_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
_______________________________________________________________ Maxim Integrated Products 1
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
General Description
The MAX5969A/MAX5969B provide a complete interface
for a powered device (PD) to comply with the IEEE®
802.3af/at standard in a power-over-Ethernet (PoE) sys-
tem. The MAX5969A/MAX5969B provide the PD with a
detection signature, classification signature, and an inte-
grated isolation power switch with inrush current control.
During the inrush period, the MAX5969A/MAX5969B limit
the current to less than 180mA before switching to the
higher current limit (720mA to 880mA) when the isolation
power MOSFET is fully enhanced. The devices feature
an input UVLO with wide hysteresis and long deglitch
time to compensate for twisted-pair cable resistive drop
and to assure glitch-free transition during power-on/-off
conditions. The MAX5969A/MAX5969B can withstand up
to 100V at the input.
The MAX5969A/MAX5969B support a 2-event classifica-
tion method as specified in the IEEE 802.3at standard
and provide a signal to indicate when probed by Type 2
power-sourcing equipment (PSE). The devices detect
the presence of a wall adapter power-source connec-
tion and allow a smooth switchover from the PoE power
source to the wall power adapter.
The MAX5969A/MAX5969B also provide a power-good
(PG) signal, two-step current limit and foldback, over-
temperature protection, and di/dt limit.
The MAX5969A/MAX5969B are available in a space-sav-
ing, 10-pin, 3mm x 3mm, TDFN power package. These
devices are rated over the -40NC to +85NC extended
temperature range.
Applications
IEEE 802.3af/at Powered Devices
IP Phones, Wireless Access Nodes, IP Security
Cameras
WiMAXK Base Station
Features
S IEEE 802.3af/at Compliant
S 2-Event Classification
S Simplified Wall Adapter Interface
S PoE Classification 0 to 5
S 100V Input Absolute Maximum Rating
S Inrush Current Limit of 180mA Maximum
S Current Limit During Normal Operation Between
720mA and 880mA
S Current Limit and Foldback
S Legacy UVLO at 36V (MAX5969A)
S IEEE 802.3af/at-Compliant, 40V UVLO (MAX5969B)
S Overtemperature Protection
S Thermally Enhanced, 3mm x 3mm, 10-Pin TDFN
19-5008; Rev 0; 12/09
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Ordering Information
Pin Configuration
IEEE is a registered service mark of the Institute of Electrical
and Electronics Engineers, Inc.
WiMAX is a trademark of WiMAX Forum.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-
PACKAGE
UVLO
THRESHOLD
(V)
MAX5969AETB+ -40NC to +85NC10 TDFN-EP* 35.4
MAX5969BETB+ -40NC to +85NC10 TDFN-EP* 38.6
1
3
4
10
8
7
CLS
PG
WAD
VDD
N.C.
I.C.
EP*
*EP = EXPOSED PAD. CONNECT TO VSS.
MAX5969A
MAX5969B
2 9 2ECDET
5 6 RTNVSS
TDFN
(3mm × 3mm)
TOP VIEW
+
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
2 ______________________________________________________________________________________
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.
VDD to VSS ..........................................................-0.3V to +100V
DET, RTN, WAD, PG, 2EC to VSS .......................-0.3V to +100V
CLS to VSS ..............................................................-0.3V to +6V
Maximum Current on CLS (100ms maximum) .................100mA
Continuous Power Dissipation (TA = +70NC) (Note 1)
10-Pin TDFN (derate 24.4mW/NC above +70NC)
Multilayer Board ........................................................1951mW
Package Thermal Resistance (Note 2)
BJA .................................................................................4NC/W
BJC ................................................................................9NC/W
Operating Temperature Range .......................... -40NC to +85NC
Maximum Junction Temperature .....................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Soldering Temperature (reflow) .................................... +260NC
ELECTRICAL CHARACTERISTICS
(VIN = (VDD - VSS) = 48V, RDET = 24.9kω, RCLS = 619ω. RTN, WAD, PG, and 2EC unconnected, all voltages are referenced to VSS,
unless otherwise noted. TA = TJ = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3)
ABSOLUTE MAXIMUM RATINGS
Note 1: Maximum power dissipation is obtained using JEDEC JESD51-5 and JESD51-7 specifications.
