19-3412; Rev 3; 5/07
Quad Network Power Controller
for Power-Over-LAN
General Description
The MAX5935 quad network power controller is designed
for use in IEEE 802.3af-compliant power sourcing equip-
ment (PSE). The device provides power devices (PD) dis-
covery, classification, current limit, and both DC and AC
load disconnect detections. The MAX5935 can be used
in either endpoint PSE (LAN switches/routers) or midspan
PSE (power injector) applications.
The MAX5935 can operate autonomously or be con-
trolled by software through an I
2
C-compatible interface.
Separate input and output data lines (SDAIN and
SDAOUT) allow usage with optocouplers. The
MAX5935 is a slave device. Its four address inputs
allow 16 unique MAX5935 addresses. A separate
INT
output and four independent shutdown inputs (SHD_)
allow fast response from a fault to port shutdown. A
RESET
input allows hardware reset of the device. A
special Watchdog feature allows the hardware to
gracefully take over control if the software crashes. A
cadence timing feature allows the MAX5935 to be used
in midspan systems.
The MAX5935 is fully software configurable and program-
mable. A class-over-current detection function enables
system power management to detect if a PD draws more
current than the allowable amount for its class. Other fea-
tures are input under/overvoltage lockout, overtempera-
ture protection, output voltage slew-rate limit during
startup, power-good, and fault status. The MAX5935’s
programmability includes gate charging current, current-
limit threshold, startup timeout, overcurrent timeout,
autorestart duty cycle, PD disconnect AC detection
threshold, and PD disconnect detection timeout.
The MAX5935 is available in a 36-pin SSOP package
and is rated for both extended (-40°C to +85°C) and
commercial (0°C to +70°C) temperature ranges.
Features
♦
IEEE 802.3af Compliant
♦
Controls Four Independent, -48V-Powered
Ethernet Ports in Either Endpoint or Midspan PSE
Applications
♦
Wide Digital Power Input, V
DIG
, Common-Mode
Range: V
EE
to (AGND + 7.7V)
♦
PD Violation of Class Current Protection
♦
PD Detection and Classification
♦
Provides Both DC and AC Load Removal
Detections
♦
I
2
C-Compatible, 3-Wire Serial Interface
♦
Fully Programmable and Configurable Operation
Through I
2
C Interface
♦
Current Foldback and Duty-Cycle-
Controlled/Programmable Current Limit
♦
Short-Circuit Protection with Fast Gate Pulldown
♦
Direct Fast Shutdown Control Capability
♦
Programmable Direct Interrupt Output
♦
Watchdog Mode Enable Hardware Graceful
Takeover
MAX5935
Ordering Information
PART
MAX5935CAX
MAX5935CAX+
MAX5935EAX
MAX5935EAX+
TEMP RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
36 SSOP
36 SSOP
36 SSOP
36 SSOP
PKG
CODE
A36-2
A36-2
A36-2
A36-2
Pin Configuration
TOP VIEW
RESET
1
2
3
4
5
6
7
8
9
36 OSC_IN
35 AUTO
34 OUT1
33 GATE1
32 SENSE1
MIDSPAN
INT
Applications
Power-Sourcing Equipment (PSE)
Power-Over-LAN/Power-Over-Ethernet
Switches/Routers
Midspan Power Injectors
SCL
SDAOUT
SDAIN
A3
A2
A1
MAX5935
31 OUT2
30 GATE2
29 SENSE2
28 V
EE
27 OUT3
26 GATE3
25 SENSE3
24 OUT4
23 GATE4
22 SENSE4
21 AGND
20 SHD4
19 SHD3
A0 10
DET1 11
DET2 12
DET3 13
DET4 14
DGND 15
V
DD
16
SHD1 17
Typical Operating Circuits appear at end of data sheet.
SHD2 18
SSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Quad Network Power Controller
for Power-Over-LAN
MAX5935
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to V
EE
, unless otherwise noted.)
