max5965a Maxim Integrated Products, Inc., max5965a Datasheet - Page 35

• Manufacturer Part Number: max5965a
• Description: High-power, Quad, Monolithic, Pse Controllers For Power Over Ethernet
• Manufacturer: Maxim Integrated Products, Inc.

TSTART[1,0] (Table 20a) programs the startup timers.
Startup time is the time the port is allowed to be in cur-
rent limit during startup. TFAULT[1,0] programs the
fault time. Fault time is the time allowed for the port to
be in current limit during normal operation. RSTR[1,0]
programs the discharge rate of the TFAULT_ counter
and effectively sets the time the port remains off after
an overcurrent fault. TDISC[1,0] programs the load dis-
connect detection time. The device turns off power to
the port if it fails to provide a minimum power mainte-
nance signal for longer than the load disconnect detec-
tion time (t
Table 20a. Timing Configuration Register
Table 20b. Startup, Fault, and Load Disconnect Timer Values for Timing Register
RSTR[1]
RSTR[0]
TSTART[1]
TSTART[0]
TFAULT[1]
TFAULT[0]
TDISC[1]
TDISC[0]
(ADDRESS = 16h)
High-Power, Quad, Monolithic, PSE Controllers
SYMBOL
BIT [1:0]
00
01
10
11
DISC
).
ADDRESS = 16h
______________________________________________________________________________________
16 x t
32 x t
64 x t
0 x t
BIT
RSTR
7
6
5
4
3
2
1
0
FAULT
FAULT
FAULT
FAULT
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
t
DISC
1 / 2 x t
1 / 4 x t
2 x t
nominal (350ms, typ)
DISC
Restart timer programming bit 1
Restart timer programming bit 0
Startup timer programming bit 1
Startup timer programming bit 0
Overcurrent timer programming bit 1
Overcurrent timer programming bit 0
Load disconnect timer programming bit 1
Load disconnect timer programming bit 0
DISC
DISC
t
DISC
nominal
nominal
nominal
for Power over Ethernet
Set the bits in R16h to scale the t
t
Electrical Characteristics table.
When the MAX5965A/MAX5965B shut down a port due
to an extended overcurrent condition (either during
startup or normal operation), if RSTR_EN is set high, the
part does not allow the port to power back on before
the restart timer (Table 20b) returns to zero. This effec-
tively sets a minimum duty cycle that protects the exter-
nal MOSFET from overheating during prolonged output
overcurrent conditions. A reset sets R16h = 00h.
DISC
t
START
to a multiple of their nominal value specified in the
1 / 2 x t
2 x t
4 x t
nominal (60ms, typ)
START
START
START
t
DESCRIPTION
START
nominal
nominal
nominal
t
FAULT
1 / 2 x t
2 x t
4 x t
START
nominal (60ms, typ)
FAULT
FAULT
FAULT
t
FAULT
, t
nominal
nominal
FAULT
nominal
, and
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