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DETECTION MODE
Input Offset Current IOFFSET VIN = 1.4V to 10.1V (Note 4) 10 FA
Effective Differential Input
Resistance dR VIN = 1.4V up to 10.1V with 1V step,
VDD = RTN = WAD = PG = 2EC (Note 5) 23.95 25.00 25.5 kI
CLASSIFICATION MODE
Classification Disable
Threshold VTH,CLS VIN rising (Note 6) 22.0 22.8 23.6 V
Classification Stability Time 0.2 ms
Classification Current ICLASS
VIN = 12.5V to
20.5V, VDD =
RTN = WAD =
PG = 2EC
Class 0, RCLS = 619I0 3.96
mA
Class 1, RCLS = 117I9.12 11.88
Class 2, RCLS = 66.5I17.2 19.8
Class 3, RCLS = 43.7I26.3 29.7
Class 4, RCLS = 30.9I36.4 43.6
Class 5, RCLS = 21.3I52.7 63.3
TYPE 2 (802.3at) CLASSIFICATION MODE
Mark Event Threshold VTHM VIN falling 10.1 10.7 11.6 V
Hysteresis on Mark Event
Threshold 0.84 V
Mark Event Current IMARK VIN falling to enter mark event, 5.2V P VIN
P 10.1V 0.25 0.85 mA
Reset Event Threshold VTHR VIN falling 2.8 4 5.2 V
POWER MODE
VIN Supply Voltage Range 60 V
VIN Supply Current IQMeasured at VDD 0.27 0.55 mA
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VIN = (VDD - VSS) = 48V, RDET = 24.9kω, RCLS = 619ω. RTN, WAD, PG, and 2EC unconnected, all voltages are referenced to VSS,
unless otherwise noted. TA = TJ = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
VIN Turn-On Voltage VON VIN rising MAX5969A 34.3 35.4 36.6 V
MAX5969B 37.2 38.6 40
VIN Turn-Off Voltage VOFF VIN falling 30 V
VIN Turn-On/-Off Hysteresis
(Note 7) VHYST_UVLO MAX5969A 4.2 V
MAX5969B 7.3
VIN Deglitch Time tOFF_DLY VIN falling from 40V to 20V (Note 8) 30 120 Fs
Inrush to Operating Mode
Delay tDELAY tDELAY = minimum PG current pulse width
after entering into power mode 80 96 112 ms
Isolation Power MOSFET
On-Resistance RON_ISO IRTN = 600mA
TJ = +25NC0.5 0.7
ITJ = +85NC0.65 1
TJ = +125NC0.8
RTN Leakage Current IRTN_LKG VRTN = 12.5V to 30V 10 FA
CURRENT LIMIT
Inrush Current Limit IINRUSH During initial turn-on period,
VRTN = 1.5V 90 135 180 mA
Current Limit During Normal
Operation ILIM After inrush completed,
VRTN = 1V 720 800 880 mA
Foldback Threshold VRTN (Note 9) 13 16.5 V
LOGIC
WAD Detection Threshold VWAD-REF VWAD rising, VIN = 14V to 48V (referenced
to RTN) 8 9 10
V
WAD Detection Threshold
Hysteresis
VWAD falling, VRTN = 0V, VSS
unconnected 0.725
WAD Input Current IWAD-LKG VWAD = 10V (referenced to RTN) 3.5 FA
2EC Sink Current V2EC = 3.5V (referenced to RTN), VSS
unconnected 1 1.5 2.25 mA
2EC Off-Leakage Current V2EC = 48V 1FA
PG Sink Current VRTN = 1.5V, VPG = 0.8V, during inrush
period 125 230 375 FA
PG Off-Leakage Current VPG = 48V 1 FA
THERMAL SHUTDOWN
Thermal-Shutdown Threshold TSD TJ rising +140 NC
Thermal-Shutdown Hysteresis TJ falling 28 NC
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
4 ______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VIN = (VDD - VSS) = 48V, RDET = 24.9kω, RCLS = 619ω. RTN, WAD, PG, and 2EC unconnected, all voltages are referenced to VSS,
unless otherwise noted. TA = TJ = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3)
Note 3: All devices are 100% production tested at TA = +25NC. Limits over temperature are guaranteed by design.
Note 4: The input offset current is illustrated in Figure 1.
Note 5: Effective differential input resistance is defined as the differential resistance between VDD and VSS. See Figure 1.
Note 6: Classification current is turned off whenever the device is in power mode.
Note 7: UVLO hysteresis is guaranteed by design, not production tested.
Note 8: A 20V glitch on input voltage that takes VDD below VON shorter than or equal to tOFF_DLY does not cause the MAX5969A/
MAX5969B to exit power-on mode.
