SLUSD53G March 2018 – August 2020 TPS23880
PRODUCTION DATA
COMMAND = 2Dh with 1 Data Byte, Read/Write
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
NLM34 | NLM12 | NCT34 | NCT12 | 4PPCT34 | 4PPCT12 | DCDT34 | DCDT12 |
R/W-0 | R/W-0 | R/W-0 | R/W-0 | R/W-0 | R/W-0 | R/W-0 | R/W-0 |
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset |
Bit | Field | Type | Reset | Description |
---|---|---|---|---|
7 , 6 | NLMnn | R/W | 0 | 4-Pair ILIM Fault Management bits
1 = Both channels on a 4-Pair wired port will be disabled if an ILIM fault occurs on either channel 0 = Only the channel on which the ILIM fault occurred will be disabled. The alterative channel will remain powered. In Auto mode these bits will be automatically set after turn on if a 4-Pair Single Signature device is powered |
5 , 4 | NCTnn | R/W | 0 | 4-Pair PCUT Fault Management bits
1 = Both channels on a 4-Pair wired port will be disabled if a 2-Pair PCUT fault occurs on either channel 0 = Only the channel on which the 2-Pair PCUT fault occurred will be disabled. The alterative channel will remain powered. In Auto mode these bits will be automatically set after turn on if a 4-Pair Single Signature device is powered |
3, 2 | 4PPCTnn | R/W | 0 | 4-Pair Summed PCUT Enable bits
1 = Summed 4-Pair PCut is enabled 0 = Summed 4-Pair PCut is disabled The hardware continue to monitor for ILIM faults independent of these bits In either Auto and Semi Auto modes, these bits will be automatically set to a "1" after turn on if a 4-Pair Single Signature device is powered |
1 , 0 | DCDTnn | R/W | 0 | DC Disconnect Threshold bits
1 = DC disconnect Threshold set to 4.5mA typical 0 = DC disconnect Threshold set to 6.5mA typical For 4-pair Dual Signature PDs, the DCDTxx bit will be set to “1” during turn on and the disconnect threshold will be applied independently per Channel. Thus, if either channel falls below the 4.5mA threshold for the duration of TMPDO + TMPS, only that channel will be disabled while the alternative channel remains powered as long it it satisfies. For 4-pair single signature PDs (see register 0x1Ch), these bits are internally set during power on based on the assigned class (0x4C-4F): Assigned Classes 1-4: DCDTxx = 0 Assigned Classes 5-8: DCDTxx = 1 |
Partial Disconnect: For 4-pair single signature PDs with DCDTxx = 0 and an Assigned Class = 0-4, one pair set/channel will be immediately disabled when either channel falls below the DC Disconnect threshold to improve the low current measurement accuracy. The second channel will remain powered as long as the current drawn by the load satisfies the MPS timing and current requirements. The disabled channel will be re-enabled when the single channel current increases above 75 mA.
4-pair Pcut is disabled whenever a 4-pair port is either in a partial disconnect state or one or both channel currents are below 30mA (typ).
For 4-pair single signature PDs with DCDTxx = 1 and an Assigned Class = 5-8, both channels will remain powered until the current on both channels fall below the 4.5mA threshold for the duration of TMPDO + TMPS.
Setting DCDTxx = “0” for a 4P Dual Signature PD or 4P Single Signature PD with assigned class = 5-8 after turn on will result in the use of the 6.5mA threshold per channel which is non-compliant to the 802.3bt standard.
For 4-pair Dual Signature PDs,the disconnect threshold will be applied independently per channel. Thus, if either channel falls below the disconnect threshold for the duration of TMPDO + TMPS, only that channel will be disabled while the alternative channel remains powered as long it continues to satisfy the MPS timing and current requirements.
DC Disconnect for 4-Pair ports power on in Manual/Diagnostic mode will behave as independent channels. Thus, if either channel current falls below VIMIN for longer than tMPDO , that channel will be disabled and a disconnect fault will be set (DISFn bits in register 0x06/7).