AN-37: LX1752 UC3844 Triple Isolated PoE PD Power Supply

POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Triple Isolated Power Supply for POE Powered Device
Application Using UC3844 and LX1752
Evaluation Board
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
CONTENTS
INTRODUCTION………………………………………………………………………………………..3
KEY FEATURES………………………………………………………………………………………..3
APPLICATIONS………………………………………………………………………………………...3
ORDERING INFORMATION……………………………………………………………………………..3
OPERATION……………………………………………………………………………………………4
PERFORMANCE………………………………………………………...………………………………5-7
EVALUATION BOARD SCHEMATIC…………………………………………………………………….8-10
BILL OF MATERIALS…………………………………………………………………………………..11-13
PCB LAYOUT………………………………………………………………………………………….14-18
TEST SETUP & PROCEDURE…….……………………………………………………………………...19-20
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Introduction to Product
The multi-output power supply evaluation board is a fully assembled and tested printed circuit board (PCB) that
provides three step-down regulated output voltages with a 36V to 57V input at 13W. The power supply is designed
for Power Over Ethernet (POE) applications, specifically the Powered Device (PD) or the receiver end. Figure 1
shows a block diagram of the PD power supply. The power supply consists of the following sections: Input filter
and rectifier, PD interface, EMI filter, 5V output isolated flyback converter, and 5V to 3.3V and 1.8V non-isolated
step down converters. The UC3844 is designed as the isolated flyback converter and the LX1752 generates the
step down dual outputs. The flyback converter is configured using 13W. The power capability of the design can be
increased to 30W by changing the flyback transformer and output rectifier diode to a higher power rating.
Note that the power supply circuitry (minus the PD interface) is not limited to POE applications and can be used in
any application requiring a 36V to 57V input and step down output(s) adjusted for the required voltage(s).
Figure 1 – Block Diagram
36V to 57V
POE Input
Input Filter
and
Rectifier
PD
Interface
EMI
Filter
Isolated
Flyback
5VDC
5V to 3.3V
Step-Down
3.3VDC
5V to 1.8V
Step-Down
1.8VDC
Key Features:
● 36V to 57V Input Range
● Output Voltages
5V (Isolated Flyback Output)
3.3V (Step-down Switching Regulator)
1.8V (Step-down Switching Regulator)
● 13Watt Input
● Adjustable Output Voltages using External Resistors
● 70% Overall Efficiency
● Power Device Interface
Applications:
● Power Over Ethernet Powered Device / Receiver End Supply
● Multi-output Power Supply
Ordering Information:
● Part # LX1752-POE-PD13W
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Evaluation Board Operation:
The evaluation board accepts a 36V to 57V input via a CAT-5 cable connected to the Ethernet connector port (J1).
The connector J1 integrates an RF transformer for Ethernet data coupling and also an input filter that conducts RF
interferences to chassis ground. Connector J2 routes and outputs the Ethernet data from port J1. The diode
bridges (U1 and U2), which allow the positive and negative terminals of the input supply to be interchanged, are
rated at 1.5A.
The Powered Device (PD) interface consists of a detection, classification, and isolation circuits. The detection
block supports two different detection schemes, which comprises of a 25kΩ resistor detection, as required by the
IEEE 802.3a standard, and also an input capacitor detection. Classification is optionally performed by the Power
Sourcing Equipment (PSE) to determine the level of power consumption by the PD. Isolation circuitry blocks power
from the PSE to the flyback during detection and classification. For a detailed explanation of the Power Device
interface, refer to Application Note AN-125.
The isolated flyback converter uses the UC3844 current mode controller set to operate at 200kHz. The converter
runs in a discontinuous mode. The isolated feedback is provided using an opto-isolator driven by an error amplifier
made from a TL431. Additional compensation is provided using the error amplifier contained within the UC3844.
The power transformer T1 has a primary side inductance of 27uH +/-15%. Note that upon initial power up, the
flyback controller (U3) is kick-started by the energy stored in C13, which is charged up by the input voltage source.
