Features
• DC-DC forward converter based on PM8804
• Input voltage range: 42 – 56 VDC
• Switching frequency: 250 kHz
• Output:
– Power: 100 W
– Voltage: 5 VDC
– Current: up to 20 A
• Peak efficiency > 94%
• Open circuit protection
• RoHS complaint
• WEEE compliant
Description
The STEVAL-ISA204V1 evaluation board is designed to demonstrate high efficiency
DC-DC conversion, able to output 100 W (5 V/20 A) from 42 to 56 V DC input, which
is especially suitable for telecom applications.
The power conversion stage is based on an active clamp forward topology managed
by a PM8804 PWM controller featuring all the integrated circuitry necessary for a
compact and efficient 48 V converter. The highly configurable controller includes a
programmable oscillator for switching frequency regulation up to 1 Mhz, adjustable
slope compensation, dual complementary low-side drivers with programmable dead
time, programmable soft start, soft turn off and a programmable current sense
blanking time.
Product summary
100W 5V/20A forward
converter based on
PM8804 PWM controller
STEVAL-
ISA204V1
PWM peak current
mode controller for PoE
and telecom systems
PM8804
Application Server &
Telecom Power
100W 5V/20A active clamp forward converter based on PM8804 for telecom
systems
STEVAL-ISA204V1
Data brief
DB3958 - Rev 1 - June 2019
For further information contact your local STMicroelectronics sales office.
www.st.com
1Application overview
The STEVAL-ISA204V1 represents a forward converter application with synchronous rectification for 48 V
auxiliary power supplies destined for server and telecommunications equipment. The board can supply an output
current up to 20 A.
The PM8804 integrates two MOSFET drivers with up to 1 A peak sink current capability. The GAT1 signal drives
the main switching MOSFET, while the GAT2 signal controls a P-channel MOSFET referred to PGND in active
clamp forward topology.
The synchronous rectification stage can be paralleled by mounting two further STL160N4F7 N-channel MOSFETs
(Q2 and Q8), which can significantly reduce the operating temperatures of the mounted synchronous rectifier
MOSFETs.
Figure 1. STEVAL-ISA204V1 block diagram
Input
Filter
PM8804
Feedback
Circuit
(TS431AILT)
Output
Filter
48V
Input
Feedback
VCC
Output
5V 20A
N-channel Mosfet
PWM peak current
mode
controller for
telecom systems
Load
Adjustable shunt
Voltage Reference
Synchronous
Rectification
Forward Converter
Optocoupler
Active Clamp
Reset
GAT1
GAT2
RELATED LINKS
Visit the Server & Telecom application page for more information on relevant power supply and conversion strategies
STEVAL-ISA204V1
Application overview
DB3958 - Rev 1 page 2/7
2Electrical and efficiency characteristics
Table 1. Electrical specifications of STEVAL-ISA204V1
Electrical specifications Range / Value
Input voltage range 42 – 56 V DC
Output voltage 5 V
Output current 20 A
Total output power 100 W
Maximum efficiency > 94 %
The STEVAL-ISA204V1 evaluation board attains a maximum efficiency of 94%. The figure below shows the
efficiency of the board at different input voltages and load conditions.
