TI TPIC71002TDCARQ1

The TPIC71002 is a dual-channel squib driver designed for airbag deployment in automotive applications. Each channel includes a high-side and low-side switch, with independent control logic provided to prevent inadvertent deployment. Both high-side and low-side switches support internal current limiting and over-temperature protection. IC registers are used for dual-channel configuration, control, and status monitoring. To prevent inadvertent deployment, the high-side and low-side switches can only be turned on when the proper configuration sequencing is applied, two independent arming safety inputs are active, and multiple inputs of the deployment controller logic meet the required levels. The registers are programmed via a serial communication interface. To avoid excessive energy consumption, the maximum operating ON time per channel is limited by a programmable ignition timer. Additionally, the current limit register can be used to program the maximum current through the switches during deployment. The current limit for the low-side switch is higher than that of the corresponding high-side switch. During deployment, the low-side switch is fully enhanced and operates in RDS_ON mode, while the high-side switch operates in current regulation mode. The IC diagnostic functions monitor deployment pin voltages to support high-side switch testing, low-side switch testing, squib driver resistance measurement, squib battery or ground leakage measurement, or leakage measurement of any squib channel. Squib leakage measurement does not require the presence of a squib load and involves the Zx and ZMx pins. Diagnostic information is communicated via the AMX_OUT pin (for analog signals) and SPI-mapped status registers (for digitally core-latched status signals). Both high-side and low-side squib drivers have diagnostic-level and deployment-level current limits. The default current limit for both high-side and low-side squib drivers is the diagnostic-level current limit. The high-side switch deployment current limit for all high-side drivers can be set to 1.2 A (minimum) or 1.75 A (minimum) via SPI-mapped registers and device EEPROM settings. The low-side deployment current limit is not programmable and is fixed at a level greater than that of the high-side driver current limit. The ON duration for each individual squib driver can be programmed via SPI-mapped registers. Deployment sequencing requires a specific combination of software commands and external hardware safety interlock logic inputs (TZ=H, IWD=L) to enable deployment functionality. The turn-on sequencing of the high-side and low-side drivers can be software-controlled via SPI commands. The turn-off sequence for the high-side driver can be automatically controlled by the deployment ASIC, while the low-side driver turn-off sequence can be controlled by the deployment ASIC or software-controlled via SPI commands. After the programmed ON time has elapsed, the high-side driver turns off first, followed by the low-side driver approximately 100 µs later (for hardware-controlled turn-off sequencing device configurations), or after an SPI command when the external microprocessor has been receiving the low-side driver turn-off information (for software-controlled turn-off sequencing device configurations). RESET_N is an active-low input reset signal. Once the external supply voltage is within specified limits, this input is driven high (by the power supply unit and/or external µc). An external microprocessor is required to configure and control the device via the serial communication interface. Reliable software is critical to proper system operation.

• Dual-channel squib driver for airbag applications
• Loop diagnostic monitoring with two logic inputs providing independent safety logic for deployment enable/disable
• Two independent thermal-protected high-side drivers capable of sourcing deployment or diagnostic current levels to each squib load
• Two independent overvoltage- and thermal-protected low-side drivers capable of sinking deployment or diagnostic current levels from each squib load
• 1.2 A/1.75 A firing current per output, typically for 2 ms/0.5 ms
• SPI slave interface supporting serial bus communication with parity
• Firing VZx voltage range: 10 V to 35 V, with transient voltage up to 40 V
• Programmable firing time up to 8.2 ms
• Register-based common load current settings for all deployment loops
• Per-deployment-loop register-configurable individual firing current timer
• Firing current timer limiting to monitor deployment time firing current for each deployment loop
• Independent switching control for high-side and low-side switches
• Fault detection diagnostic mode
• Internal fault monitoring for safe operation
• Multiplexed output buffer supporting analog voltage measurement
• External clamp device on squib pins; no protection required against substrate injection effects from dynamic short-to-ground during deployment
• Ratiometric squib resistance measurement achievable when deployment ASIC external pins are connected to microprocessor ADC supply
• All pins except GNDx, AGND, DGND, VCC5, VDDIO, and AMX_OUT support 40 V pin capability
• Operating ambient temperature range: -40°C to 105°C
• Thermally enhanced 48-pin TSSOP DCA PowerPad package

• Squib driver for airbag applications