After startup, the auxiliary winding will generate the bootstrap voltage to keep U3 enabled. The power transformer
also includes a reset winding via an ultra-fast rectifier diode (D8) to ground, to clamp leakage inductance
overshoots when M2 turns off and also to provide a path that returns the leakage energy to the input for improving
efficiency.
To further prevent premature startup of the flyback converter, the circuitry consisting of Q6, Q7, and Q8 is a
comparator used to hold off the UC3844 by providing a low impedance path from the COMP output through Q8 to
ground until M1 is completely turned on. When M1 is turned off, the base voltage of Q6 will be less than the base
voltage of Q7, driving the gate of Q8 high. When M1 is turned on and the input voltage rises to its nominal value,
the base voltage of Q6 will be higher than the base voltage of Q7, pulling the gate of Q8 low to turn it off, allowing
the COMP pin to rise to start the flyback circuit.
A soft-start is implemented by adding D11, C18, and R30 to the COMP pin of the UC3844 since the COMP pin
voltage directly controls the maximum current through the switch. Finally, note that since the flyback converter has
a pulsed input current, an EMI filter is included to prevent the 200kHz current chop from becoming conducted
emissions. The EMI filter consists of L4, C6, and C7.
The final stage of the POE PD power supply consists of the LX1752 buck regulator configured to operate at a
switching frequency of 800kHz, with output voltages set at 1.8V and 3.3V. The buck inputs, the input supply VIN to
the LX1752, and VCCL of the LX1752 are powered by the 5V output of the flyback and are all tied to the same
node. Feedback compensation of the LX1752 is provided externally using type 2. The current limit for both outputs
is set at approximately 5A and can be externally adjusted. For more information regarding the LX1752, please
refer to the device datasheet.
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Performance:
Performance of the POE PD Power Supply is observed for 13W at the input under the following conditions:
Nominal Output
Voltage
1.8V
3.3V
5V
Output Current
1A
1A
0.75A
Overall Efficiency at Full Load Conditions
The overall efficiency is the total output power of the 3 regulated outputs with respect to the input power applied at
the Ethernet port connector.
VIN=36V
70.5%
Overall Efficiency (includes the diode bridges, PD
interface, filters, Flyback, and Buck)
5V @ 0.75A
VIN=48V
70%
1.8V @ 1A
3.3V @ 1A
VIN=57V
69.7%
LX1752 Buck Efficiency
1.8V @ 1A
3.3V @ 1A
VIN=5V
92.6%
Output Ripple
Output Voltage
5V Flyback Output, VIN = 48V
No Load
10mVpp
Full Load
16mVpp
1.8V Step-Down Output, VIN = 48V
15mVpp
17mVpp
3.3V Step-Down Output, VIN=48V
20mVpp
22mVpp
Line Regulation
5V @0.75A, VIN=36V, 57V
<0.1%
1.8V @1A, VIN=36V, 57V
<0.1%
3.3V @1A, VIN=36V, 57V
<0.1%
Load Regulation
5V @ no load and 0.75A, VIN=48V
<0.1%
1.8V @ no load and 1A, VIN=48V
<0.1%
3.3V @ no load and 1A, VIN=48V
<0.1%
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
TYPICAL CHARACTERISTICS @ 25°C (REFER TO FIGURE 2)
Hot Insertion Startup Under Full Load Conditions
Hot Insertion Startup Under Full Load Conditions
PowerDsine 3001 limits
inrush currents
CH1 – POE Input Source
CH1 – POE Input Source
CH4 – POE Input Current
CH2 – 5V Flyback Output at 750mA
CH2 – Flyback Input Voltage
CH3 – 3.3V Buck Output at 1A
CH3 – 5V Flyback Output Loaded at 750mA
CH4 – 1.8V Buck Output at 1A
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
TYPICAL CHARACTERISTICS @ 25°C (REFER TO FIGURE 2)
3.3V Buck Output Step Load Response
1.8V Buck Output Step Load Response
Output AC
Coupled
Output AC
Coupled
Post Filtered 5V Flyback Output Step Load Response
5V Flyback Switching Waveforms
Output AC
Coupled
Note: Output ringing during step load due to LC filter (L1,
C11, C12) resonance. LC filter attenuates flyback output ripple
voltage.
