MAX5971B Maxim Integrated Products, MAX5971B Datasheet - Page 29

• Manufacturer Part Number: MAX5971B
• Description: PSE Controller
• Manufacturer: Maxim Integrated Products

The MAX5971B continuously monitors the power sup-
plies and sets the appropriate bits in the supply event
register (R0Ah/R0Bh, Table 12). On power-up or after
a reset condition, the supply event register is set to a
default value of 00h. V
exceeds its overvoltage threshold. V
whenever V
A thermal shutdown circuit monitors the temperature
of the die and resets the MAX5971B if the temperature
exceeds +150NC. TSD is set to 1 after the MAX5971B
returns to normal operation.
When V
in reset mode and securely holds the port off. When V
rises above its UVLO threshold, the device comes out of
reset and the V
is set to 1.
Table 12. Supply Event Register
Table 13. Port Status Register
V
SYMBOL
Reserved
Reserved
Reserved
Reserved
SYMBOL
Reserved
Reserved
DET_ST
EE_UVLO
V
V
CLASS
EE_OV
EE_UV
TSD
ADDRESS =
EE
ADDRESS = 0Ch
is below its UVLO threshold, the MAX5971B is
EE
BIT NO.
BIT NO.
falls below its undervoltage threshold.
EE_UVLO
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
______________________________________________________________________________________
Supply Event Register (R0Ah/R0Bh)
EE_OV
bit in the supply event register
TYPE
TYPE
0Ah
—
—
—
—
—
—
R
R
R
R
R
R
R
R
R
R
is set to 1 whenever V
Reserved
CLASS[2]
CLASS[1]
CLASS[0]
Reserved
DET[2]
DET[1]
DET[0]
TYPE
Single-Port, 40W, IEEE 802.3af/at,
0Bh
CoR
CoR
CoR
CoR
—
—
—
—
EE_UV
Overtemperature shutdown
Reserved
Reserved
V
V
V
Reserved
Reserved
EE
EE
EE
is set to 1
undervoltage lockout condition
overvoltage condition
undervoltage condition
EE
EE
PSE Controller with I
As with any of the other event registers, the supply
event register has two addresses. When read through
the R0Ah address, the content of the register is left
unchanged. When read through the CoR R0Bh address,
the register content is reset to the default state.
The port status register (R0Ch, Table 13) records the
results of the port detection and classification at the end
of each phase in three encoded bits. On power-up or
after a reset condition, the port status register is set to a
default value of 00h. Tables 14 and 15 show the detection
and classification result decoding charts, respectively.
For CLC_EN = 0 (R23h[5]), the detection result is shown
in Table 13. When CLC_EN = 1, the MAX5971B allows
valid detection of high capacitive loads of up to 47FF, typ.
As a protection, when POFF_CL (R12h[3], Table 18) is set
to 1, the MAX5971B prohibits turning on power to the port
that returns a status 111 after classification.
DESCRIPTION
The Status Registers (R0Ch to R11h)
DESCRIPTION
Port Status Register (R0Ch)
2
C
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