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AUTO MODE FUNCTIONAL DESCRIPTION
Auto Mode
TPS2384
SLUS634D – NOVEMBER 2004 – REVISED MARCH 2007
Auto mode (AM, MS = 0) operation is the basic approach for applying power to IEEE compliant PD’s. When AM
has been selected the TPS2384 automatically performs the following functions:
• Discovery of IEEE 802.3af compliant powered devices (PD's)
• Classification
• Power delivery
• Port over/under voltage detection
• Port over current detection (350 mA < I
PORT
< 400 mA
• Port maximum current limit (400 mA < I
PORT
< 450 mA)
• DC Disconnect (5 mA < I
PORT
< 10 mA)
• Thermal shutdown protection (TSD), (T
J
> 150 ° C)
• Internal oscillator watchdog
In AM the contents of all read registers are available via the I
2
C interface. In addition all control registers except
for the function bits can be written. This supports a semi-automode where the TPS2384 auto detects compliant
PD's while a host can access the A/D registers and class information and then implement power management
(including turning a port off, responding to faults, etc).
The write registers that are still active in AM are:
• All ports disable – Common Control register 0001b
• Over/Under Voltage Faults – Common Control register 0001b
• Software reset – Common Control register 0001b
• Disconnect disable – Port Control 1 register 0010b
• Discovery fault disable – Port Control 1 register 0010b
• Port enable – Port Control 2 register 0011b
For Alternative B, semi-auto mode implementations which will manipulate the all Ports Disable or Port Enable
bits, please contact the factory for additional application information.
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