CH1 – Current into M2 External NFET
CH2 – Current into Rectifier D9
CH3 – Extermal NFET Drain Voltage
CH4 – Transformer Secondary Output Voltage
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Schematic
J1
Isolation Block
U1
4
-
3
+
48V
2
DF005M
R3
24.9k
1
0813-1X1T-57F
R2
10k
R1
475k
D4
BZX84C24
R6
511
U2
J2
4
-
3
+
D5
1
2
3
4
5
6
7
8
S1
S2
DF005M
1SMA58A
C2
47nF
100V
R11
475k
C3
100pF
D3
BZX84C11
R7
511
Q2
MMBTA06
D7
BZX84C5V1
R4
475k
R8
511
R5
51.1k
R9
20k
R13
49.9k
Q3
KST92
C1
0.1uF
100V
R10
422k
R14
475k
Q4
MMBTA06
Q5
2N7002
557484-1
D2
BZX84C30
D1
BZX84C12
Q1
KST92
R12
475k
2
TX+
TXRX+
NU
NU
RXNU
NU
SHLD
SHLD
Detection Block
1
1
2
3
4
5
6
7
8
9
10
11
12
S1
S2
RD+
TD+
NU
NU
VC1+
VC2+
CT
RDTDVC1VC2NU
SHLD
SHLD
D6
BZX84C10
C4
0.1uf
M1
48VRTN
STD16NF06
Classification Block is stuffed on the evaluation
board and optionally performed by the PSE.
RAWGND
Note: For different levels of classification, R2 must
be adjusted to the proper value. See AN-125 for details.
J3
+5V
+3.3V
+1.8V
1
2
3
4
5
6
7
8
9
10
11
12
[email protected] MAX
[email protected] MAX
GND
GND
[email protected] MAX
[email protected] MAX
GND
GND
[email protected] MAX
[email protected] MAX
GND
GND
CON12
Figure 2 – Ethernet Connectors, Diode Bridges, PD Interface Schematic
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Schematic
C5
NU
L4
48V
1
2
R17
118k
2N3906
C6
+
R18
1M
48VRTN
180uF/63V
C7
0.1uF
100V
C8
330pF
2N3906
+
820uF/6.3V
3
Q6
Q7
Q8
2N7002
R22
221k
R23
1M
+5V
C11
10uF
6.3V
+
C10
C12
10uF
6.3V
820uF/6.3V
6
D10
5
2
9
7
8
1
10
CDBA-140
C13
CMR1U-02M
D8
47uF/35V
1M
+5VA
+
HA3905-CL Coilcraf t
R26
U3
8
4
R28
3.01k
2
1
C17 R30
1000pF 1M
2
4
R24
R25
16.2k
T1
L1
1uH
C9
R20
75
R19
11.5k
R21
1
MBRS320
RAWGND
255k
NU
D9
100uH
R16
1.0M
C15
0.01uF
R15
D11
VCC
RT/CT
VFB
COMP
FQD10N20
R27
2.7
VREF
OUT
ISNS
GND
C14
M2
7
6
1000p
2500V
1.0k
C16
100pF
3
R29
0.43
5
UC3844
C18
4.7uF
PMBD914
R31
R32
R34
NU
C21
NU
2
118k
1k
ISO1
SFH6156-2
R36
U4
TL431AIDR
1
1uF
3
R33
4
750
C19
R35
1.0k
C20
NU
10k
C22
R37
1.0k
R38
1.0k
NU
Figure 3 – 48V to 5V Isolated Flyback Schematic
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 9
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Schematic
R39
40.2K
R40
C23
NU
NU
C24
R41
0.1uF
R42
13.3k
21.0K
+5VA
+5VA
R43
1K
C26
R44
1K
NU
C29
NU
C36
1uF
23
EO1
24
EA1-
26
25
SSEN1
PSET
RFREQ
LO1
CS2
PGND
21
20
R47
1
+1.8V
2.00K
C30
C33
19
6
0.1uF
Q9B
FDS6911
17
C31
10uF
6.3V
820uF
6.3V
5
4
18
+
3
16
15
+5VA
CR1
NU
9
R51
27
VIN
14
R49
R50
5.62K
8
13
NU
7
HR1
12
C37
1.2nF +5VA
HO1
EO2
VS2
160K
VC1
LX1752
EA2-
11
C35
R48
6
SSEN2
10
C34
VS1
U5
7
L2 3.3uH
Q9A
FDS6911
22
LO2
5
SHDN2
VCCL
4
SHDN1
HR2
0.22uF
NU
C28
10uF
2
