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Электронный компонент: MAX5953AUTM+

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General Description
The MAX5953A/MAX5953B/MAX5953C/MAX5953D
integrate a complete power IC solution for Powered
Devices (PD) in a Power-Over-Ethernet (PoE) system, in
compliance with the IEEE 802.3af standard. The
MAX5953A/MAX5953B/MAX5953C/MAX5953D provide
the PD with a detection signature, a classification sig-
nature, and an integrated isolation switch with program-
mable inrush current control. These devices also
integrate a voltage-mode PWM controller with two
power MOSFETs connected in a two-switch voltage-
clamped DC-DC converter configuration.
An integrated MOSFET provides PD isolation during
detection and classification. All devices guarantee a
leakage current offset of less than 10A during the
detection phase. A programmable current limit pre-
vents high inrush current during power-on. The devices
feature power-mode undervoltage lockout (UVLO) with
wide hysteresis and long deglitch time to compensate
for twisted-pair-cable resistive drop and to assure
glitch-free transition between detection, classification,
and power-on/-off phases. The MAX5953A/MAX5953C
have an adjustable UVLO threshold with the default
value compliant to the 802.3af standard, while the
MAX5953B/MAX5953D have a lower and fixed UVLO
threshold compatible with some legacy pre-802.3af
power-sourcing equipment (PSE) devices.
The DC-DC converters are operable in either forward or
flyback configurations with a wide input voltage range
from 11V to 76V and up to 15W of output power. The
voltage-clamped power topology enables full recovery
of stored magnetizing and leakage inductive energy for
enhanced efficiency and reliability. When using the
high-side MOSFET, the controller can be configured as
a buck converter. A look-ahead signal for driving sec-
ondary-side synchronous rectifiers can be used to
increase efficiency. A wide array of protection features
include UVLO, over-temperature shutdown, and short-
circuit protection with hiccup current limit for enhanced
performance and reliability. Operation up to 500kHz
allows for smaller external magnetics and capacitors.
The MAX5953A/MAX5953B/MAX5953C/MAX5953D are
available in a high-power (2.22W), 7mm x 7mm ther-
mally enhanced thin QFN package.
Features
Powered Device Interface
Fully Integrated IEEE 802.3af-Compliant PD
Interface
PD Detection and Programmable Classification
Signatures
Less than 10A Leakage Current Offset During
Detection
Integrated MOSFET for Isolation and Inrush
Current Limiting
Gate Output Allows External Control of the
Internal Isolation MOSFET
Programmable Inrush Current Control
Programmable Undervoltage Lockout
(MAX5953A/MAX5953C)
DC-DC Converter
Clamped, Two-Switch Power IC for High
Efficiency
Integrated High-Voltage 0.4
Power MOSFETs
Up to 15W Output Power
Bias Voltage Regulator with Automatic High-
Voltage Supply Turn-Off
11V to 76V Wide Input Voltage Range
Feed-Forward Voltage-Mode Control for Fast
Input Transient Rejection
Programmable Undervoltage Lockout
Overtemperature Shutdown
Indefinite Short-Circuit Protection with
Programmable Fault Integration
Integrated Look-Ahead Signal for Secondary-
Side Synchronous Rectification
> 90% Efficiency with Synchronous
Rectification
Up to 500kHz Switching Frequency
High-Power (2.22W), 7mm x 7mm Thermally
Enhanced Lead-Free Thin QFN Package
MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
________________________________________________________________ Maxim Integrated Products
1
PART
PIN-PACKAGE
PKG CODE
MAX5953AUTM+*
48 TQFN
T4877-6
MAX5953BUTM+
48 TQFN
T4877-6
MAX5953CUTM+*
48 TQFN
T4877-6
MAX5953DUTM+*
48 TQFN
T4877-6
Ordering Information
19-3945; Rev 0; 1/06
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.
Operating junction temperature range is 0C to +125C.
+Denotes lead-free package.
*Future product--contact factory for availability.
Pin Configuration and Typical Operating Circuit appear at
end of data sheet.
