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
complete power-supply solution as IEEE
®
802.3af-com-
pliant 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 323mA 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 volt-
age range from 8.7V to 60V and supports up to 6.49W
of input power. The MAX5986A/MAX5986B/MAX5987A
operate at a fixed 215kHz switching frequency and
the MAX5986C operates at a fixed 430kHz switching
frequency. The DC-DC converter operates at a fixed
switching 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
operate 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
●
High Integration Saves Space and BOM Cost
•
Efficient, Integrated DC-DC Converter (with
Integrated Switches)
•
Built-In Output-Voltage Monitoring
•
Protects Against Overload, Output Short Circuit,
Output Overvoltage, and Overtemperature
•
Integrated TVS Diode Withstands Cable
Discharge Event (CDE)
•
Internal LDO Regulator with Up to 100mA Load
(MAX5987A)
● IEEE 802.3af-Compliant Features Reduce Design Time
•
PoE Class 1/Class 2 Classification Set with
Single Resistor
•
Intelligent Maintain Power Signature (MPS)
Complies with IEEE 802.3af Specification
•
Simplified Wall Adapter Interface
•
Pass 2kV, 200m CAT-6 Cable Discharge Event
● High Efficiency During Light Loads Reduces Power
Consumption
•
Sleep and Ultra-Low-Power Mode (MAX5986A/
MAX5986B/MAX5986C)
•
Frequency Foldback for High-Efficiency Light-Load
Operation
•
Back-Bias Capability to Optimize the Efficiency
● Robust Performance
•
8.7V to 60V Wide Input Voltage Range
•
Hiccup-Mode Runaway Current Limit
•
49mA (typ) Inrush Current Limit
•
Open-Drain RESET Output (MAX5987A)
● Flexible and Easy to Design With
•
3.0V to 14V Programmable Output Voltage Range
•
Internal Compensation
•
Fixed 215kHz/430kHz Switching Frequency
•
Fixed 3.3V or Adjustable Output Voltage through
an External Resistive Divider
Applications
●
●
●
●
●
IEEE 802.3af-Powered Devices
IP Phones
Wireless Access Nodes
IP Security Cameras
WiMAX
®
Base Stations
19-6261; Rev 6; 11/16
MAX5986A–MAX5986C/
MAX5987A
Absolute Maximum Ratings
IEEE 802.3af-Compliant, High-Efficiency, Class 1
/Class 2, PDs with Integrated DC-DC Converter
(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
VDRV to V
DD
............................................ -0.3V to (V
DD
+ 0.3V)
Note 1:
See Figure 1, Test Circuit.
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
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.
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-lay-
er 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. 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
www.maximintegrated.com
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. 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
V
DD
Deglitch Time
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
I
WAD
V
WAD
= 24V
I
INRUSH
I
LIM
V
WAD_RISE
V
WAD_FALL
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
125
39
290
49
323
60
360
8.8
mA
mA
V
V
V
FA
SYMBOL
V
ON
V
OFF
V
DD
rising
V
DD
falling
MAX5986A/B/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
150
123
1.2
1.5
18
14
28.7
24
4.3
4.8
10
12.6
95
190
40
35
MAX
37.6
40
UNITS
V
V
V
Fs
ms
I
V
HYST_UVLO
(Note 6)
t
OFF_DLY
t
DELAY
R
ON_ISO
V
DD
falling from 40V to 20V (Note 5)
t
DELAY
= time from a (V
DD
- V
CC
) 1.5V
to 0V
I
VCC
= 100mA
T
J
= +25NC
T
J
= +85NC
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
mA
mA
mA
mA
mA
ms
ms
www.maximintegrated.com
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. V
CLASS2
= 0V, V
MPS
= 0V. 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
V
TH
V
WK
falling and V
ULP
rising and falling
Falling
V
SL
= 0V
R
SL
= 121kI, V
LED
= 6.5V
R
SL
= 60.4kI, V
LED
= 6.5V
R
SL
= 30.2kI, V
LED
= 6.5V
R
SL
= 30.2kI, V
LED
= 3.5V
9.2
19.2
1.6
0.55
62.5
5.3
10.6
21.2
21.2
10
V
SL
= 0V
f
ILED
D
ILED
I
VDD
D
IVDD
t
MPS
t
MPDO
T
SD
T
SD,HYS
Sleep and ultra-low
power modes
Sleep and ultra-low
power modes
MAX5986B/C
MAX5986B/C
10
76
205
20.6
26.4
250
25
12
75
87
235
151
16
98
265
14.5
20
31.4
mA
mA
Hz
%
mA
%
ms
ms
NC
NC
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
I
SINK
= 1mA
-10
0.4
0.2
+10
2.9
V
V
V
FA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LED Current Amplitude
I
LED
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
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
T
J
rising
Sleep mode, V
LED
= 6.5V
Sleep and ultra-low power modes
Ultra-low power mode
Ultra-low power mode
www.maximintegrated.com
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. V
CLASS2
= 0V, V
MPS
= 0V. 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 Falling Threshold
DC-DC CONVERTER INPUT SUPPLY
V
DD
Voltage Range
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
10
ms
R
DSON-H
R
DSON-L
I
LX-LKG
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
V
DD,RISING
V
CC
= V
DD
= V
WAD
- 0.3V, rising
8
7.7
60
60
V
DD,FALLING
V
CC
= V
DD
= V
WAD
- 0.3V, falling
V
2.0
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
4.2
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
www.maximintegrated.com
Maxim Integrated │ 5
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