Note 9: In power mode, current-limit foldback is used to reduce the power dissipation in the isolation MOSFET during an overload
condition across VDD and RTN.
Figure 1. Effective Differential Input Resistance/Offset Current
IIN
IINi + 1
IINi
IOFFSET
dRi
1VVINi VINi + 1
IOFFSET = IINi - VINi
dRi
dRi = (VINi + 1 - VINi) = 1V
(IINi + 1 - IINi) (IINi + 1 - IINi)
VIN
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
_______________________________________________________________________________________ 5
Typical Operating Characteristics
(VIN = (VDD - VSS) = 54V, RDET = 24.9kω, RCLS = 615ω. RTN, WAD, PG, and 2EC unconnected; all voltages are referenced to VSS.)
INPUT CURRENT (DETECTION)
vs. INPUT VOLTAGE
MAX5969A toc01
VIN (V)
IIN (mA)
8642
0.1
0.2
0.3
0.4
0.5
0
0 10
IIN = IVDD + IDET
RDET = 24.9kI
RTN = 2EC = PG = WAD = VDD
-40°C P TA P +85NC
SIGNATURE RESISTANCE
vs. INPUT VOLTAGE
RSIGNATURE (kI)
8642
24.5
25.0
25.5
26.0
24.0
0 10
MAX5969A toc02
VIN (V)
IIN = IVDD + IDET
RDET = 24.9kI
RTN = 2EC = PG = WAD = VDD
TA = -40NC
TA = +85NC
TA = +25NC
INPUT OFFSET CURRENT
vs. INPUT VOLTAGE
INPUT OFFSET CURRENT (µA)
8642
-2
0
2
4
-4
0 10
MAX5969A toc03
VIN (V)
TA = +85NC
TA = -40NC
TA = +25NC
INPUT CURRENT (CLASSIFICATION)
vs. INPUT VOLTAGE
MAX5969A toc04
V
IN
(V)
IIN (mA)
252015105
10
20
30
40
50
60
70
0
0 30
CLASS 5
CLASS 4
CLASS 3
CLASS 2
CLASS 1
CLASS 0
CLASSIFICATION SETTLING TIME
MAX5969A toc05
VIN
10V/div
IIN
200mA/div
0V
0A
VCLS
1V/div
100µs/div
RCLS = 30.9I
2EC SINK CURRENT vs. 2EC VOLTAGE
V2EC (V)
I2EC (mA)
5040302010
0.4
0.8
1.2
1.6
2.0
0
0 60
MAX5969A toc06
VSS UNCONNECTED
V2EC REFERENCED TO RTN
VWAD = 14V
TA = -40NC
TA = +85NC
TA = +25NC
PG SINK CURRENT vs. PG VOLTAGE
VPG (V)
IPG (µA)
5040302010
100
150
200
250
300
50
0 60
MAX5969A toc07
TA = -40NC
TA = +85NC
TA = +25NC
INRUSH CURRENT LIMIT
vs. RTN VOLTAGE
MAX5969A toc08
VRTN (V)
INRUSH CURRENT LIMIT (mA)
5040302010
70
90
110
130
150
50
0 60
NORMAL OPERATION CURRENT LIMIT
vs. RTN VOLTAGE
MAX5969A toc09
VRTN (V)
CURRENT LIMIT (mA)
504010 20 30
200
300
400
500
600
700
800
900
100
0 60
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
6 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN = (VDD - VSS) = 54V, RDET = 24.9kω, RCLS = 615ω. RTN, WAD, PG, and 2EC unconnected; all voltages are referenced to VSS.)
INRUSH CONTROL WAVEFORM WITH
TYPE 2 CLASSIFICATION
MAX5969A toc10
0V
0V
0A
0V
VRTN
50V/div
IRTN
100mA/div
VDD
50V/div
V2EC
50V/div
200µs/div
USING TYPICAL APPLICATION CIRCUIT
2EC PULLED UP TO VDD WITH 10kI
ENTERING POWER MODE WITH
TYPE 2 CLASSIFICATION
MAX5969A toc11
VPG
10V/div0V
0V
0V
0A
0V
VRTN
50V/div
IRTN
200mA/div
VDD
50V/div
20ms/div
V2EC
40V/div
USING TYPICAL APPLICATION CIRCUIT
2EC PULLED UP TO VDD WITH 10kI
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
_______________________________________________________________________________________ 7
Pin Description
PIN NAME FUNCTION
1 VDD Positive Supply Input. Connect a 68nF (min) bypass capacitor between VDD and VSS.
2 DET Detection Resistor Input. Connect a signature resistor (RDET = 24.9kI) from DET to VDD.
3 N.C. No Connection. Not internally connected.
4 I.C. Internally Connected. Leave unconnected.
5 VSS Negative Supply Input. VSS connects to the source of the integrated isolation n-channel power
MOSFET.
