MAX5971BETI+ Maxim Integrated Products, MAX5971BETI+ Datasheet - Page 40

• Manufacturer Part Number: MAX5971BETI+
• Description: Hot Swap & Power Distribution IEEE 802.3af/at PSE Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX5971BETI+

• Lead Free Status / Rohs Status: Details

Single-Port, 40W, IEEE 802.3af/at,
PSE Controller with I
The port current registers (R30h to R31h, Tables 38 and
39) provide port current readout during classification
and normal power mode. On a power-up or after a reset
condition, these registers are both set to a default value
of 0x00h. The port current readout has 9 bits of overall
resolution. The MAX5971B has 8-bit registers, so the
data is split between 2 consecutive registers. R30h[7:0]
contains the highest 8 bits (MSB) and R31h[0] contains
the lowest bit (LSB). To avoid the LSB register changing
while reading the MSB, the register contents are frozen if
the addressing byte points to either of the current read-
out registers.
Table 38. Port Current Register (MSB)
Table 39. Port Current Register (LSB)
40
SYMBOL
SYMBOL
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
IPD
IPD
_____________________________________________________________________________________
ADDRESS = 30h
ADDRESS = 31h
BIT NO.
BIT NO.
Port Current Registers (R30h to R31h)
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Current Readout Registers
R/W
R/W
—
—
—
—
—
—
—
R
R
R
R
R
R
R
R
R
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
IPD[0] (LSB)
IPD[8] (MSB)
IPD[7]
IPD[6]
IPD[5]
IPD[4]
IPD[3]
IPD[2]
IPD[1]
(R30h to R37h)
2
C
When the port is powered, the port output current can
be calculated as:
During classification, the port current is:
where N
readout. The ADC saturates both at full scale and at
zero, resulting in poor current readout accuracy near the
top and bottom codes.
Registers R32h to R37h are unconnected; writing to them
has no effect (address autoincrement still functions) and
a read always returns logical zeros.
DESCRIPTION
DESCRIPTION
IPD
is the decimal value of the 9-bit port current
I
CLASS
I
OUT
Reserved Registers (R32h to R37h)
= N
= N
IPD
IPD
x 0.0975mA
x 2.95mA