This reference design also provides diagnostic coverage for detecting various faults which helps in increasing safe failure fraction.
This design uses ISO1212 as an isolated 24-V digital input receiver, compliant to IEC 61131-2 Type 1 characteristics to accept the two STO signals. Unlike traditional optocoupler solutions with discrete components having imprecise current limiting circuitry, the ISO1212 devices provide a simple, low-power solution with accurate current limits and a longer lifespan.
The adjustable current-limit function of the load switch improves the reliability of the system. The ready pin of the gate driver, ISO5852S, helps in monitoring the supply rails.
Features
- Implements safe torque off (STO) to accomplish the Stop Category 0 specified in IEC 61800-5-2.
- Dual channel STO signals with multiple options for preventing generation of torque in the motor:
- Disconnect power from the gate driver IC (both on low voltage and high voltage domains).
- Generation of hardware trip signals to the terminate the PWM generation inside the MCU.
- Self-diagnostics coverage which includes monitoring safety pulses and detecting various faults within the circuit.
- ±60-V input tolerance with reverse polarity protection helps ensure STO pins are protected in case of faults.
- Accurate output current monitoring by the high side smart switch.
- Detection of input and output under-voltage lockout (UVLO) of the gate driver with ready (RDY) pin indication.
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