Figure 2. Efficiency at different load conditions
Efficiency %
Load %
48 V
56 V
42 V
10 20 30 40 50 60 70 80 90 100
84
86
88
90
92
94
96
Table 2. STEVAL-ISA204V1 MOSFET temperatures at maximum load (20 A)
Optional Q2 and Q8 Synchronous rectifier Q1 Synchronous rectifier Q5 Forward Converter Q4
unmounted 84 °C 94.4°C 74 °C
mounted 74 °C 77.8 °C 73 °C
STEVAL-ISA204V1
Electrical and efficiency characteristics
DB3958 - Rev 1 page 3/7
3Board layout
Figure 3. STEVAL-ISA204V1 top layer
Figure 4. STEVAL-ISA204V1 bottom layer
STEVAL-ISA204V1
Board layout
DB3958 - Rev 1 page 4/7
4Schematic diagram
0805
R30
240K
C59220pF
16V
8x10.5
C43
330uF
1%
R41 NM
100V
0805
C46
1nF
0603
25V
C50
100nF
25V
0603
C47
2.2uF
0805
R32
10R
0603
R25
10K
0805
R38
10R
J4
0805
R36
10R
1 2
L1
Wurth 74439346056
4 1
23
U3
FOD817AS C57
22nF
0805
R61
3.3K
1210
100V
C33
4.7uF
1%
R54
15K
2KV
1812
C20 NM
SOT23
Q3
MMBT3904LT1-NM
35
4
12
SOT23-5
U4
TS431AILT
A C
NC
SOT23
D11
BZX84C10-NM
0603
R31
NM 0603
C44
100nF
0805
C28
NM
1%
R52
20k
2KV
1812
C54 2.2nF
R47
0E
0805
R62
5.6K
R48 10R
SOD323
D13
BAS16J
J6
R40
10K
C56
NM
C60
22nF
0805
C30
NM
SOD323
D9
BAS16J
1 2
L4
SER2013-362L
1210
16V
C36
47uF
100V
1210
C24
4.7uF
1210
100V
C32
4.7uF
1%R53
4.7K
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q4
BSC190N15NS3
0603
25V
C55
100nF
4
1
2
5
7
11
8
12
10
9
3
6
T3
RA7129-BL
D15
VOUT Led
1210
R44
0R05
10x10.2
100V
C29
33uF
R51
560R
1%
R43130K
0603
R28
0R
0603
25V
C25
100nF
R50
220R
C5333nF
100V
1210
C31
4.7uF
1%
R55
12k
100V
0805
C51
1nF
C52
NM
SGND
SGNDPGND
PGND
Input Filter
EEEFK2A330P
TP10
Turret
TP11
Turret
TP5
TP-Red
TP6
TP-Black
2 8
4 10
5
1
6
T4
POE120PL-xxL_-NM
NC2 7
AGND
1
BLK
16
GAT1 9
PGND 10
PGD 6
FSW
4
SS
2
MODE
13
CS
14
CTL
15
GAT2 11
VC 12
DT
3
VIN 8
NC1 5
Ex Pad 17
U2
PM8804
PGND
PGND
AGND
Power circuit
Auxiliary voltage
SOD323
D48
BAS16J
0603
25V
C45
100nF
1206
R78
0R
TP12
TP-Red
1%
R46 91K
1%R45 270K
TP7
TP-Red
SOD323
D12
BAS70
1210
R108
0R05
200V
1206
C48
47nF 1206
R15
NM
200V
1206
C49
NM
1 2
L9
LPS4018-105ML
GSL
SGND
VSN VSP
SGND
GSH
GSL GSHVSN
VSP
VSP
VSN
SOT23
Q10
PBSS5240T-NM
SGND
SGND
AGND
SGND
SGND
Feedback circuit
Synchronous rectifiers
TP13
TP-Red
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q5
STL160N4F7
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q1
STL160N4F7
TP14
TP-Red
100V
0805
C95
1nF
100V
0805
C39
1nF
0805
R124
10R
0603
25V
C58
100nF
SOD323
D50
BAS70
SOD323
D49
BAS70
25V
0603
C96
2.2uF
R125
47K
TP8
TP-Red
TP9
TP-Black
1210
16V
C40
47uF
1210
16V
C41
47uF
1210
16V
C37
47uF 1210
16V
C42
47uF
1210
16V
C38
47uF
A C
NC SOT23
D2
BZX84C10
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q2
NM
SOD323
D1 BAS16J
SOT23
Q9
PBSS4240T
0603
R37
10K
0805
R29
1K
0805
R17
22R
0805
R16
NM
50V
0805
C75
100pF
0805
R33NM
SOD323
D16 BAS16J
SOT23
Q12
PBSS4240T
SOT23
Q11
PBSS5240T-NM
A C
NC SOT23
D17
BZX84C10
0805
R34
22R
0805
R35
1K
50V0805
C76 100pF
0603
R56
10K
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q8
NM
13
2
SOT23
U12
NM
INPUT 48 V
O U T P U T 5 V / 2 0 A
Gate Driving of MOSFET
100W - 48V TO 5V - FORWARD CONVERTER BASED ON PM8804
1
2
P1
Header 2
5.6uH
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 3x3
Q7
FDMC86259P
G4
D5S1
S2
S3 D6
D7
D8
powerFLAT 5x6
Q6
FDMS86263P - NM
0805
R49
0E
TP18
TP-Yellow
Note: Q6 - Do not Mount
DB3958 - Rev 1 page 5/7
STEVAL-ISA204V1
Schematic diagram
Revision history
Table 3. Document revision history
Date Version Changes
14-Jun-2019 1 Initial release.
STEVAL-ISA204V1
DB3958 - Rev 1 page 6/7
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© 2019 STMicroelectronics – All rights reserved
STEVAL-ISA204V1
DB3958 - Rev 1 page 7/7
