DC1567B - Demo Manual

DEMO MANUAL DC1567B
LTC4274
Single Port IEEE802.3at PSE
Description
Demonstration circuit 1567B features the LTC®4274, a
single power sourcing equipment (PSE) controller designed
for use in IEEE 802.3 Type 1 and Type 2 (high power) compliant Power over Ethernet (PoE) systems. The LTC4274
is configured in the DC1567B as a midspan power injector
where data comes in from an existing network system
and out, along with power, to a powered device (PD). The
LTC4274 autonomously detects and classifies a PD, turns
power on to the port, and disconnects port power without
the need for a microcontroller. A two second backoff timer
supports the midspan configuration.
Only a single 55V supply is required to power the DC1567B.
A simple regulator circuit on the board powers the digital
supply of the LTC4274.
The LTC4274 delivers low heat dissipation by utilizing a
low RON external MOSFET and a 0.25Ω sense resistor,
eliminating the need for expensive heat sinks. An external
MOSFET also provide a more robust solution compared
to an integrated MOSFET.
Power controlled by the LTC4274 is connected to the center
taps on the cable side of the Ethernet transformers for data
pairs 4/5 and 7/8. An integrated RJ45 connector includes
the Ethernet transformer, common mode termination,
and LEDs. One LED is also controlled by the LTC4274
to indicate the port is powered. Test turrets provide test
points for port power measurements.
The DC1567B has increased surge protection from the
DC1567A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1567B
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
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1
DEMO MANUAL DC1567B
Typical Performance
Table 1. Typical DC1567B Performance Summary (TA = 25°C)
PARAMETER
CONDITION
VALUE
Input Voltage
GND – VEE, Typical Voltage, IEEE Type 1 and Type 2 Complaint
Output
51V to 57V
VDD Supply Voltage
VDD – DGND, Generated on Demo Board from VEE
3.4V to 3.8V
Powered Pairs
PoE Power at RJ45 Connector
Alternative-B (Positive on Pins 4/5,
Negative on 7/8)
PSE Operation Mode
AUTO Pin Logic High
IEEE802.3at Mode
Midspan Backoff
MID Pin Logic High, Backoff Time After Detection
2.5s
Detection Type
25k Signature Detection
4-Point PD Detection
Class 4
2-Event Classification
PD Detected and Port Power is On
LED On
Port Power is Off
LED Off
Port Output Voltage
VEE = –55.0V, RSENSE = 0.25Ω, MOSFET = PHT6NQ10T,
Port Load = 600mA, VPORT+ – VPORT–
–54.7V
Disconnect Current
DC Disconnect, Maintain Power Signature, Typical Disconnect
Current at the Port for 350ms, RSENSE = 0.25Ω
<7.8mA
AUTO Pin High Mode
Overcurrent Sense
RSENSE = 0.25Ω, Class 0 or Class 3
376mA
RSENSE = 0.25Ω, Class 1
112mA
RSENSE = 0.25Ω, Class 2
208mA
RSENSE = 0.25Ω, Class 4
636mA
RJ45 Amber LED Indicator
2
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DEMO MANUAL DC1567B
Quick Start Procedure
(Figure 1)
1.Connect a 55V power supply across AGND and VEE as
shown in Figure 1.
2.Connect probes across VPORT+ and VPORT– for
measurements.
3.Connect with a CAT5 cable to a PD at J1.
4.Connect a PHY with a CAT5 cable to J2 for data testing
(optional).
55V
+–
Data in
from PHY
VPORT
V
RJ45
RJ45
Data and Power
Out to PD
DC1567B F01
Figure 1. DC1567B Setup
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3
DEMO MANUAL DC1567B
Operation
DC1567B provides a simple single port IEEE 802.3at
Type 1 and Type 2 PSE solution with the LTC4274. It runs
fully autonomously and only requires a supply at VEE.
Detection, classification, port power on and disconnect is
all performed without the need of a microcontroller. The
voltage drop to the port is minimized with the LTC4274
solution because of the low RON external MOSFET and a
0.25Ω sense resistor, thus reducing power consumption.
Input Supply
IEEE 802.3at requires that a Type 2 PSE output at the
port between 50V to 57V. To meet this requirement, it is
recommended to supply a nominal 55V across AGND and
VEE on the DC1567B as shown in Figure 1. Main PS LED
indicates the input power supply is powering the LTC4274.
VDD Supply
DC1567B generates a VDD supply from VEE using just three
components allowing for VEE to be the only required supply. VDD is tied to AGND and DGND is a negative voltage
below AGND.
AUTO Pin High Mode
The AUTO pin on the LTC4274 is tied logic high on the
DC1567B to set the device to AUTO pin high mode. In
AUTO pin high mode, the LTC4274 autonomously detects,
classifies, powers on a valid detected PD, and disconnects
power to the port when the PD is removed. An LED in the
integrated RJ45 connector displays if the port is powered.
Midspan
The LTC4274 on the DC1567B, the MID pin is tied logic
high to set the device to midspan mode. In midspan mode,
port detection occurs every midspan backoff time of 2.5s.
4
Detection and Classification
The LTC4274 performs 4-point PD detection with 2-point
forced voltage and 2-point forced current for higher reliability of valid PD detection. Once a valid PD is detected,
classification is carried out. The LTC4274 in AUTO pin high
mode detects and classifies class 0 through class 4 PDs
and sets the port current limits according to the PD class.
In the event a class 4 is detected, the LTC4274 outputs a
2-Event classification to signal to the PD that it is a valid
IEEE 802.3at PSE and can supply the high power.
