Squib circuit low side battery short protection

A squib driver circuit for deployment of an active safety restraint in a vehicle, the vehicle having an electrical ground and a battery with a battery voltage, the squib driver circuit being an integrated circuit formed on a single chip comprising:

• an input terminal for receiving an input voltage used to fire the active safety restraint;
• a high side driver configured to supply current from the input terminal to the active safety restraint;
• a low side driver configured to supply current from the active safety restraint to the electrical ground;
• and
• a low side protection circuit comprising a comparator circuit to compare a voltage at a low side return terminal to a reference voltage and activate a timer in response to the voltage at the low side return terminal exceeding the reference voltage, the timer generating a disable signal to disable the low side driver after a predetermined period of time, wherein the low side protection circuit comprises a current sensor to determine if a current through the low side driver is above a current limit;
• and
• wherein the low side protection circuit receives a low side enable signal, and the timer is activated to count when all of the low side enable signal is active and current exceeds the current limit and the voltage at the low side return terminal exceeds the reference voltage.

A squib driver circuit for deployment of an active safety restraint in a vehicle, the vehicle having an electrical ground and a battery with a battery voltage, the squib driver circuit being an integrated circuit formed on a single chip comprising:

• an input terminal for receiving an input voltage used to fire the active safety restraint;
• a high side feed terminal in communication with the active safety restraint;
• a low side return terminal in communication with the active safety restraint;
• a high side driver configured to supply current from the input terminal to the high side feed terminal;
• a low side driver configured to supply current from the low side return terminal to the electrical ground;
• a low side short to battery voltage protection circuit configured to allow an all fire signal from the low side return terminal until a first short is detected between the low side return terminal and the battery voltage for a first predetermined period of time and disable the low side driver after the first short is detected and elapse of the first predetermined period of time;
• and
• at least one of:
• a high side short to battery voltage protection circuit configured to allow an all fire signal from the high side feed terminal until a second short is detected between the high side feed terminal and the battery voltage for a second predetermined period of time and disable the high side driver after the second short is detected between and elapse of the second predetermined period of time;
• and
• a high side short to ground protection circuit configured to allow an all fire signal from the high side feed terminal until a third short is detected between the high side feed terminal and the electrical ground for a third predetermined period of time and disable the high side driver after the third short is detected and elapse of the third predetermined period of time.