EVALUATION KIT AVAILABLE
MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
General Description
The MAX5986A–MAX5986C/MAX5987A provide a com-
plete power-supply solution as IEEE
®
802.3af-compliant
Class 1/Class 2 Powered Devices (PDs) in a Power-over-
Ethernet (PoE) system. The devices integrate the PD
interface with an efficient DC-DC converter, offering a low
external part count PD solution. The MAX5987A includes
a low-dropout regulator and the MAX5986A–MAX5986C
include sleep and ultra-low power modes.
The PD interface provides a detection signature and
a Class 1/Class 2 classification signature with a single
external resistor. The PD interface also provides an
isolation power MOSFET, a 60mA (max) inrush current
limit, and a 201mA (MAX5986A) or 323mA (MAX5986B/
MAX5986C/MAX5987A) operating current limit.
The integrated step-down DC-DC converter uses a peak
current-mode control scheme and provides an easy-to-
implement architecture with a fast transient response. The
step-down converter operates in a wide input voltage range
from 8.7V to 60V and supports up to 3.84W (MAX5986A)
or 6.49W (MAX5986B/MAX5986C/MAX5987A) of input
power. The MAX5986A operates at a fixed 275kHz
switching frequency, while the MAX5986B/MAX5987A
operate at a fixed 215kHz switching frequency and the
MAX5986C operates at a fixed 430kHz switching fre-
quency. The DC-DC converter operates at a fixed switch-
ing frequency, with an efficiency-boosting frequency
foldback that reduces the switching frequency by half at
light loads.
The devices feature an input undervoltage-lockout
(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 devices also feature overtemperature
shutdown, short-circuit protection, output overvoltage
protection, and hiccup current limit for enhanced perfor-
mance and reliability.
The MAX5986A–MAX5986C/MAX5987A are available in
a 16-pin, 5mm x 5mm, TQFN power package and oper-
ate over the -40°C to +85°C temperature range.
Ordering Information
appears at end of data sheet.
IEEE is a registered service mark of the Institute of Electrical
and Electronics Engineers, Inc.
WiMAX is a registered certification mark and registered service
mark of WiMAX Forum.
Benefits and Features
S
IEEE 802.3af Compliant
S
PoE Class 1/Class 2 Classification
S
Simplified Wall Adapter Interface
S
Intelligent MPS
S
Sleep and Ultra-Low-Power Mode (MAX5986A/
MAX5986B)
S
Efficient, Integrated DC-DC Converter (with
Integrated Switches)
S
8.7V to 60V Wide Input Voltage Range
S
3.0V to 14V Programmable Output Voltage Range
S
Internal Compensation
S
Fixed 214kHz/275kHz /430kHz Switching
Frequency
S
Frequency Foldback for High-Efficiency Light-
Load Operation
S
Built-In Output-Voltage Monitoring
S
Open-Drain RESET Output (MAX5987A)
S
Protects Against Overload, Output Short Circuit,
Output Overvoltage, and Overtemperature
S
Hiccup-Mode Runaway Current Limit
S
Back-Bias Capability to Optimize the Efficiency
S
Integrated TVS Diode Withstands Cable Discharge
Event (CDE)
S
Internal LDO Regulator with Up to 100mA Load
(MAX5987A)
S
Fixed 3.3V or Adjustable Output Voltage Through
an External Resistive Divider
S
49mA (typ) Inrush Current Limit
S
Pass 2kV, 200m CAT-6 Cable Discharge Event
Applications
IEEE 802.3af-Powered Devices
IP Phones
Wireless Access Nodes
IP Security Cameras
WiMAX
®
Base Stations
For related parts and recommended products to use with this part,
refer to
www.maximintegrated.com/MAX5986A/MAX5987A.related.
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-6261; Rev 3; 1/14
MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.)