6 RTN
Drain of Isolation MOSFET. RTN connects to the drain of the integrated isolation n-channel power
MOSFET. Connect RTN to the downstream DC-DC converter ground as shown in the Typical
Application Circuit.
7 WAD
Wall Power Adapter Detector Input. Wall adapter detection is enabled the moment VDD - VSS crosses
the mark event threshold. Detection occurs when the voltage from WAD to RTN is greater than 9V.
When a wall power adapter is present, the isolation n-channel power MOSFET turns off, 2EC current
sink turns on. Connect WAD directly to RTN when the wall power adapter or other auxiliary power
source is not used.
8 PG
Open-Drain Power-Good Indicator Output. PG sinks 230FA to disable the downstream DC-DC converter
while turning on the hot-swap MOSFET switch until the hot-swap switch is fully on. PG current sink is
disabled during detection, classification, and in the steady-state power mode.
92EC
Active-Low 2-Event Classification Detect or Wall Adapter Detect Output. A 1.5mA current sink is
enabled at 2EC when a Type 2 PSE or a wall adapter is detected. When powered by a Type 2 PSE, the
2EC current sink is enabled and latched low after the isolation MOSFET is fully on until VIN drops below
the UVLO threshold. 2EC also asserts when a wall adapter supply, typically greater than 9V, is applied
between WAD and RTN. 2EC is not latched if asserted by WAD.
10 CLS
Classification Resistor Input. Connect a resistor (RCLS) from CLS to VSS to set the desired classification
current. See the classification current specifications in the Electrical Characteristics table to find the resis-
tor value for a particular PD classification.
–– EP
Exposed Pad. Do not use EP as an electrical connection to VSS. EP is internally connected to VSS
through a resistive path and must be connected to VSS externally. To optimize power dissipation, solder
the exposed pad to a large copper power plane.
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
8 ______________________________________________________________________________________
Simplified Block Diagram
1.5mA
46µA
VDD
EN CLS
1.23V
PSE 2
2EC
VDD
5V
11.6V/10.8V
11.6V/4V
D Q
Q
SET
CLR
DET
VSS
5V REGULATOR
5V
1.23V
22.8V/22V
THERMAL
SHUTDOWN
Q
R
S
VDD
VDD
VDD
WAD
WAPD
RTN
VON/VOFF
VDD
D Q
Q
SET
CLR
9V
230µA
PG
CLASSIFICATION
ISWITCH
K x ISWITCH
ISOLATION
SWITCH
S
MUX
I0 135mA
VON/VOFF = 38.6V/31V FOR MAX5969B
VON/VOFF = 35.4V/31V FOR MAX5969A
760mA
I1
1/K
MAX5969A
MAX5969B
95ms
HSON
4V
15V
IREF
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
_______________________________________________________________________________________ 9
Typical Operating Circuit
2-EVENT
CLASSIFICATION
DETECTION
-54V
MAX5969A
MAX5969B
VDD
RTN
WAD
PG
2EC
24V/48V
BATTERY
68nF
RJ-45
AND
BRIDGE
RECTIFIER
GND
SMAJ58A
RDET
24.9kI
RCLS
VSS
DET
CLS
ENABLE
DC-DC
CONVERTER
IN+
IN-
GND
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
10 _____________________________________________________________________________________
Detailed Description
Operating Modes
Depending on the input voltage (VIN = VDD - VSS), the
MAX5969A/MAX5969B operate in four different modes:
PD detection, PD classification, mark event, and PD
power. The devices enter PD detection mode when the
input voltage is between 1.4V and 10.1V. The device
enters PD classification mode when the input voltage is
between 12.6V and 20V. The device enters PD power
mode once the input voltage exceeds VON.
Detection Mode (1.4V ≤ VIN ≤ 10.1V)
In detection mode, the PSE applies two voltages on VIN
in the range of 1.4V to 10.1V (1V step minimum) and
then records the current measurements at the two points.
The PSE then computes DV/DI to ensure the presence
of the 24.9kω signature resistor. Connect the signature
resistor (RDET) from VDD to DET for proper signature
detection. The MAX5969A/MAX5969B pull DET low in
detection mode. DET goes high impedance when the
input voltage exceeds 12.5V. In detection mode, most of
the MAX5969A/MAX5969B internal circuitry is off and the
offset current is less than 10µA.
