JAJSHI3C March 2019 – October 2019 TPS23881
PRODUCTION DATA.
In autonomous mode, the TPS23881 is capable of operating without any I2C communication or host control. As in auto mode, when the device is operating in autonomous mode, the ports will be continuously cycling through discovery, and the ports will automatically power whenever a valid (defection and classification) PD is connected.
Connecting a resistor between the AUTO pin and GND based on the table below will enable autonomous mode and configure all the ports to the same Power Allocation settings. In the event a PD is connected with a higher requested class than the autonomous mode configuration, the port will power demote the PD to the selected autonomous mode configuration power level.
Auto Pin | Autonomous Mode Configuration | Resulting Register Configurations | ||
---|---|---|---|---|
0x12h | 0x14h | 0x29h | ||
Open/Floating | Disabled | 0000, 0000b | 0000, 0000b | 0000, 0000b |
124 kΩ | 2-pair 15W | 1111, 1111b | 1111, 1111b | 0000, 0000b |
62 kΩ | 2-pair 30W | 1111, 1111b | 1111, 1111b | 0011 0011b |
35.7 kΩ | 4-pair 30W | 1111, 1111b | 1111, 1111b | 1011 1011b |
22.6 kΩ | 4-pair 45W | 1111, 1111b | 1111, 1111b | 1100, 1100b |
15.8 kΩ | 4-pair 60W | 1111, 1111b | 1111, 1111b | 1101, 1101b |
11 kΩ | 4-pair 75W | 1111, 1111b | 1111, 1111b | 1110, 1110b |
7.7 kΩ | 4-pair 90W | 1111, 1111b | 1111, 1111b | 1111, 1111b |
SPACE
NOTE
A 10 nF capacitor is required in parallel with RAUTO to ensure stability in the Autonomous mode selection.
The I2C interface is still fully operational in Autonomous mode, and the all of the port telemetry and configurability is still supported
The Auto pin resistance (RAUTO) will not be measured following a device reset (assertion of the RESET pin or RESAL bit in register 0x1A). The device wil only measured (RAUTO) and pre-configure the internal registers during power up (VVPWR and VVDD rising above their respective UVLO thresholds).
NOTE
The device SRAM will need to be programmed in order to support applications that desire to remove a device from Autonomous mode after having initially powered up in Autonomous mode.
A device running from the internal ROM (SRAM unprogrammed) in Autonomous mode will turn off and automatically resume discovery and power on any valid loads following the assertion of the RESET pin, I2C register 0x1A RESAL or RESPn bits, or a mode off command. Whereas a device running in Autonomous mode with the SRAM programmed will turn off and remain inactive until the host re-enables the port(s) through the I2C bus.