ZHCSOF7B september 2022 – june 2023 TPS25990
PRODUCTION DATA
CABLE_DROP is a manufacturer-specific command that allows configuring or reading an 8-bit reference threshold for the maximum cable voltage drop expected to implement the input cable fault detection feature. 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.
This command uses the PMBus? read or write byte protocol.
Contents of this register are compared with the difference between PSU_VOLTAGE and VIN ADC telemetry values. If this difference value exceeds the value in the CABLE_DROP register, the VIN_CABLE_FAULT flags are set in the respective registers. The SMBA# signal is asserted. When the difference between PSU_VOLTAGE and VIN ADC telemetry value falls below the CABLE_DROP threshold, and the CLEAR_FAULTS command is sent afterwards, this warning flag and alart are cleared. The details of this register are shown in Table 9-69.
| Bit | Name | Description | Minimum Value | Maximum Value | Default Value | Access |
|---|---|---|---|---|---|---|
7:0 | CABLE_DROP | Maximum cable voltage drop expected | 0x00h (0 V) | 0xFFh (4.845 V) | 0xFFh (4.845 V) | Read/Write |
When the input cable fault is detected, the device:
sets the NONE_OF_THE_ABOVE/UNKNOWN bit in the STATUS_BYTE register
sets the NONE_OF_THE_ABOVE/UNKNOWN bit in the upper byte of the STATUS_WORD register
sets the VIN_CABLE_FLT bit in the STATUS_MFR_SPECIFIC_2 register
notifies the host asserting SMBA#, if it is not masked setting the UNKNOWN bit low in the ALERT_MASK register
A write command to this register should be preceded by the MFR_WRITE_PROTECT command to unlock the device first to prevent accidental accidental/spurious writes.