If the voltage applied to the PD is reversed, install pro-
tection diodes at the input terminal to prevent internal
damage to the MAX5969A/MAX5969B (see the Typical
Application Circuit). Since the PSE uses a slope tech-
nique (DV/DI) to calculate the signature resistance, the
DC offset due to the protection diodes is subtracted and
does not affect the detection process.
Classification Mode (12.6V ≤ VIN ≤ 20V)
In the classification mode, the PSE classifies the PD
based on the power consumption required by the PD. This
allows the PSE to efficiently manage power distribution.
Class 0 to 5 is defined as shown in Table 1. (The IEEE
802.3af/at standard defines only Class 0 to 4 and Class 5
for any special requirement.) An external resistor (RCLS)
connected from CLS to VSS sets the classification current.
The PSE determines the class of a PD by applying a volt-
age at the PD input and measuring the current sourced
out of the PSE. When the PSE applies a voltage between
12.6V and 20V, the MAX5969A/MAX5969B exhibit a cur-
rent characteristic with a value shown in Table 1. The
PSE uses the classification current information to classify
the power requirement of the PD. The classification cur-
rent includes the current drawn by RCLS and the supply
current of the MAX5969A/MAX5969B so the total current
drawn by the PD is within the IEEE 802.3af/at standard
figures. The classification current is turned off whenever
the device is in power mode.
2-Event Classification and Detection
During 2-event classification, a Type 2 PSE probes PD
for classification twice. In the first classification event,
the PSE presents an input voltage between 12.6V and
20V and the MAX5969A/MAX5969B present the pro-
grammed load ICLASS. The PSE then drops the probing
voltage below the mark event threshold of 10.1V and
the MAX5969A/MAX5969B present the mark current
(IMARK). This sequence is repeated one more time.
Table 1. Setting Classification Current
*VIN is measured across the MAX5969A/MAX5969B input VDD to VSS.
CLASS
MAXIMUM
POWER USED
BY PD
(W)
RCLS
(I)
VIN*
(V)
CLASS CURRENT SEEN AT
VIN (mA)
IEEE 802.3af/at PSE
CLASSIFICATION CURRENT
SPECIFICATION (mA)
MIN MAX MIN MAX
0 0.44 to 12.95 619 12.6 to 20 0 4 0 5
1 0.44 to 3.94 117 12.6 to 20 9 12 8 13
2 3.84 to 6.49 66.5 12.6 to 20 17 20 16 21
3 6.49 to 12.95 43.7 12.6 to 20 26 30 25 31
4 12.95 to 25.5 30.9 12.6 to 20 36 44 35 45
5 > 25.5 21.3 12.6 to 20 52 64 — —
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
______________________________________________________________________________________ 11
When the MAX5969A/MAX5969B are powered by a Type 2
PSE, the 2-event identification output 2EC asserts low
after the internal isolation n-channel MOSFET is fully
turned on. 2EC current sink is turned off when VDD goes
below the UVLO threshold (VOFF) and turns on when
VDD goes above the UVLO threshold (VON), unless VDD
goes below VTHR to reset the latched output of the Type 2
PSE detection flag.
Alternatively, the 2EC output also serves as a wall adapt-
er detection output when the MAX5969A/MAX5969B are
powered by an external wall power adapter. See the Wall
Power Adapter Detection and Operation section for more
information.
Power Mode (Wake Mode)
The MAX5969A/MAX5969B enter power mode when VIN
rises above the undervoltage lockout threshold (VON).
When VIN rises above VON, the MAX5969A/MAX5969B
turn on the internal n-channel isolation MOSFET to con-
nect VSS to RTN with inrush current limit internally set
to 135mA (typ). The isolation MOSFET is fully turned on
when the voltage at RTN is near VSS and the inrush cur-
rent is reduced below the inrush limit. Once the isolation
MOSFET is fully turned on, the MAX5969A/MAX5969B
change the current limit to 800mA. The open-drain
power-good output (PG) remains low for a minimum of
tDELAY until the power MOSFET fully turns on to keep the
downstream DC-DC converter disabled during inrush.
Undervoltage Lockout
The MAX5969A/MAX5969B operate up to a 60V sup-
ply voltage with a turn-on UVLO threshold (VON) at
35.4V/38.6V and a turn-off UVLO threshold (VOFF) at 31V.