AGND, DGND, DET_, V
DD
,
RESET,
A3, A2, A1, A0,
SHD_,
OSC_IN, SCL, SDAIN, OUT_ and AUTO............-0.3V to +80V
GATE_ (Internally Clamped, Note 1) ...................-0.3V to +11.4V
SENSE_ ..................................................................-0.3V to +24V
V
DD
,
RESET,
A3, A2, A1, A0,
SHD_,
OSC_IN, SCL, SDAIN and
AUTO to DGND ....................................................-0.3V to +7V
INT
and SDAOUT to DGND....................................-0.3V to +12V
Maximum Current into
INT,
SDAOUT, DET_ .......................80mA
Maximum Power Dissipation
36-Pin SSOP (derate 11.4mW/°C above +70°C) .........941mW
Operating Temperature Ranges:
MAX5935EAX ..................................................-40°C to +85°C
MAX5935CAX .....................................................0°C to +70°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(AGND = +48V. V
EE
= 0V, V
DD
to DGND = +3.3V. All voltages are referenced to V
EE
, unless otherwise noted. Typical
values are at AGND = +48V, DGND = +48V, V
DD
= (DGND + 3.3V), T
A
= +25°C. Currents are positive when entering the pin and
negative otherwise.)
PARAMETER
POWER SUPPLIES
V
AGND
Operating Voltage Range
V
DGND
V
DD
V
DD
to V
DGND
, V
DGND
= V
AGND
V
DD
to V
DGND
, V
DGND
= V
EE
OUT_= V
EE
, SENSE_ = V
EE
, DET_ = AGND,
all logic inputs open, SCL = SDAIN = V
DD
,
INT
and SDAOUT open; measured at AGND
in power mode after GATE_ pullup
All logic inputs high, measured at V
DD
Power mode, gate drive-on, V
GATE
= V
EE
(Note 2)
SHD_
= DGND, V
GATE_
= V
EE
+ 5V
V
SENSE
= 1V, V
GATE_
= V
EE
+ 2V
V
GATE
- V
EE
, power mode, gate drive-on
Maximum V
SENSE_
allowed during current limit,
V
OUT_
= V
EE
(Note 3)
Overcurrent V
SENSE_
threshold allowed for
t
≤
t
FAULT
after startup;
V
OUT_
= V
EE
Default, Class 0,
Class 3, Class 4
Class 1
Class 2
9
-35
25
V
AGND
- V
EE
32
0
1.71
3.0
60
60
5.50
5.5
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Currents
I
EE
4.2
6.8
mA
I
DIG
GATE DRIVER AND CLAMPING
GATE_ Pullup Current
Weak GATE_ Pulldown Current
Maximum Pulldown Current
External Gate Drive
CURRENT LIMIT
Current-Limit Clamp Voltage
V
SU_LIM
I
PU
I
PDW
I
PDS
V
GS
2.7
-50
40
100
10
5.6
-65
55
11
µA
µA
mA
V
202
177
48
89
212
222
196
61
105
mV
Overcurrent Threshold After
Startup
V
FLT_LIM
mV
Foldback Initial OUT_ Voltage
Foldback Final OUT_ Voltage
V
FLBK_ST
V
FLBK_END
V
OUT_
- V
EE
, above which the current-limit trip
voltage starts folding back
V
OUT_
- V
EE
, above which the current-limit trip
voltage reaches V
TH_FB
30
50
V
V
2
_______________________________________________________________________________________
Quad Network Power Controller
for Power-Over-LAN
ELECTRICAL CHARACTERISTICS (continued)
(AGND = +48V. V
EE
= 0V, V
DD
to DGND = +3.3V. All voltages are referenced to V
EE
, unless otherwise noted. Typical
values are at AGND = +48V, DGND = +48V, V
DD
= (DGND + 3.3V), T
A
= +25°C. Currents are positive when entering the pin and
negative otherwise.)