V
DD
to GND...........................................................-0.3V to +70V
(100V, 100ms, R
TEST
= 3.3kω) (Note 1)
V
CC
, WAD, RREF to GND ........................ -0.3V to (V
DD
+ 0.3V)
AUX, LDO_IN, LED to GND .................................... -0.3V to 16V
LDO_OUT to GND .............................. -0.3V to (LDO_IN + 0.3V)
LDO_FB to GND ......................................................-0.3V to +6V
LX to GND ................................................ -0.3V to (V
CC
+ 0.3V)
LDO_OUT, VDRV, FB,
RESET,
WK,
SL, ULP,
MPS, CLASS2
to GND ..............................................................-0.3V to +6V
Note 1:
See Figure 1, Test Circuit.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
VDRV to V
DD
............................................ -0.3V to (V
DD
+ 0.3V)
PGND to GND ......................................................-0.3V to +0.3V
LX Total RMS Current ...........................................................1.6A
Continuous Power Dissipation (T
A
= + 70NC)
TQFN (derate 28.6mW/NC above +70NC) ..............2285.7mW
Operating Temperature Range .......................... -40NC to +85NC
Junction Temperature .....................................................+150NC
Storage Temperature Range............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
PACKAGE THERMAL CHARACTERISTICS (Note 2)
Junction-to-Ambient Thermal Resistance (q
JA
) ..............35°C/W
Junction-to-Case Thermal Resistance (q
JC
) ..................2.7°C/W
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.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
DD
= 48V, R
SIG
= 24.9kω, LED, V
CC
,
SL, ULP, WK, RESET,
LDO_OUT unconnected, WAD = LDO_EN = LDO_IN = PGND =
GND, C1 = 68nF, C2 = 10µF, C3 = 1µF (see Figure 3), V
FB
= V
AUX
= 0V, LX unconnected. V
CLASS2
= 0V, V
MPS
= 0V (except for
MAX5986A). All voltages are referenced to GND, unless otherwise noted. T
A
= T
J
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.) (Note 3)
PARAMETER
POWER DEVICE (PD) INTERFACE
DETECTION MODE
Input Offset Current
Effective Differential Input
Resistance
CLASSIFICATION MODE
Classification Enable Threshold
Classification Disable Threshold
Classification Stability Time
Classification Current
POWER MODE
V
DD
Supply Voltage Range
V
DD
Supply Current
V
DD
I
DD
V
DD
= 60V
MAX5986A/B/
MAX5987A
MAX5986C
3.6
4.8
60
4.5
6.6
V
mA
I
CLASS
V
DD
= 12.6V
to 20V
CLASS2 = GND
CLASS2 = VDRV
9.12
16.1
V
TH,CLS,EN
V
TH,CLS,DIS
V
DD
rising
V
DD
rising
10.2
22
11.5
23
2
10.5
18
11.88
20.9
12.5
23.8
V
V
ms
mA
I
OFFSET
dR
V
VDD
= 1.4V to 10.1V (Note 4)
V
VDD
= 1.4V to 10.1V with 1V step,
(Note 5)
23.95
10
25.5
FA
kI
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
2
MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 48V, R
SIG