When the input voltage is above VON, the MAX5969A/
MAX5969B enter power mode and the internal MOSFET
is turned on. When the input voltage goes below VOFF for
more than tOFF_DLY, the MOSFET turns off.
Power-Good Output
An open-drain output (PG) is used to allow disabling
downstream DC-DC converter until the n-channel isola-
tion MOSFET is fully turned on. PG is pulled low to VSS
for a period of tDELAY and until the internal isolation
MOSFET is fully turned on. The PG is also pulled low
when coming out of thermal shutdown.
Thermal-Shutdown Protection
The MAX5969A/MAX5969B include thermal protection
from excessive heating. If the junction temperature
exceeds the thermal-shutdown threshold of +140NC,
the MAX5969A/MAX5969B turn off the internal power
MOSFET and 2EC current sink. When the junction tem-
perature falls below +112NC, the devices enter inrush
mode and then return to power mode. Inrush mode
ensures the downstream DC-DC converter is turned off
as the internal power MOSFET is turned on.
Wall Power Adapter Detection
and Operation
For applications where an auxiliary power source such
as a wall power adapter is used to power the PD,
the MAX5969A/MAX5969B feature wall power adapter
detection. Once the input voltage (VDD - VSS) exceeds
the mark event threshold, the MAX5969A/MAX5969B
enable wall adapter detection. The wall power adapt-
er is connected from WAD to RTN. The MAX5969A/
MAX5969B detect the wall power adapter when the
voltage from WAD to RTN is greater than 9V. When a
wall power adapter is detected, the internal n-channel
isolation MOSFET turns off, 2EC current sink turns on,
and classification current is disabled if VIN is in the clas-
sification range.
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
12 _____________________________________________________________________________________
Applications Information
Operation with 12V Adapter
Layout Procedure
Careful PCB layout is critical to achieve high efficiency
and low EMI. Follow these layout guidelines for optimum
performance:
1) Place the input capacitor, classification resistor, and
transient voltage suppressor as close as possible to
the MAX5969A/MAX5969B.
2) Use large SMT component pads for power dissipat-
ing devices such as the MAX5969A/MAX5969B and
the external diodes.
3) Use short and wide traces for high-power paths.
4) Use the MAX5969 Evaluation Kit layout as a refer-
ence.
Figure 2. Typical Configuration When Using a 12V Wall Power Adapter
68nF
2-EVENT
CLASSIFICATION
(ASSERTED ON)
ENABLE
DC-DC
CONVERTER
IN+
IN-
RJ-45
AND
BRIDGE
RECTIFIER
GND
GND
-54V
SMAJ58A
MAX5969A
MAX5969B
RDET
24.9kI
RCLS
VDD
VSS RTN
WAD
PG
DET
CLS
2EC
12V
BATTERY
THIS CIRCUIT ACHIEVES
PROPER 2EC LOGIC WHEN
BATTERY IS < 12.5V
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
______________________________________________________________________________________ 13
Typical Application Circuit
68nF
ISOLATED 2-EVENT
CLASSIFICATION
OUTPUT
GND
VAC
VAC
GND
-54V
SMAJ58A
MAX5969A
MAX5969B
24.9kI
43.7I
VDD
VSS RTN
WAD
PG
PG
DET
CLS
2EC
24/48V
BATTERY
RTN
MAX15000
UVLO/EN IN
VCC
UFLG
FB
COMP
CS
PG
CS
VCC
VCC
CS
RTN
ISOLATED +5.3V/2A
ISOLATED RTN
ISOLATED RTN
GND
RTN
GND 33kI
10kI
249I
22.1I
0.75I
1kI
619I8.2nF
330pF
649I
4.99kI1kI100pF
33nF
8.06kI
2.49kI
1kI18.1kI
RTN
4.99kI
NDRV
GND
RT
51.5kI
1.37MI0.1µF
0.1µF 0.1µF
0.1µF
22µF
4.7µF
2.2nF
8.06kI
IEEE 802.3af/at-Compliant, Powered Device Interface
Controllers with Integrated Power MOSFET
MAX5969A/MAX5969B
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Package Information
For the latest package outline information and land pat-
terns, go to www.maxim-ic.com/packages. Note that
a “+”, “#”, or “-” in the package code indicates RoHS
status only. Package drawings may show a different suf-
fix character, but the drawing pertains to the package
regardless of RoHS status.
Chip Information
PROCESS: BiCMOS
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
10 TDFN-EP T1033+1 21-0137
