Covers how open-load, short-circuit, and short-to-battery faults are detected and reported, and how to distinguish between fault types on devices with a single shared fault pin versus SPI fault registers.
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Device Type |
Question |
Answer |
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HSS |
How does open-load detection work in ON-state vs OFF-state? |
In the OFF state: a weak pulled resistor is connected between VBB and VOUT; if the load path is open, the output voltage rises above a threshold and the fault flag is set. In the ON state: the device monitors output current — if current falls below a minimum threshold. During PWM switching, brief open-load conditions occur between pulses — the device's deglitch filter prevents false flags for these transients, but verify the timing window matches your PWM frequency.
Related figure: SLVAG11, Figure 3-5 “Typical Open-Load Detection Scheme Integrated Within the High-Side Switch” shows the pull-up/comparator path used to detect this fault in both states — ti.com/lit/pdf/slvag11. Sources: |
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Multiple |
How do I determine the exact type of fault when all faults pull the FLT or ST pin low? |
TI standard (GPIO-interface) HSS devices provide a fault table in the datasheet for determining the exact fault cause based on the device state and diagnostic pin outputs. Example shown below from TPS1HC04 device
SPI devices (TPS2HCS08-Q1, etc.) provide separate fault register bits, making this unambiguous. |
