VIN_UV_WARN is a standard PMBus® command for configuring or reading an 8-bit threshold for the input undervoltage warning detection. This command uses the PMBus® DIRECT format. When reading and writing to this register, use the coefficients shown in Table 8-67, Equation 19, and Equation 20 to convert between real word units and hexadecimal values. This command uses the PMBus® read or write word protocol.

Contents of this register are compared to the VIN ADC telemetry value. If the measured VIN value falls below the value in this register, the VIN_UV_WARN flags are set in the respective registers. The SMBA# signal is asserted. When the input voltage rises above the VIN_UV_WARN threshold, and the CLEAR_FAULTS command is sent afterwards, this warning flag and alert are cleared.

When an input undervoltage warning is detected, the device:

• sets the NONE_OF_THE_ABOVE/UNKNOWN bit in the STATUS_BYTE register

• sets the INPUT_STATUS bit in the upper byte of the STATUS_WORD register

• sets the VIN_UV_WARN bit in the STATUS_INPUT register

• fills-up one of the Blackbox RAM registers (if available to write) writing the event identifier as VIN_UV_WARN and relative time stamp information

• increases the Blackbox RAM address pointer in the BB_TIMER register by one (1) if it was previously less than six (6), otherwise resets to zero (0). This change in the address pointer only occurs if one of the Blackbox RAM registers is available to write.

• notifies the host by asserting SMBA#, if it is not masked setting the STATUS_IN bit in the ALERT_MASK register and the GPIO4 pin is configured as SMBA# Output in the GPIO_CONFIG_34 register