CS1
HO2
3
C32
+ C27
8
SY NC
VC2
2
VREF
28
VIA
GND
1.0uF
R46
1K
R45
160K
1.2nF
1
+5VA
C25
+5VA
CMDSH-3
C38
1.0uF
21.0K
C39
C40
4.7uF
1.0uF
6.3V
CR2
CMDSH-3
+5VA
C41
1.0uF
C43
+ C42
R52
2.00K
6
5
NU
10uF
4
C44
0.1uF
L3 3.3uH
Q10B
FDS6911
3
+3.3V
8
7
2
Q10A
FDS6911
C46
820uF
6.3V
+
C45
10uF
6.3V
1
Figure 3 – 5V to 1.8V and 3.3V Dual Output Step-Down Converter Schematic
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 10
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Evaluation Board Build Of Materials
Qty
Reference Designators
13W POE PD Evaluation Board BOM
Part Number
Value
Vendor
Package Type
2
C1, 7
GCM21BR72A104
0.1uF, 100V
Murata
805
1
C2
GRM21BR72A473
47nF, 100V
Murata
805
2
C3,16
ECJ-1VC1H101K
100pF, 50V
Panasonic
603
4
C4, 24, 33, 44
ECJ-1VB1E104K
0.1uF, 25V
Panasonic
603
1
C6
UHE1J181MPD
180uF, 63V
Nichicon
10x20
1
C8
ECJ-2VB2D331K
330pF, 200V
Panasonic
805
4
C9, 10, 30, 46
6.3MCZ820M8X11.5
820uF, 6.3V
Rubycon
8.0 x 11.5
6
C11, 12, 28, 31, 43, 45
JMK212BJ106M
10uF, 6.3V
Taiyo Yuden
1
C13
ECA-1VHG470
47uF, 35V
Panasonic
1
C14
62O102MQECS
1000pF, 2500V
AVX
1
C15
ECJ-1VB1C103
0.01uF, 16V
Panasonic
603
1
C17
ECJ-1VB1H102
1000pF, 50V
Panasonic
603
2
C18, 40
JMK212BJ475M
4.7uF, 6.3V
Taiyo Yuden
805
8
JMK212BJ105M
1uF, 16V
Taiyo Yuden
805
3
C19, 25, 36, 38, 39, 41, 43,
45
C5, 27, 42
Not Used
Through hole
7
C20, 21, 22, 23, 26, 34, 37
Not Used
603
2
C29, 35
ECJ-1VB1H122
1200pF, 50V
Panasonic
603
1
C32
ECJ-1VB1E224K
0.22uF, 25V
Panasonic
603
2
CR1, 2
CMDSH-3
30V, 100mA
Central Semi
1
D1
BZX84C12
Zener, 12V, 5%
Philips
SOT-23
1
D2
BZX84C30
Zener, 30V, 5%
Philips
SOT-23
1
D3
BZX84C11
Zener, 11V, 5%
Philips
SOT-23
1
D4
BZX84C24
Zener, 24V, 5%
Philips
SOT-23
1
D5
1SMA58A
58V, 400W, TVS
On Semi
1
D6
BZX84C10
Zener, 10V, 5%
Philips
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
805
5.0 x 11
Through hole
SOD-323
SMA
SOT-23
Page 11
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
1
D7
BZX84C5V1
Zener, 5.1V, 5%
Philips
1
D8
CMR1U-02M
200V, 1A
Central Semi
SMA
1
D9
MBRS320
20V, 3A
On Semi
SMC
1
D10
CDBA140-G
40V, 1A
Comchip
SMA
1
D11
PMBD914
75V, 215mA
Philips
SOT-23
1
ISO1
SFH6156-2
Opto, CTR 100%
Vishay
SMD-4
1
J1
0813-1X1T-57F
RJ-45 POE
Bel
Non std
1
J2
557484-1
RJ-45
Tyco
Non std
1
J3
p/o PBC36SFCN
12 p x 0.1”ctr
Sullins
16 pin header
1
L1
2643000801
1uH
Fair-rite
Ferrite bead
2
L2, 3
SPC-10049P-3R3
3.3uH 6A
TMP
10x10
1
L4
SMI-0805-0101
100uH, 1.2A
TMP
13.3 x 9.4
1
M1
STD16NF06L
Nch, 60V, 24A
ST Micro
DPAK
1
M2
FQD10N20
Nch, 200V, 7.8A
Fairchild
DPAK
2
Q1, 3
KST92
PNP,300V, 0.5A
Fairchild
SOT-23
2
Q2, 4
MMBTA06
On Semi
SC-70
2
Q6, Q7
SMBT3906
NPN,80V,
300mA
Dual PNP, 40V
Infineon
SOT-363