= 24.9kω, LED, V
CC
,
SL, ULP, WK, RESET,
LDO_OUT unconnected, WAD = LDO_EN = LDO_IN = PGND =
GND, C1 = 68nF, C2 = 10µF, C3 = 1µF (see Figure 3), V
FB
= V
AUX
= 0V, LX unconnected. V
CLASS2
= 0V, V
MPS
= 0V (except for
MAX5986A). All voltages are referenced to GND, unless otherwise noted. T
A
= T
J
= -40°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.) (Note 3)
PARAMETER
V
DD
Turn-On Voltage
V
DD
Turn-Off Voltage
V
DD
Turn-On/Off Hysteresis
SYMBOL
V
ON
V
OFF
V
DD
rising
V
DD
falling
MAX5986A/B/C
MAX5987A
MAX5986A
MAX5986B/C/
MAX5987A
CONDITIONS
MAX5986A/B/C
MAX5987A
MIN
34.3
37.2
30
3.4
TYP
35.7
38.7
31.4
4.2
7.2
116
150
90
123
1.2
1.5
18
14
28.7
24
4.3
4.8
10
12.6
95
190
40
35
ms
Fs
MAX
37.6
40
UNITS
V
V
V
V
HYST_UVLO
(Note 6)
V
DD
falling from
40V to 20V
(Note 5)
V
DD
Deglitch Time
t
OFF_DLY
Inrush to Operating Mode Delay
Isolation Power MOSFET
On-Resistance
PoE MPS Current Rising Threshold
PoE MPS Current Falling
Threshold
PoE MPS Current Threshold
Hysteresis
PoE MPS Output Average Current
PoE MPS Peak Output Current
PoE MPS Time High
PoE MPS Time Low
CURRENT LIMIT
Inrush Current Limit
Current Limit During Normal
Operation
WAD Detection Rising Threshold
WAD Detection Falling Threshold
WAD Detection Hysteresis
WAD Input Current
t
DELAY
t
DELAY
= time from MAX5986A
a (V
DD
- V
CC
) 1.5V MAX5986B/C/
to 0V
MAX5987A
I
VCC
= 100mA
T
J
= +25NC
T
J
= +85NC
R
ON_ISO
I
MAINTAIN POWER SIGNATURE (MPS = VDRV)
I
MPS_RISE
I
MPS_FALL
I
MPS_HYS
I
MPS_AVE
I
MPS_PEAK
t
MPS_HIGH
t
MPS_LOW
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
During initial turn-on period,
V
DD
- V
CC
= 4V, measured at V
CC
After inrush completed,
V
CC
= V
DD
– 1.5V,
measured at V
CC
(Note 9)
(Note 9)
5.8
0.6
I
WAD
V
WAD
= 24V
125
MAX5986A
MAX5986B/C/
MAX5987A
mA
mA
mA
mA
mA
ms
ms
I
INRUSH
39
175
290
49
201
323
60
226
360
8.8
mA
I
LIM
V
WAD_RISE
V
WAD_FALL
mA
V
V
V
FA
Maxim Integrated
3
MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 48V, R
SIG
= 24.9kω, LED, V
CC
,
SL, ULP, WK, RESET,
LDO_OUT unconnected, WAD = LDO_EN = LDO_IN = PGND = GND,
C1 = 68nF, C2 = 10µF, C3 = 1µF (see Figure 3), V
FB
= V
AUX
= 0V, LX unconnected. All voltages are referenced to GND, unless
otherwise noted. T
A
= T
J
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
LOGIC
CLASS2, MPS Voltage Rising
Threshold
CLASS2, MPS Voltage Falling
Threshold
RESET
Output Voltage Low
(MAX5987A Only)
CLASS2, MPS Leakage
INTERNAL REGULATOR WITH BACK BIAS
V
AUX
Input Voltage Range
V
AUX
Input Current
V
DRV
Output Voltage
SLEEP MODE (MAX5986A–MAX5986C)
WK
and
ULP
Logic Threshold
SL
Logic Threshold
SL
Current
LED Current Amplitude
I
LED
V
TH
V
WK
falling and V
ULP
rising and falling
Falling
V
SL
= 0V
R
SL
= 60.4kI, V
LED
= 6.5V
R
SL
= 30.2kI, V
LED
= 6.5V
R
SL
= 30.2kI, V
LED
= 3.5V
