TPS2388 Datasheet, PDF (5/82 Pages) Texas Instruments – IEEE 802.3at 8-Channel Power-over-Ethernet PSE Controller

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TPS2388
SLUSC25A – FEBRUARY 2015 – REVISED AUGUST 2017
Detailed Pin Description (continued)
Each KSENS is shared between two neighbor SEN pins as following: KSENSA with SEN1 and SEN2, KSENSB
with SEN3 and SEN4, KSENSC with SEN5 and SEN6, KSENSD with SEN7 and SEN8. To optimize the
accuracy of the measurement, take care with the PCB layout to minimize the impact of the PCB traces'
resistance.
OSS: Fast shutdown, active high. This pin is internally pulled down to DGND, with an internal 1-µs to 5-µs
deglitch filter.
The Port Power Priority/ICUT Disable register is used to determine which port is shut down in response to an
external assertion of the OSS fast shutdown signal. The turn off procedure is similar to a port reset using Reset
command (1Ah register).
RESET: Reset input, active low. When asserted, the TPS2388 resets, turning off all ports and forcing the
registers to their power-up state. This pin is internally pulled up to VDD, with internal 1-µs to 5-µs deglitch filter.
The designer can use an external RC network to delay the turn-on. There is also an internal power-on-reset
which is independent of the RESET input.
NOTE
During the first 5 ms after RESET has been asserted, if a port is turned on using the
Power Enable command (0x19), TI recommends to wait for the expiration of that 5-ms
initial period before sending any subsequent Detect/Class Restart or Detect/Class Enable
command.
SCL: Serial clock input for I²C bus.
SDAI: Serial data input for I²C bus. This pin can be connected to SDAO for non-isolated systems.
SDAO: Open-drain I²C bus output data line. Requires an external resistive pull-up. The TPS2388 uses separate
SDAO and SDAI lines to allow optoisolated I²C interface. SDAO can be connected to SDAI for non-isolated
systems.
A4-A1: I²C bus address inputs. These pins are internally pulled up to VDD. See Pin Status Register for more
details.
SEN1-8: Port current sense input relative to KSENSn (see KSENSn description). A differential measurement is
performed using KSENSA-D Kelvin point connection. Monitors the external MOSFET current by use of a 0.255-Ω
current sense resistor connected to DGND. Used by current foldback engine and also during classification. Can
be used to perform load current monitoring via A/D conversion.
Note that a classification is done while using the external MOSFET so that doing a classification on more than
one port at same time is possible without overdissipation in the TPS2388. For the current limit with foldback
function, there is an internal 2-µS analog filter on the SEN1-8 pins to provide glitch filtering. For measurements
through an A/D converter, an anti-aliasing filter is present on the SEN1-8 pins. This includes the port-powered
current monitoring, port policing, and DC disconnect.
If the port is not used, tie SENn to AGND.
VDD: 3.3-V logic power supply input.
VPWR: High voltage power supply input. Nominally 48 V.
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