LTC4263-1
4
42631fa
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Timing Characteristics
t
DET
Detection Time Beginning to End of Detection
l
270 290 310 ms
t
DETDLY
Detection Delay PD Insertion to Detection Complete
l
300 620 ms
t
PON
Power Turn-On Delay End of Valid Detect to Application of Power
l
135 145 155 ms
t
RISE
Turn-On Rise Time V
DD48
– V
OUT
: 10% to 90%
C
PSE
= 0.1μF
l
40 170 μs
t
OVLD
Overload/Short-Circuit Time Limit
l
52 62 72 ms
t
ED
Error Delay I
CUT
Fault to Next Detect
l
3.8 4.0 4.2 s
t
MPDO
Maintain Power Signature (MPS)
Disconnect Delay
PD Removal to Power Removal
l
320 350 380 ms
t
MPS
MPS Minimum Pulse Width PD Minimum Current Pulse Width
Required to Stay Connected (Note 9)
l
20 ms
t
DBO
Midspan Mode Detection Backoff
R
PORT
= 15.5kΩ
l
3.0 3.2 3.4 s
t
DISDLY
Power Removal Detection Delay
l
0.8 0.95 1.1 s
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
DD48
– V
SS
= 48V and V
DD5
not driven externally. All voltages are
relative to V
SS
unless otherwise noted. (Note 2, Note 5)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to V
SS
unless otherwise
specifi ed.
Note 3: 80mA of current may be pulled from the OUT or ACOUT pin
without damage whether the LTC4263-1 is powered or not. These pins will
also withstand a positive voltage of V
SS
+ 80V.
Note 4: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specifi ed maximum operating junction
temperature may impair device reliability.
Note 5: The LTC4263-1 operates with a negative supply voltage. To avoid
confusion, voltages in this data sheet are referred to in terms of absolute
magnitude.
Note 6: In order to reduce power dissipated in the switch while charging
the PD, the LTC4263-1 reduces the current limit when V
OUT
– V
SS
is large.
Refer to the Typical Performance Characteristics for more information.
Note 7: The LTC4263-1 includes a high-speed current limit circuit
intended to protect against faults. The fault protection is activated
for port current in excess of I
FAULT
. After the high-speed current limit
activates, the short-circuit current limit (I
LIM
) engages and restricts
current to IEEE 802.3af levels.
Note 8: The LTC4263-1 digital interface operates with respect to V
SS
.
All logic levels are measured with respect to V
SS
.
Note 9: The IEEE 802.3af specifi cation allows a PD to present its
Maintain Power Signature (MPS) on an intermittent basis without being
disconnected. In order to stay powered, the PD must present the MPS for
t
MPS
within any t
MPDO
time window.
