This diagnostic technique was also tested by disconnecting the TMAG5328 ADJ pin from the DAC, disconnecting the TMAG5328 VCC pin from the power supply, and disconnecting the TMAG5328 OUT pin from the OUT signal probed by the logic analyzer and microcontroller.

When the ADJ pin was disconnected from the DAC, the output of the TMAG5328 was either asserted low (Figure 4-6) or high (Figure 4-7). In both cases, the TMAG5328 OUT pin did not have a square wave with frequency equal to the DAC voltage frequency, which would indicate that a fault occurred.

Figure 4-6 Logic Analyzer Screenshot of TMAG5328 OUT Pin When ADJ Pin Disconnected and TMAG5328 OUT Pin is Low.

Figure 4-7 Logic Analyzer Screenshot of TMAG5328 OUT Pin When ADJ Pin Disconnected and TMAG5328 OUT Pin is High.

When VCC was disconnected from the TMAG5328, the OUT pin was observed low, as shown in Figure 4-8. This was logged by the EVM’s microcontroller as a fault event.

Figure 4-8 Logic Analyzer Screenshot of TMAG5328 OUT Pin When VCC Disconnected.

Similarly, the OUT pin was also observed low when the TMAG5328 OUT pin was disconnected, as shown in Figure 4-9. As a result of the OUT pin being stuck low, the EVM’s microcontroller also logged this as a fault event.

Figure 4-9 Logic Analyzer Screenshot When OUT Pin Disconnected.

The TMAG5328 OUT pin did not have a square wave after VCC or OUT were disconnected, therefore this technique was able to detect these signal disconnection faults.