2
Q5, 8
2N7002
Philips
SOT-23
2
Q9, 10
FDS6911
Fairchild
SOIC8
5
R1, 4, 11, 12, 14
ERJ-6ENF4753V
Nch, 60V,
385mA
Dual Nch 20V
7.5A
475k, 1/8W
Panasonic
805
1
R2
ERJ-6ENF1002V
10.0k, 1/8W
Panasonic
805
1
R3
ERJ-6ENF2492V
24.9k, 1/8W
Panasonic
805
1
R5
ERJ-3EKF2492V
51.1, 1/10W
Panasonic
603
3
R6, 7, 8
ERJ-6ENF5110V
511, 1/8W
Panasonic
805
1
R9
ERJ-6ENF2002V
20k, 1/8W
Panasonic
805
1
R10
ERJ-6EKF4223V
422k, 1/10W
Panasonic
603
1
R13
ERJ-3EKF4992V
49.9k, 1/10W
Panasonic
603
5
R16, 18, 23, 24, 30
ERJ-3EKF105V
1.0M, 1/10W
Panasonic
603
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
SOT-23
Page 12
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
2
R17, R33
ERJ-3EKF1183V
118k, 1/10W
Panasonic
603
1
R25
ERJ-6ENF1622V
16.2k, 1/8W
Panasonic
805
1
R19
ERJ-6ENF1152V
11.5k, 1/8W
Panasonic
805
1
R20
RMC1/875R01%G
75 1/4W
SEI
1206
1
R21
ERJ-3EKF2553V
255k, 1/10W
Panasonic
603
1
R22
ERJ-3EKF2213V
221k, 1/10W
Panasonic
603
1
R26
ERJ-3GEYJ2R7V
2.7, 1/10W
Panasonic
603
8
ERJ-3EKF1001V
1.00k, 1/10W
Panasonic
603
1
R27, 32, 35, 37, 38, 43, 44,
46
R28
ERJ-3EKF3011V
3.01k, 1/10W
Panasonic
603
1
R29
73L6R47J
0.47, 3/4W
CTS
2010
1
R31
ERJ-3EKF7500V
750, 1/10W
Panasonic
603
1
R36
ERJ-3EKF1002V
10k, 1/10W
Panasonic
603
1
R39
ERJ-3EKF4022V
40.2k, 1/10W
Panasonic
603
3
R34, 40, 49
Not Used
603
1
R15
Not Used
1206
1
R41
ERJ-3EKF1332V
13.3k, 1/10W
Panasonic
603
2
R42, 51
ERJ-3EKF2102V
21.0k, 1/10W
Panasonic
603
2
R45, 48
ERJ-3EKF1603V
160k, 1/10W
Panasonic
603
2
R47, 52
ERJ-3EKF2001V
2.0k, 1/10W
Panasonic
603
1
R50
ERJ-3EKF5621V
5.62k, 1/10W
Panasonic
603
1
T1
HA3905-CL
Flyback Tfmr
Coilcraft
2
U1,2
DF005S
Bridge Rect
Fairchild
1
U3
UC3844ADM
CMPS Controller
Microsemi
SOIC8
1
U4
TL431AIDR
Shunt Regulator
TI
SOIC8
1
U5
LX1752CLQ
Dual PWM
Microsemi
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
SDIP
MLPQ28
Page 13
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Evaluation Board PCB Layout
Top Silkscreen and Solder Mask
Top Layer
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 14
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Top Layer
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 15
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Inner Layer 2
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 16
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Inner Layer 3
Bottom Layer
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 17
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Bottom Layer
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 18
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Test Setup:
Test Procedure:
The following is a demonstration scenario that can be used to evaluate the POE PD power supply:
1) The evaluation board can be powered over Ethernet via 48V, or by a regular external power supply for
testing without network connectivity.
2) To verify the circuit operation over the full input range, use a bench top DC power supply capable of
generating a voltage range of 36V to 57V and a current output of 1A for sourcing power via either node
VC1+/VC1- or VC2+/VC2-. Set the power supply current limit to 500mA. Insure that the supply is shut off
before connecting.
3) For power over Ethernet interface, use a POE source such as the PowerDsine 3001 Midspan from
Microsemi and connect the Data & Power Out Port to the evaluation board port J1 via a CAT-5 cable. The
evaluation board should now be powered by 48V.
4) If using an external power supply, set the supply voltage to 57V. Turn on the power supply. Without any
output load currents, verify that the input current from the supply is below 30mA.
5) Using an oscilloscope, monitor the 5V output of the flyback at connector J3. Also monitor the step-down
outputs of 1.8V and 3.3V at connector J3.
6) Using DMM (Digital Multi Meter), verify the nominal output DC voltages are stable at connector J3:
+5VDC nominal +/-3%, +1.8VDC nominal +/-3%, +3.3VDC nominal +/-3%
7) Test load regulation. Using resistive load or electronic load, apply a 1A load at each of the 1.8V and 3.3V
output, and a 750mA load at the 5V output. Monitor with DVM that the output voltages remain within 3%
of the nominal. Note that the input current from the external power supply will be approximately 228mA at
57V or 270mA at 48V.
8) Test line regulation at full load conditions: Reduce the power supply voltage from 57V to 36V and verify
that the output voltages remain within +/-3% of the nominal output voltages. Line regulation test is only
applicable using external power supply to adjust the input voltage.
9) With power over Ethernet, connect another CAT-5 cable from port J2 to a computer for network
connectivity. Actual setup using PowerDsine 3001 Midspan is shown below and can be used to verify
actual network connectivity.
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 19
POE PD POWER SUPPLY
EVALUATION BOARD USER GUIDE
Power Over Ethernet Using PowerDsine 3001 Midspan for Network Connectivity
POE PD Evaluation
Board
Port J2 Provides
Data Interface to
Computer
CAT-5 Ethernet
Connection (grey
cable), Data In,
No Power
PowerDsine
3001 Midspan
PowerDsine 3001 provides
Data Out & Power Out via
CAT-5 (blue cable) to port J1
of POE PD Evaluation Board
Copyright © 2008
Rev. 1.0, 2008-12-18
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 20