_______________________________________________________________________________________ 5
MAX5971B
Single-Port, 40W, IEEE 802.3af/at,
PSE Controller with I
2
C
ELECTRICAL CHARACTERISTICS (continued)
(V
AGND
- V
EE
= 32V to 60V, T
A
= -40NC to +85NC, all voltages are referenced to V
EE
, unless otherwise noted. Typical values are at
V
AGND
- V
EE
= +54V, T
A
= +25NC. Currents are positive when entering the pin and negative otherwise.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Classification Current Thresholds I
CL
Classification current
thresholds between
classes
Class 0, Class 1 5.5 6.5 7.5
mA
Class 1, Class 2 13.0 14.5 16.0
Class 2, Class 3 21 23 25
Class 3, Class 4 31 33 35
Class 4 upper limit
(Note 7)
45 48 51
Mark Event Voltage V
MARK
V
AGND
- V
DET
during mark event 8 10 V
Mark Event Current Limit
IMARK_LIM
V
DET
= V
AGND
during mark event measure
current through DET
55 80 mA
DIGITAL INPUTS/OUTPUTS (Voltages Referenced to V
EE
)
Digital Input Low V
IL
0.8 V
Digital Input High V
IH
2.4 V
Internal Input Pullup Current I
PU
Pullup current to internal digital supply to
set default values
3 5 7
FA
Open-Drain Output Low Voltage V
OL
I
SINK = 10mA
0.4 V
Open-Drain Leakage I
OL
Open-drain high impedance 2
FA
LED Output Low Voltage V
LED_LOW
I
LED
= 10mA, PWM disabled, port power-on 0.8 V
LED Output Leakage I
LED_LEAK
PWM disabled, shutdown mode,
V
LED
= 60V
10
FA
PWM Frequency 25 kHz
PWM Duty Cycle 6.25 %
TIMING
Startup Time t
START
Time during which a current limit set to
420mA is allowed, starts when power is
turned on (Note 8)
50 60 70 ms
Fault Time t
FAULT
Maximum allowed time for an overcurrent
condition set by I
CUT
after startup (Note 8)
50 60 70 ms
Detection Reset Time t
ME
Time allowed for the port voltage to reset
before detection starts
80 90 ms
Detection Time t
DET
Maximum time allowed before detection is
completed
330 ms
Midspan Mode Detection Delay t
DMID
2 2.2 2.4 s
Classification Time t
CLASS
Time allowed for classification 19 23 ms
Mark Event Time Time allowed for mark event 7 9 11 ms
V
EEUVLO
Turn-On Delay t
DLY
Time V
AGND
must be above the V
EEUVLO
thresholds before the device operates
5.2 ms
Restart Timer t
RESTART
Time the device waits before turning on
after an overcurrent fault (Note 8)
16 x
t
FAULT
ms
Watchdog Clock Period Rate of decrement of the watchdog time 164 ms
(15 paginas)
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