# US 10,840,692 B2 · Squib circuit low side battery short protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,840,692 B2 - Document ID: US10840692B2 - Status: Granted - Kind: B2 - Application number: 15/849,481 - Filed: 2017-12-20 - Published: 2019-06-20 - Granted: 2020-11-17 - Earliest claimed: 2017-12-20 - Assignees: Veoneer US, Inc. - Applicants: Autoliv ASP, Inc. - Inventors: Vincent Colarossi; Bankim Patel - Web page: https://patentgrep.com/patent/US10840692B2 ## CPC - H02H 3/16: responsive to fault current to earth, frame or mass (with balanced or differential arrangement H02H3/26 {; monitoring earth connection H02H5/105}) - H03K 17/0822: {in field-effect transistor switches} - B60R 21/017: including arrangements for providing electric power to safety arrangements {or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves} - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - H02H 7/20: for electronic equipment (for converters H02H7/10; for electric measuring instruments G01R1/36; for DC voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08) - H02H 9/046: {responsive to excess voltage appearing at terminals of integrated circuits} - H02M 3/155: using semiconductor devices only - B60R 2021/01143: {Short circuits} - B60R 2021/01184: {Fault detection or diagnostic circuits} - H03K 19/20: characterised by logic function, e.g. AND, OR, NOR, NOT circuits (H03K19/003 - H03K19/01 take precedence) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - B60R: VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A squib driver circuit for deployment of an active safety restraint in a vehicle. The squib driver circuit may include a low side protection circuit. The low side protection circuit may include 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. The low side protection circuit may disable the low side driver after the short is detected and elapse of the predetermined period of time. The squib driver circuit may be formed on a single chip. ## Claims ### Claim 1 A squib driver circuit for deployment of an active safety restraint in a vehicle, 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 configured for communication with the active safety restraint; a low side return terminal configured for 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; and a low side short to battery voltage protection circuit configured to allow an all fire signal from the low side return terminal until a short is detected between the low side return terminal and a battery voltage for a predetermined period of time and disable the low side driver after the short is detected and elapse of the predetermined period of time, wherein the low side short to battery voltage protection circuit comprises a comparator circuit to compare a voltage at the low side return terminal to a reference voltage to determine if the low side return terminal is shorted to the battery voltage, and wherein the low side short to battery voltage protection circuit comprises a current sensor to determine if a current through the low side return terminal is above a current limit; and a timer wherein the low side short to battery voltage 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. ### Claim 2 (depends on 1) The squib driver circuit according to claim 1, further comprising a timer configured to generate a low side disable signal when the voltage at the low side return terminal exceeds the reference voltage for the predetermined period of time. ### Claim 3 (depends on 1) The squib driver circuit according to claim 1, further comprising a timer configured to generate a low side disable signal when the current exceeds the current limit for the predetermined period of time. ### Claim 4 (depends on 1) The squib driver circuit according to claim 1, wherein the low side driver comprises a low side driver transistor and a gate control circuit. ### Claim 5 (depends on 4) The squib driver circuit according to claim 4, wherein the current sensor is located between the low side driver transistor and an electrical ground. ### Claim 6 (depends on 1) The squib driver circuit according to claim 1, further comprising a serial command interface for providing an all fire signal. ### Claim 7 (depends on 1) The squib driver circuit according to claim 1, wherein a serial command interface is configured to receive a command to adjust the predetermined period of time. ### Claim 8 (depends on 1) The squib driver circuit according to claim 1, wherein the predetermined period of time is a fractional portion of a deployment time of the active safety restraint. ### Claim 9 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. ### Claim 10 (depends on 9) The squib driver circuit according to claim 9, wherein the timer is configured to generate a low side disable signal when the current exceeds the current limit and the voltage at the low side return terminal exceeds the reference voltage for the predetermined period of time. ### Claim 11 (depends on 9) The squib driver circuit according to claim 9, wherein the low side driver comprises a low side driver transistor and a gate control circuit. ### Claim 12 (depends on 11) The squib driver circuit according to claim 11, wherein a current sensor is located between the low side driver transistor and the electrical ground. ### Claim 13 (depends on 9) The squib driver circuit according to claim 9, further comprising a serial command interface for receiving an all fire signal. ### Claim 14 (depends on 9) The squib driver circuit according to claim 9, further comprising a serial command interface configured to receive a command to adjust the predetermined period of time. ### Claim 15 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.