Understanding Smart Sensors - Nomads.usp

260 Understanding Smart SensorsTable 11.1Fault Diagnostics for the OutputFaultTechnique1. Open load (on-state) Logic comparison2. Open load (on- or off-state) Logic comparison3. Shorted load Overcurrent sensing4. Overvoltage (load dump) Overvoltage sensing5. Overtemperature (single output) Temperature sensing6. Independent overtemperature Temperature sensing6. (multiple output)7. Solenoid movement Bipolar + logicFault-reporting techniques and corresponding MCU commands to thesmart-power IC can be accomplished by several methods. For new devices,the most appropriate communication technique is dictated by the applicationrequirements. Table 11.2 summarizes the communication techniques that areavailable as building blocks [2].For distributed control systems, both smart-sensing and smart-powernodes are required. Smart-power ICs combined with an MCU or MCUs withintegrated power devices implement the load control. That means the power oroutput side of the system must also be able to communicate using the systemprotocol. The protocols discussed in Chapter 6 must take into account theTable 11.2Summary of Communication Techniques for Power ICsParameter Communication CapabilityInputDiagnosticParallelSerialParallel/serialFlag (single)Flag (single)SerialFlag (multiple with interrupt)Within slew rate (typ ≤ 1A/ms)2-MHz SPISelectable/mixedOpen/shorted loadOpen (on- or off-state)/shorted load2-MHz SPI (all faults)Reports all faults