LED Current Programmable Range
LED Current with Grounded
SL
LED Current Frequency
LED Current Duty Cycle
V
DD
Current Amplitude
Internal Current Duty Cycle
Internal Current Enable Time
Internal Current Disable Time
THERMAL SHUTDOWN
MAX5986A
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
T
SD
T
SD,HYS
T
J
rising
MAX5986B/C
MAX5987A
143
151
16
NC
NC
f
ILED
D
ILED
I
VDD
D
IVDD
t
MPS
t
MPDO
V
SL
= 0V
Sleep and ultra-low power modes
Sleep and ultra-low power modes
Sleep mode, V
LED
= 6.5V
Sleep and ultra-low power modes
Ultra-low power mode
Ultra-low power mode
10
76
205
10
20.6
26.4
250
25
12
75
87
235
98
265
14.5
9.2
19.2
1.6
0.55
62.5
10.6
21.2
21.2
20
31.4
mA
mA
Hz
%
mA
%
ms
ms
12
23.5
mA
2.9
0.8
V
V
FA
V
AUX
Inferred from V
AUX
input current
V
AUX
from 4.75V to 14V
4.75
0.65
4.2
14
3.1
5.5
V
mA
V
MAX5986B/MAX5986C/MAX5987A only
MAX5986B/MAX5986C/MAX5987A only
I
SINK
= 1mA
MAX5986B/MAX5986C/MAX5987A only
-10
0.4
0.2
+10
2.9
V
V
V
FA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
4
MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 48V, R
SIG
= 24.9kω, LED, V
CC
,
SL, ULP, WK, RESET,
LDO_OUT unconnected, WAD = LDO_EN = LDO_IN = PGND = GND,
C1 = 68nF, C2 = 10µF, C3 = 1µF (see Figure 3), V
FB
= V
AUX
= 0V, LX unconnected. All voltages are referenced to GND, unless
otherwise noted. T
A
= T
J
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
LDO (MAX5987A)
Input Voltage Range
Output Voltage
Max Output Voltage Setting
LDO FB Regulation Voltage
LDO FB Leakage Current
Dropout
Load Regulation
Line Regulation
Overcurrent Protection Threshold
LDO_FB Rising Threshold
LDO_FB Hysteresis
DC-DC CONVERTER INPUT SUPPLY
V
DD,RISING
V
DD
Voltage Range
V
CC
= V
DD
=
V
WAD
- 0.3V,
rising
MAX5986A
MAX5986B/C/
MAX5987A
MAX5986A
MAX5986B/C/
MAX5987A
8.7
8
7.3
7.7
60
60
60
60
V
2.3
I
OVC
V
LDO_IN
= 5V, V
LDO_FB
= V
DRV
,
I
LOAD
= 80mA
I
LOAD
from 1mA to 80mA
VLDO_IN from 4.5V to 14V
85
3.2
2.4
3.7
Inferred from line regulation
LDO_FB = V
DRV
With external divider to LDO_FB
1.2
4.5
3.3
5.5
1.227
±1
300
0.5
1.4
1.25
14
V
V
V
V
FA
mV
mV/mA
mV/V
mA
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
= V
DD
=
V
DD,FALLING
V
WAD
- 0.3V,
falling
R
DSON-H
R
DSON-L
I
LX-LKG
POWER MOSFETs
High-Side pMOS On-Resistance
Low-Side nMOS On-Resistance
LX Leakage Current
SOFT-START (SS)
Soft-Start Time
FEEDBACK (FB)
FB Regulation Voltage
FB Input Bias Current
OUTPUT VOLTAGE
Output Voltage Range
V
OUT
MAX5986A/MAX5987A
MAX5986B/MAX5986C
3.0
5.4
5.6
14
V
V
FB-RG
I
FB
V
FB
= 1.224V
1.203
1.225
10
1.252
200
V
nA
t
SS-TH
MAX5986A
MAX5986B/MAX5986C/MAX5987A
7.45
10
ms
I
LX
= 0.5A (sourcing)
I
LX
= 0.5A (sinking)
V
DD
= V
CC
= 28V,
V
LX
= (V
PGND
+ 1V) to (V
CC
- 1V)
-5
0.54
0.16
+5
I
I
FA
Maxim Integrated
5
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