PARAMETER
Minimum Foldback Current-
Limit Threshold
SENSE_ Input Bias Current
SUPPLY MONITORS
V
EE
Undervoltage Lockout
V
EE
Undervoltage-Lockout
Hysteresis
V
EE
Overvoltage
V
EE
Overvoltage Hysteresis
V
EE
Undervoltage
V
DD
Overvoltage
V
DD
Undervoltage
V
DD
Undervoltage Lockout
V
DD
Undervoltage-Lockout
Hysteresis
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
OUTPUT MONITOR
OUT_ Input Current
Idle Pullup Current at OUT_
PGOOD High Threshold
PGOOD Hysteresis
PGOOD Low-to-High Glitch
Filter
LOAD DISCONNECT
DC Load Disconnect
Threshold
V
DCTH
Minimum V
SENSE
allowed before disconnect (DC
disconnect active), V
OUT_
= V
EE
2.5
4
5
mV
I
BOUT
I
DIS
PG
TH
PG
HYS
t
PGOOD
Minimum time PGOOD has to be high to set bit in
register 10h
V
OUT
= V
AGND
, all modes
OUT_ discharge current, detection and
classification off, port shutdown,
V
OUT_
= V
AGND
- 2.8V
V
OUT_
- V
EE
, OUT_ decreasing
200
1.5
2.0
220
3
2
260
2.5
µA
µA
V
mV
ms
V
EEUVLO
V
EEUVLOH
V
EE_OV
V
OVH
V
EE_UV
V
DD_OV
V
DD_UV
V
DDUVLO
V
DDHYS
Ports shut down and device resets if its junction
temperature exceeds this limit, temperature
increasing
(V
AGND
- V
EE
) < V
EE_UV
, V
AGND
decreasing
(V
DD
- V
DGND
) > V
DD_OV
, V
DD
increasing
(V
DD
- V
DGND
) < V
DD_UV
, V
DD
decreasing
Device operates when (V
DD
- V
DGND
) >
V
DDUVLO
, V
DD
increasing
(V
AGND
- V
EE
) > V
EE_OV
, V
AGND
increasing
V
AGND
- V
EE
, (V
AGND
– V
EE
) increasing
28.5
3
62.5
1
40
3.71
2.82
1.3
120
V
V
V
V
V
V
V
V
mV
SYMBOL
V
TH_FB
V
OUT_
= V
AGND
V
SENSE_
= V
EE
CONDITIONS
MIN
TYP
64
-2
MAX
UNITS
mV
µA
MAX5935
T
SHD
T
SHDH
+150
20
°C
°C
_______________________________________________________________________________________
3
Quad Network Power Controller
for Power-Over-LAN
MAX5935
ELECTRICAL CHARACTERISTICS (continued)
(AGND = +48V. V
EE
= 0V, V
DD
to DGND = +3.3V. All voltages are referenced to V
EE
, unless otherwise noted. Typical
values are at AGND = +48V, DGND = +48V, V
DD
= (DGND + 3.3V), T
A
= +25°C. Currents are positive when entering the pin and
negative otherwise.)
PARAMETER
AC Load Disconnect
Threshold (Note 4)
Oscillator Buffer Gain
OSC_IN Fail Threshold
(Note 5)
OSC_IN Input Resistance
OSC_IN Input Capacitance
Load Disconnect Timer
DETECTION
Detection Probe Voltage
(First Phase)
Detection Probe Voltage
(Second Phase)
Current-Limit Protection
Short-Circuit Threshold
Open-Circuit Threshold
Resistor Detection Window
Resistor Rejection Window
CLASSIFICATION
Classification Probe Voltage
Current-Limit Protection
V
CL
I
ClLIM
V
AGND
- V
DET_
during classification
V
DET_
= V
AGND
, during classification,
measure current through DET_
Class 0, Class 1
Classification Current
Thresholds
I
CL
Classification current
thresholds between
classes
Class 1, Class 2
Class 2, Class 3
Class 3, Class 4
>Class 4
DIGITAL INPUTS/OUTPUTS (REFERRED to DGND)
Digital Input Low
Digital Input High
V
IL
V
IH
2.4
0.9
V
V
16
50
5.5
13.0
21
31
45
6.5
14.5
23
33
48
20
75
7.5
16.0
25
35
51
mA
V
mA
V
DPH1
V
DPH2
I
DLIM
V
DCP
I
D_OPEN
R
DOK
R
DBAD
V
AGND
- V
DET_
during the first detection phase
V
AGND
- V
DET_