IEEE 802.3af Powered
Devices
IP Phones
Wireless Access Nodes
Internet Appliances
Security Cameras
Computer Telephony
Applications
MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= (V+ - V
EE
) = 48V, GATE = PGOOD = PGOOD = unconnected, GND = OUT, HVIN = V+, UVLO = V
EE
, T
J
= 0C to +125C, unless
otherwise noted. Typical values are at T
J
= +25C. All voltages are referenced to V
EE
, unless otherwise noted.) (Note 1)
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.
V+ to V
EE
................................................................-0.3V to +90V
OUT, PGOOD, PGOOD to V
EE
.....................-0.3V to (V+ + 0.3V)
RCLASS, GATE to V
EE
...........................................-0.3V to +12V
UVLO to V
EE
............................................................ -0.3V to +8V
PGOOD to OUT ........................................... -0.3V to (V+ + 0.3V)
HVIN, INBIAS, DRNH, XFRMRH,
XFRMRL to GND.................................................-0.3V to +80V
BST to GND ........................................................... -0.3V to +95V
BST to XFRMRH .................................................... -0.3V to +12V
PGND to GND .......................................................-0.3V to +0.3V
DCUVLO, RAMP, CSS, OPTO, FLTINT, RCFF,
RTCT to GND..................................................... -0.3V to +12V
SRC, CS to GND...................................................... -0.3V to +6V
REGOUT, DRVIN to GND .......................................-0.3V to +12V
REGOUT to HVIN .................................................. -80V to +0.3V
REGOUT to INBIAS ............................................... -80V to +0.3V
PPWM to GND....................................-0.3V to (V
REGOUT
+ 0.3V)
Maximum Input/Output Current (Continuous)
OUT to V
EE
....................................................................500mA
V+, RCLASS to V
EE
.........................................................70mA
UVLO, PGOOD, PGOOD to V
EE
.....................................20mA
GATE to V
EE
....................................................................80mA
REGOUT to GND ............................................................50mA
DRNH, XFRMRH, XFRMRL, SRC to GND (Average),
T
J
= +125C..................................................................0.9A
PPWM to GND ..............................................................20mA
Continuous Power Dissipation* (T
A
= +70C)
48-Pin TQFN 7mm X 7mm
(derate 27.8mW/C above +70C) .............................2222mW
JA
................................................................................36C/W
Operating Ambient Temperature Range ................0C to +85C
Operating Junction Temperature Range ..............0C to +125C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-60C to +150C
Lead Temperature (soldering, 10s) .................................+300C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWERED DEVICE (PD) INTERFACE
DETECTION MODE
Input Offset Current
I
OFFSET
V
IN
= 1.4V to 10.1V (Note 2)
10
A
Effective Differential Input
Resistance (Note 3)
dR
V
IN
= 1.4V, up to 10.1V with 1V step
550
k
CLASSIFICATION MODE
Classification Current Turn-Off
Threshold
V
TH,CLASS
V
IN
rising (Note 4)
20.8
21.8
22.5
V
Class 0, R
RCLASS
= 10k
0
2
Class 1, R
RCLASS
= 732
9.17
11.83
Class 2, R
RCLASS
= 392
17.29
19.71
Class 3, R
RCLASS
= 255
26.45
29.55
Classification Current
I
CLASS
V
IN
= 12.6V
to 20V,
R
DISC
=
25.5k
(Notes 5, 6)
Class 4, R
RCLASS
= 178
36.6
41.4
mA
POWER MODE
Operating Supply Voltage
V
IN
V
IN
= (V+ - V
EE
)
67
V
Operating Supply Current
I
IN
Measure at V+, not including R
DISC
,
GATE = V
EE
, HVIN = GND = OUT
0.4
1
mA
MAX5953A/MAX5953C
37.4
38.6
40.2
Default Power Turn-On Voltage
V
UVLO, ON
V
IN
increasing
MAX5953B/MAX5953D
34.3
35.4
36.9
V
Default Power Turn-Off Voltage
V
UVLO,OFF
V
IN
decreasing, MAX5953A/MAX5953C
30
V
*As per JEDEC 51 standard.
MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= (V+ - V
EE
) = 48V, GATE = PGOOD = PGOOD = unconnected, GND = OUT, HVIN = V+, UVLO = V
EE
, T
J
= 0C to +125C, unless
otherwise noted. Typical values are at T
J
= +25C. All voltages are referenced to V
EE
, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX5953A/MAX5953C
7.1
Default Power Turn-On/Off
Hysteresis Voltage
V
HYST,UVLO
MAX5953B/MAX5953D
4
V
External UVLO Programming
Range
V
IN,EX
MAX5953A/MAX5953C only (Note 7)
12
67
V
UVLO External Reference
Voltage
V
REF,UVLO
V
UVLO
increasing
2.400
2.460
2.522
V
UVLO External Reference
Voltage Hysteresis
V
HYST,UVLO
Ratio to V
REF, UVLO
19.2
20
20.9
%
UVLO Bias Current
I
IN,UVLO
V
UVLO
= 2.460V
-1.5
+1.5
A
UVLO Input Ground-Sense
Threshold
V
TH,G,UVLO
(Note 8)
50
440
mV
UVLO Input Ground-Sense Glitch
Rejection
7
s
Power Turn-Off Voltage,
Undervoltage Lockout Deglitch
Time
t
OFF_DLY
V
IN
, V
UVLO
falling (Note 9)
0.32
ms
Isolation Switch n-Channel
MOSFET On-Resistance
R
ON,ISO
Output current = 300mA, V
GATE
= 5.6V,
measured between OUT and V
EE
0.6
1.5
Isolation Switch n-Channel
MOSFET Off-Threshold Voltage
V
GSTH
V
GATE
- V
EE
, OUT = V+,
output current < 1A
0.5
V
GATE Pulldown Switch
Resistance
R
G
Power-off mode, V
IN
= +12V
38
80
GATE Charging Current
I
GATE
V
GATE
= 2V
4.5
10
16.5
A
GATE High Voltage
V
GATE
I
GATE
= 1A
5.59
5.76
5.93
V
V
OUT
- V
EE
decreasing, V
GATE
= 5.75V
1.16
1.23
1.31
V
PGOOD Assertion V
OUT
Threshold (Note 10)
V
OUTEN
Hysteresis
70
mV
V
GATE
- V
EE
increasing
4.62
4.76
4.91
V
PGOOD, PGOOD Assertion
V
GATE
Threshold
V
GSEN
Hysteresis
80
mV
PGOOD, PGOOD Output Low
Voltage
V
OL,PGOOD
I
SINK
= 2mA, V
OUT
(V+ - 5V) (Note 11)
0.2
V
PGOOD Leakage Current
GATE = high, V+ - V
OUT
= 67V (Note 11)
1
A
PGOOD Leakage Current
GATE = V
EE
, PGOOD - V
EE
= 67V
(Note 11)
1
A
MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (DC-DC Controller)
(All voltages referenced to GND, unless otherwise noted. V
HVIN
= +48V, C
INBIAS
= 1F, C
REGOUT
= 2.2F, R
RTCT
= 25k
, C
RTCT
=
100pF, C
BST
= 0.22F, V
CSS
= V
CS
= 0V, V
RAMP
= V
DCUVLO
= 3V, T
J
= 0C to +125C, unless otherwise noted. Typical values are at
T
J
= +25C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Supply Range
V
HVIN
11
76
V
OSCILLATOR (RTCT)
PWM Frequency
f
S
250
kHz
Maximum PWM Duty Cycle
D
MAX
47
%
Maximum RTCT Frequency
f
RTCTMAX
(Note 12)
1
MHz
RTCT Peak Trip Level
V
TH,RTCT
0.51 x V
REGOUT
V
RTCT Valley Trip Level
V
TL,RTCT
1
V
RTCT Input Bias Current
I
IN,RTCT
1
A
RTCT Discharge MOSFET
R
DS(ON)
R
DIS,RTCT
Sinking 50mA
35
85
RTCT Discharge Pulse Width
50
ns
LOOK-AHEAD LOGIC (PPWM)
PPWM to Output Propagation
Delay
t
PPWM
V
PPWM
rising to V
XFRMRL
falling
110
ns
PPWM Output High
V
OH,PPWM
Sourcing 2mA
7.0
11.0
V
PPWM Output Low
V
OL,PPWM
Sinking 2mA
