ZHCSCE7I March 2014 – July 2019 TPS23861
PRODUCTION DATA.
Command = 16h with 1 Data Byte, R/W
| BITS | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
|---|---|---|---|---|---|---|---|---|
| BIT NAME | TLIM | TSTART | TICUT | TDIS | ||||
| RESET or POR VALUE | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
These bits define the timing configuration for all four ports.
NOTE
The PGn and PEn bits in the Power Status Register are cleared when there is a Start, ICUT or ILIM condition.
Bit Descriptions
TLIM[1:0]: ILIM fault timing, which is the foldback current limit time duration before port turn off. This timer is loaded with its maximum count corresponding to tLIM after expiration of the tSTART period; the timer counts down when the port is limiting its output current to ILIM. If the ILIM timer counts down to zero, the port is powered off. After the port is powered off the cool-down period commences. The cool-down period is selected by the CLDN field in the Cool Down/Gate Drive register. During the cool-down period the port will not engage in detection, classification, or powered-up operation. When the port is powered up and while the port current is below ILIM, the same counter increments at a rate 1/16th of the count-down rate (independent of the setting in the CLDN field). The counter does not increment past the maximum count corresponding to the programmed TLIM value.
NOTE
At the end of the cool-down period, when in Semi-Auto or Auto Mode, a detection cycle is automatically restarted if the detect enable bit is set.
NOTE
If ILIM and ICUT are set to same value, it is a race condition between ILIM and ICUT in TPS23861 and it depends on the firmware as to the winner.
When a POEPn bit in the PoE Plus Register is cleared, the tLIM used for the associated port is always the nominal value (~60 ms). If the POEPn bit is set, then tLIM for associated port is programmable with the following selection:
| TLIM[1:0] | NOMINAL tLIM (ms) WHEN PoEPn BIT IS SET |
|---|---|
| 00 | 60 |
| 01 | 30 |
| 10 | 15 |
| 11 | 10 |
TSTART[1:0]: This 2-bit field sets the length of the tSTART period, which is the maximum allowed overcurrent time during inrush. If at the end of the tSTART period the current is still limited to IINRUSH , the port is powered off. This is followed by a cool-down period, set with the CLDN field in the Cool Down/Gate Drive Register, during which the port cannot be turned on if in Semi-Auto or Auto Mode.
NOTE
At the end of cool-down cycle, when in Semi-Auto or Auto Mode, a detection cycle is automatically restarted if the class and detect enable bits are set.
The selection is as following:
| TSTART [1:0] | NOMINAL tSTART (ms) |
|---|---|
| 00 | 60 |
| 01 | 30 |
| 10 | 120 |
| 11 | Reserved |
TICUT[1:0]: ICUT fault timing, which is the overcurrent time duration before port turn off (tOVLD).
This timer is loaded with its maximum count corresponding to tOVLD after expiration of the tSTART period; the timer counts down when the port current exceeds ICUT. If the ICUT timer counts down to zero, the port is powered off. After the port is powered off the cool-down period commences. The cool-down period is set with the CLDN field in the Cool Down/Gate Drive Register. During the cool-down period the port will not engage in detection, classification, or powered-up operation. When the port is powered up and while the port current is below ICUT, the same counter increments at a rate 1/16th of the count-down rate (independent of the setting in the CLDN field). The counter does not increment past the maximum count corresponding to the programmed TICUT value.
NOTE
At the end of cool-down cycle, when in Semi-Auto or Auto Mode, a detection cycle is automatically restarted if the detect enable bit is set.
NOTE
If ILIM and ICUT are set to same value, it is a race condition between ILIM and ICUT in TPS23861 and it depends on the firmware as to the winner.
The selection is as following:
| TICUT[1:0] | NOMINAL tOVLD (ms) |
|---|---|
| 00 | 60 |
| 01 | 30 |
| 10 | 120 |
| 11 | 240 |
TDIS[1:0]: Disconnect delay, which is the time to turn off a port once there is a disconnect condition.
After port power on and the completion of the tSTART period the TDIS counter is started when the port current drops below the disconnect threshold established in the DCTHn fields, and the counter is reset each time the current goes continuously higher than the disconnect threshold for 13% of tMPDO. The counter does not decrement below zero. The selection is as following:
| TDIS[1:0] | NOMINAL tMPDO (ms) | |
|---|---|---|
| 0 | 0 | 360 |
| 0 | 1 | 90 |
| 1 | 0 | 180 |
| 1 | 1 | 720 |