In the absence of an input signal to the DH pin, regardless of whether DGND and PGND are common, regardless of DISABLE=0 or DISABLE=1, both VOA and GNDA have an output voltage of approximately 11.5V. Is this a normal phenomenon?
This is not normal operation. The default state of the VOA to GNDA connection is low. One test you could perform is to power 12VM, but don't power 5VD. If VOA to GNDA still has 11.5 V, there is a problem with the gate driver IC.
When the DISABLE pin is brought high, both VOA/GNDA and VOB/GNDB will be set to their low output states.
After rethinking about your question, are you measuring from VOA to PGND? If so, when the half-bridge is not actively switching, the bootstrap configuration will not be charging the VDDA/GNDA bootstrap capacitor. The voltage between GNDA and PGND will be whatever the half-bridge center node is at. When VOB is high, the lowside of the bootstrap should turn on, bringing GNDA to PGND.
If you are testing the circuit without the half-bridge MOSFETs, then I would expect GNDA to be pulled up to almost 12 V, and what you are seeing is expected. Putting in the half-bridge MOSFETs and operating the circuit with a PWM signal will periodically bring GNDA to PGND.
Be careful with a single ended probe when measuring VOA to GNDA. Since the GNDA is the midpoint of the half-bridge, scope ground will be pulled to whatever the half-bridge does.
Hi RSchnell，I understand what you mean. thank you for your help.