The device provides the necessary hardware to conduct offline short circuit and open load diagnostics of the external power MOSFETs and load. This is accomplished by an integrated pull up and pull down current source on the SHx pin which connect to the external half-bridge switch-node. The offline diagnostics are controlled by the associated register bit EN_OLSC. First, the offline diagnostic mode needs to be enabled through the EN_OLSC register setting. Then the individual current sources can be enabled through the PD_SHx and PU_SHx register settings.

The voltage on the SHx pin will be continuously monitored through the internal V_DS comparators. During the diagnostic state the V_DS comparators will report the real-time voltage feedback on the SHx pin node in the SPI registers in the associated VDS_XX register status bit. When in the V_DS comparators are in diagnostic mode, the global GD SPI register bits will not report faults or warnings.

Before enabling the offline diagnostics it is recommended to place the external MOSFET half-bridges in the disabled state through the EN_GD register setting. Additionally, the V_DS comparator threshold ( or ) should be adjusted to 1-V or greater to ensure enough headroom for the internal blocking diode forward voltage drop.

Figure 7-33 Offline Diagnostics