during the second detection
phase
V
DET_
= V
AGND
, during detection, measure
current through DET_
If V
AGND
- V
OUT
< V
DCP
after the first detection
phase a short circuit to AGND is detected
First point measurement current threshold for
open condition
(Note 7)
Detection rejects lower values
Detection rejects higher values
32
19.0
3.8
9.0
1.5
4
9.3
1.75
1.62
12.5
26.5
15.2
4.2
9.6
2.0
V
V
mA
V
µA
kΩ
kΩ
SYMBOL
I
ACTH
A
OSC
V
OSC_FAIL
Z
OSC
C
OSC_IN
t
DISC
Time from V
SENSE
< V
DCTH
or current into DET_
< I
ACTH
to gate shutdown (Note 6)
300
CONDITIONS
Current into DET_, ACD_EN_ bit = high,
OSC_IN = 2.2V
V
DET_
/V
OSC_IN
, ACD_EN_ bit = high,
C
DET
= 400nF
Port will not power on if V
OSC_IN
< V
OSC_FAIL
and
ACD_EN_ bit = high
OSC_IN input impedance when all the ACD_EN_
are active
MIN
300
2.90
1.8
100
5
400
TYP
325
2.93
1.9
MAX
350
3.1
2.2
UNITS
µA
V/ V
V
kΩ
pF
ms
4
_______________________________________________________________________________________
Quad Network Power Controller
for Power-Over-LAN
ELECTRICAL CHARACTERISTICS (continued)
(AGND = +48V. V
EE
= 0V, V
DD
to DGND = +3.3V. All voltages are referenced to V
EE
, unless otherwise noted. Typical
values are at AGND = +48V, DGND = +48V, V
DD
= (DGND + 3.3V), T
A
= +25°C. Currents are positive when entering the pin and
negative otherwise.)
PARAMETER
Internal Input Pullup/Pulldown
Resistor
Open-Drain Output Low
Voltage
Open-Drain Leakage
TIMING
Startup Time
t
START
Time during which a current limit set by V
SU_LIM
is allowed, starts when the GATE_ is turned on
(Note 8)
Maximum allowed time for an overcurrent
condition set by V
FLT_LIM
after startup (Note 8)
Minimum delay between any port turning off,
does not apply in the case of a reset
Maximum time allowed before detection
is completed
2.0
Time allowed for classification
Time V
AGND
must be above the V
EEUVLO
thresholds before the device operates
RSTR bits = 00
Time a port has to wait
before turning on after an
overcurrent fault,
RSTR_EN bit = high
RSTR bits = 01
RSTR bits = 10
RSTR bits = 11
Watchdog Clock Period
Serial Clock Frequency
Bus Free Time Between a
STOP and a START Condition
Hold Time for Start Condition
Low Period of the SCL Clock
High Period of the SCL Clock
t
WD
f
SCL
t
BUF
t
HD, STA
t
LOW
t
HIGH
Rate of decrement of the watchdog timer
(Note 9)
(Note 9)
(Note 9)
(Note 9)
(Note 9)
1.2
0.6
1.2
0.6
TIMING CHARACTERISTICS for 2-WIRE FAST MODE
(Figures 5 and 6)
400
kHz
µs
µs
µs
µs
2
16 x
t
FAULT
32 x
t
FAULT
64 x
t
FAULT
0
164
ms
ms
50
60
70
ms
SYMBOL
R
DIN
V
OL
I
OL
CONDITIONS
Pullup (pulldown) resistor to V
DD
(DGND) to set
default level
I
SINK
= 15mA
Open-drain high impedance, V
O
= 3.3V
MIN
25
TYP
50
MAX
75
0.4
2
UNITS
kΩ
V
µA
MAX5935
Fault Time
Port Turn-Off Time
Detection Time
Midspan Mode Detection
Delay
Classification Time
V
EEUVLO
Turn-On Delay
t
FAULT
t
OFF
t
DET
t
DMID
t
CLASS
t
DLY
50
0.5
60
0.75
70
1
320
2.4
40
4
ms
ms
ms
s
ms
ms
Restart Timer
t
RESTART
_______________________________________________________________________________________
5
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