ltc4270 Linear Technology Corporation, ltc4270 Datasheet - Page 7

• Manufacturer Part Number: ltc4270
• Description: 12-port Poe/poe+/ltpoe++ Pse Controller
• Manufacturer: Linear Technology Corporation

ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at T
SYMBOL PARAMETER
I
f
t
t
t
t
t
t
t
t
t
t
t
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. With the exception of (V
DGND), exposure to any Absolute Maximum Rating condition for extended
periods may affect device reliability and lifetime.
Note 2: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 140ºC when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 3: All currents into device pins are positive; all currents out of device
pins are negative.
Note 4: The LTC4270 operates with a negative supply voltage (with respect
to AGND). To avoid confusion, voltages in this data sheet are referred to in
terms of absolute magnitude.
Note 5: t
Note 6: The LTC4271 digital interface operates with respect to DGND. All
logic levels are measured with respect to DGND.
2
SCLK
1
2
3
4
5
5
6
7
8
r
f
C Timing
DIS
Clock Frequency
Bus Free Time
Start Hold Time
SCL Low Time
SCL High Time
SDAIN Data Hold Time
Data Clock to SDAOUT Valid
Data Set-Up Time
Start Set-Up Time
Stop Set-Up Time
SCL, SDAIN Rise Time
SCL, SDAIN Fall Time
Fault Present to INT Pin Low
Stop Condition to INT Pin Low
ARA to INT Pin High Time
SCL Fall to ACK Low
is the same as t
MPDO
defined by IEEE 802.3at
A
= 25°C. (Notes 3 & 4)
CONDITIONS
(Note 7)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
Figure 5 (Notes 7, 9)
(Notes 7, 9, 10)
(Notes 7, 9, 10)
(Notes 7, 9)
(Notes 7, 9)
The
DD
–
l
denotes the specifications which apply over the full operating
Note 7: Guaranteed by design, not subject to test.
Note 8: The IEEE 802.3af specification 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
Note 9: Values Measured at V
Note 10: If a fault condition occurs during an I
will not be pulled down until a stop condition is present on the I
Note 11: Load characteristics of the LTC4270 during Mark: 7V < (AGND –
V
Note 12: See the LTC4271 Software Programming documentation for
information on serial bus usage and device configuration and status
registers.
Note 13: Do not source or sink current from CAP1 and CAP2.
MPS
OUTn
within any t
) < 10V or I
MPDO
OUT
< 50μA.
time window.
LTC4270/LTC4271
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
ILD
and V
MIN
480
240
480
240
240
240
60
80
IHD
2
TYP
C transaction, the INT pin
MAX
130
120
150
130
1.5
1.5
60
1
2
C bus.
UNITS
42701f
7
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
μs
μs
ns