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.