Disconnect
The LTC4274 performs DC disconnect. In order for a PD
to remain on, it must display a maintain power signature
by drawing more than 10mA. If the port load is less than
5mA for 350ms (typ), then the LTC4274 will remove power
from the port.
Overcurrent
The LTC4274 in AUTO pin high mode detects, classifies
and sets the current limits according to the classification
results. Refer to Table 1 for the overcurrent limits with a
0.25Ω sense resistor.
SHDN and RESET Pushbuttons
The DC1567B has pushbuttons to the LTC4274 SHDN,
RESET and DGND pins. Momentarily tying SHDN to DGND
will shut down the port if it is on and disable detection
preventing the port from turning on again. Momentarily
tying RESET to DGND will reset the LTC4274 to its AUTO
pin high mode state without having to cycle power.
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DEMO MANUAL DC1567B
Surge Protection
Ethernet ports can be subject to significant cable surge
events. To keep PoE voltages below a safe level and protect
the application against damage, protection components
are required at the main supply, at the LTC4274 supply
pins and at the port.
The LTC4274 requires a 10Ω, 0805 resistor (R10) in series
from supply AGND to the LTC4274 AGND pin. Across the
LTC4274 AGND pin and VEE pin are an SMAJ58A, 58V
TVS (D3) and a 1μF, 100V bypass capacitor (C4). These
components must be placed close to the LTC4266 pins.
Bulk transient voltage suppression devices and bulk
capacitance are required across the main PoE supply
and should be sized to accommodate system level surge
requirements. The DC1567B diode D2 and capacitor C2
are example components for this protection at the main
PoE supply.
The port requires a pair of S1B clamp diodes: one from
OUT to supply AGND and one from OUT to supply VEE. The
diodes at the ports steer harmful surges into the supply
rails where they are absorbed by the surge suppressors
and the VEE bypass capacitance. The layout of these paths
must be low impedance.
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5
A
B
C
E2
D2
SMBJ58A
VEE
_
55V
+
1
2
E1
5
+
VEE
C2
4.7uF
100V
R5
750k
1
CMHZ4687-4.3V
D1
AGND
2
1
R10
10 0805
1
2
2
3
MAIN PS
INPUTS
R17
10k
R18
10k
Q2
CMPTA92
ORANGE
MAIN PS
D6
R13
1k
1
2
2
R14
0
10
15
16
17
36
4
DGND
DGND
DGND
DGND
MID
AUTO
D3
SMAJ58A
TP1
DGND
C1
0.1uF
R11 0
VDD 13
VDD
R12 0 33
U1
SHDN
SW1
RESET
TP2
R15
0
C4
1uF
100V
R16
0
1
RS2
RS3
1
1
1
RS1
RS4
TP3
SDAOUT
SW2
LTC4274CUHF
1
2
14
18
MSD
34
SHDN
AGND
35
RESET
7
INT
INT
38
SCL
37
19
22
25
26
27
39
VEE
VEE
VEE
VEE
VEE
VEE
3
SDAIN
1
SDAOUT
SENSE
4
2
8
2
9
11
12
20
21
23
24
28
29
J2
1
2
3
4
5
6
7
8
R8
100k
VEE
1
D5
S1B
D4
S1B
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
E3
VPORT-
E4
C3
1000pF
2kV
R3 75
R4 75
R2 75
R1 75
ECO
20
19
17
18
16
15
13
14
9
7
8
2
1
3
5
6
4
10
12
11
1
2
SCALE = NONE
DATE:
N/A
SIZE
DESCRIPTION
REBUILD WITH CHANGE
1
DILIAN R.
SHIELD2
SHIELD1
8
7
5
4
6
3
2
1
22
IC NO.
Thursday, July 09, 2015
1
DEMO CIRCUIT 1567B
SHEET
1
OF
SINGLE PORT IEEE 802.3at PSE
LTC4274CUHF
1
1
REV.
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
J1
0838-1X1T-W7
1000pF 2kV
4 X 12nF
100V
4 X 75 Ohms
TECHNOLOGY
LED2Y
LED2X
LED1C
LED1A
VC2B
VC2A
VC1A
VC1B
TRD4-
TRCT4
TRD4+
TRD3-
TRCT3
TRD3+
TRD2-
TRCT2
TRD2+
TRD1-
TRCT1
TRD1+
21
DATE
07-09-15
APPROVED
REVISION HISTORY
DATA AND POWER TO PD
REV
DILIAN R. TITLE: SCHEMATIC
KIM T.
APPROVALS
VEE
VPORT+
FB2
Q10
CMPTA42
RLED
12k
1/4W
2
FB1
C5
0.22uF
100V
SS-7188S-A-NF
10
9
CUSTOMER NOTICE
Q1
PHT6NQ10T
3
DNC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
DATA
FROM
PHY
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
APP ENG.
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
30
6
AD0
1
AD2
4
AD3
5
AD1
GATE
31
1
OUT
32
3
1
2
1
2
4
3
6
2
D
5
A
B
C
D
DEMO MANUAL DC1567B
Schematic Diagram
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DEMO MANUAL DC1567B
PCB Layout and Film
Top Assembly
Top Side
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7
DEMO MANUAL DC1567B
pcb layout and film
Inner Layer 2
Inner Layer 3
8
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DEMO MANUAL DC1567B
pcb layout and film
Bottom Side
Assembly Bottom
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
9
DEMO MANUAL DC1567B
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
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observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
10 Linear Technology Corporation
dc1567bfa
LT 0915 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2010
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