one of the resistance of the at least first resistor and the breakdown voltage of the Zener diode being selected at least in part to cause the capacitor to retain for at least a predetermined period of time during the discharge of the first portion of the charge the portion of the charge sufficient to energize the other device.
5. The circuit of claim 4 wherein at least a part of the another portion of the circuit is selected at least in part to cause a predetermined voltage across the terminals of the capacitor to be reached within another predetermined period of time after the onset of the discharge of the first portion of the charge.
6. The circuit of claim 1 wherein a further portion of the circuit is structured to discharge a remaining portion of the charge subsequent to the discharge of the second portion of the charge and at a third rate less than the first rate.
7. The circuit of claim 3 wherein the portion of the circuit further comprises at least a first resistor that is connected between the terminal of the capacitor and an electrode of the first transistor, and wherein the electrode of the first transistor is further connected with a gate of the second transistor.
8. The circuit of claim 7 wherein an electrode of the second transistor is connected with the terminal of the capacitor.
9. A circuit structured to energize another device, the circuit comprising:
a capacitor structured to at least temporarily store a charge;
a portion of the circuit comprising a first solid state switch and being structured to discharge a first portion of the charge at a first rate;
another portion of the circuit comprising a second solid state switch and being structured to discharge a second portion of the charge subsequent to the discharge of the first portion of the charge and at a second rate greater than the first rate;
the capacitor having stored therein prior to the onset of the discharge of the second portion of the charge a portion of the charge sufficient to energize the other device;
wherein the portion of the circuit comprises a Zener diode connected between a terminal of the capacitor and a gate of the first transistor;
wherein the portion of the circuit further comprises at least a first resistor that is connected between the terminal of the capacitor and an electrode of the first transistor, and wherein the electrode of the first transistor is further connected with a gate of the second transistor;
wherein an electrode of the second transistor is connected with the terminal of the capacitor; and
wherein the portion of the circuit further comprises a second resistor connected with the electrode of the second transistor and with another electrode of the second transistor, the second transistor being structured to form a conductive channel between the electrode and the another electrode when a voltage to the gate of the second transistor is at or above a threshold voltage.
10. The circuit of claim 9 wherein the at least first and second resistors are of substantially equal resistance.
11. The circuit of claim 9 wherein the portion of the circuit further comprises a third resistor connected between the another electrode of the second transistor and a ground of the circuit.
12. A circuit structured to energize another device, the circuit comprising:
a capacitor structured to at least temporarily store a charge;
a portion of the circuit comprising a first solid state switch and being structured to discharge a first portion of the charge at a first rate;
another portion of the circuit comprising a second solid state switch and being structured to discharge a second portion of the charge subsequent to the discharge of the first portion of the charge and at a second rate greater than the first rate;
the capacitor having stored therein prior to the onset of the discharge of the second portion of the charge a portion of the charge sufficient to energize the other device;
wherein the portion of the circuit comprises a Zener diode connected between a terminal of the capacitor and a gate of the first transistor;
at least one of the portion of the circuit and the another portion of the circuit is structured to cause the first portion of the charge to flow through a first number of resistors;
at least one of the portion of the circuit and the another portion of the circuit is structured to cause the second portion of the charge to flow through a second number of resistors; and
the first number of resistors has a first resistance at least about one order of magnitude greater than a second resistance of the second number of resistors.
13. The circuit of claim 12 wherein a further portion of the circuit is structured to discharge a remaining portion of the charge subsequent to the discharge of the second portion of the charge and at a third rate less than the first rate.
14. The circuit of claim 1 wherein the circuit further comprises an ARM switch, the ARM switch and the FIRE switch each being independently movable between an OPEN condition and a CLOSED condition, the circuit being substantially disconnected from power sources external to the circuit when the ARM and FIRE switches are in the OPEN condition.