7.5.8 Output Voltage Margin Testing
The TPS53681 provides several commands to enable voltage margin testing.
The upper two MARGIN bits in the OPERATION command can be used to toggle the active channel between three states:
- Margin None (MARGIN = 0000b). The output voltage target is equal to VOUT_COMMAND.
- Margin Low (MARGIN = 01xxb). The output voltage target is equal to VOUT_MARGIN_LOW.
- Margin High (MARGIN = 10xxb). The output voltage target is equal to VOUT_MARGIN_HIGH.
In order to use OPERATION, the active channel must be configured for to respect the OPERATION command, via ON_OFF_CONFIG. Output voltage transitions will occur at the slew rate defined by VOUT_TRANSITION_RATE.
The lower two MARGIN bits in the OPERATION command select overvoltage/undervoltage fault handling during margin testing:
- Ignore Faults (MARGIN = xx01b) . Overvoltage/Undervoltage faults will not trigger during margin tests.
- Act on Faults (MARGIN = xx10b). Overvoltage/Undervoltage faults will trigger during margin tests.
Example: Output Voltage Margin Testing (Ignore Faults)
- Write to the PAGE command to select the desired channel (E.g. PAGE = 00h for channel A).
- Write VOUT_COMMAND to the desired VID code during Margin None operation.
- Write VOUT_MARGIN_LOW to the desired VID code during Margin Low operation.
- Write VOUT_MARGIN_HIGH to the desired VID code during Margin High operation.
- Set the CMD bit in ON_OFF_CONFIG to 1b to ensure the device is configured to respect the OPERATION command.
- Margin None. Write OPERATION to 80h.
- Margin Low. Write OPERATION to 94h.
- Margin High. Write OPERATION to A4h.