0.2
V
PWM COMPARATOR (OPTO, RAMP, RCFF)
Common-Mode Input Range
V
CM_PWM
0
5.5
V
Input Offset Voltage
10
mV
Input Bias Current
-2
+2
A
RAMP to XFRMRL Propagation
Delay
t
COMPARATOR
From V
RAMP
(50mV overdrive) rising to
V
XFRMRL
rising
100
ns
Minimum OPTO Voltage
V
CSS
= 0V, OPTO sinking 2mA
1.47
V
Minimum RCFF Voltage
RCFF sinking 2mA
2.18
V
REGOUT LDO (REGOUT)
INBIAS unconnected,
V
HVIN
= 11V to 76V
8.3
8.75
9.2
REGOUT Voltage Set Point
V
REGOUT
V
INBIAS
= V
HVIN
= 11V to 76V
9.5
10.6
11.0
V
INBIAS unconnected, V
HVIN
= 15V,
I
REGOUT
= 0 to 30mA
0.25
REGOUT Load Regulation
V
INBIAS
= V
HVIN
= 15V,
I
REGOUT
= 0 to 30mA
0.25
V
INBIAS unconnected, I
REGOUT
= 30mA
1.25
REGOUT Dropout Voltage
V
INBIAS
= V
HVIN
, I
REGOUT
= 30mA
1.25
V
REGOUT Undervoltage
Lockout Threshold
REGOUT rising
6.6
7.0
7.4
V
REGOUT Undervoltage
Lockout Threshold Hysteresis
REGOUT falling
0.7
V
MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
_______________________________________________________________________________________
5
ELECTRICAL CHARACTERISTICS (DC-DC Controller) (continued)
(All voltages referenced to GND, unless otherwise noted. V
HVIN
= +48V, C
INBIAS
= 1F, C
REGOUT
= 2.2F, R
RTCT
= 25k
, C
RTCT
=
100pF, C
BST
= 0.22F, V
CSS
= V
CS
= 0V, V
RAMP
= V
DCUVLO
= 3V, T
J
= 0C to +125C, unless otherwise noted. Typical values are at
T
J
= +25C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SOFT-START (CSS)
Soft-Start Current
I
CSS
V
CSS
= 0V
33
A
INTEGRATING FAULT PROTECTION
FLTINT Source Current
I
FLTINT
80
A
FLTINT Trip Point
V
FLTINT
rising
2.7
V
FLTINT Hysteresis
0.75
V
INTERNAL POWER FETs
On-Resistance
R
ON,POWER
V
DRVIN
= V
BST
= 9V,
V
XFRMRH
= V
SRC
= 0V, I
DS
= 50mA
0.4
0.8
Off-State Leakage Current
-5
+10
A
Total Gate Charge Per Power
FET
15
nC
HIGH-SIDE DRIVER
Low to High Latency
t
LH-HS
Driver delay until FET V
GS
reaches 0.9 x
(V
BST
- V
XFRMRH
) and is fully on
80
ns
High to Low Latency
t
HL-HS
Driver delay until FET V
GS
reaches 0.1 x
(V
BST
- V
XFRMRH
) and is fully off
40
ns
Output Drive Voltage
V
BST
BST to XFRMRH with high side on
8
V
LOW-SIDE DRIVER
Low to High Latency
t
LH-LS
Driver delay until FET V
GS
reaches 0.9 x
V
DRVIN
and is fully on
80
ns
High to Low Latency
t
HL-LS
Driver delay until FET V
GS
reaches 0.1 x
V
DRVIN
and is fully off
40
ns
CURRENT-LIMIT COMPARATOR (CS)
Current-Limit Threshold
Voltage
V
ILIM
140
156
172
mV
Current-Limit Input Bias
Current
I
BILIM
0 < V
CS
< 0.3V
-2
+2
A
Propagation Delay to XFRMRL
t
dILIM
From V
CS
rising (10mV overdrive) to
V
XFRMRL
rising
160
ns
BOOST VOLTAGE CIRCUIT (See Figure 9, QB)
Driver Output Delay
t
PPWMD
200
ns
One-Shot Pulse Width
t
PWQB
300
ns
QB R
DSON
Sinking 20mA
30
60
THERMAL SHUTDOWN
Shutdown Temperature
T
SH
Temperature rising
+160
C
Thermal Hysteresis
T
H
20
C