DI-37 [POWERINT]
16.5 W DC-DC Converter; 16.5 W¯¯ DC- DC转换器
| 型号： | DI-37 |
| 厂家： | 
Power Integrations |
| 描述： | 16.5 W DC-DC Converter |
| 文件： | 总2页 (文件大小：227K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Design Idea DI-37
™
DPA-Switch
16.5 W DC-DC Converter
Application
Device
Power Output
Input Voltage
Output Voltage
Topology
Telecom
DPA424R
16.5 W
36-75 VDC
3.3 V
Forward Sync. Rec.
Design Highlights
voltages and linearly reduces the maximum duty cycle with
input voltage to prevent core saturation during load transients.
Resistor R3 programs the DPA-Switch current limit to 60%
of nominal to limit fault and overload power. Drain voltage
clamping is provided by Zener diode VR1. Transformer core
reset is controlled by the gate capacitance of Q1.
•
•
•
•
•
Low cost
400 kHz synchronous rectification design
Low component count
Efficiency – 87% at 48 VDC
No current sense resistor or current transformer
required
Resistor R15 charges the gate of Q2, the forward synchronous
rectifier MOSFET. The catch synchronous rectifier MOSFET
(Q1) is directly driven by the transformer (T1) reset voltage and
operates only when Q2 is off. Diode D2 provides a conduction
path for the output inductor (L2) current when the transformer
reset is complete.
•
•
Output overload, open loop and thermal protection
Integrated UV meets ETSI standard
Operation
DPA-Switch greatly simplifies the design compared to a
discreteimplementation. ResistorR1programstheunder/over
C7
1 nF
R14
10 Ω
1.5 kV
L1
1 µH
2.5 A
C13
1 µF
0805
C10
C11
C12
+VIN
36-75 VDC
100 µF 100 µF 100 µF
L2
3.3 V, 5 A
6.3 V 6.3 V 6.3 V
R1
619 kΩ
1%
R15
10 Ω
D2
B540C
D1
BAV
Q1
Si4800
DY
19WS
RTN
T1
Q2
Si4800
DY
C4
4.7 µF
U2
R7
10 kΩ
20 V
R10
C1, C2
1 µF
3.24 kΩ
1%
100 V
DPA-Switch
C16
D3
U2
PC357N1T
100 nF
U1
D
L
BAV19WS
DPA424R
CONTROL
CO
R6
150 Ω
R12
5.1 Ω
C
R9
220 Ω
S
X
F
C15
R4
C14
1 µF
10 µF
1.0 Ω
VR1
SMBJ
150
10 V
C5
220 nF
U3
C6
68 µF
10 V
R3
R11
LM431AIM3
11.1 kΩ
10.0 kΩ
VIN
1%
1%
PI-3650-072004
Figure 1. DPA424R–16.5 W, 3.3 V, 5 A DC-DC Converter.
July 2004
DI-37
www.powerint.com
DI-37
Key Design Points
•
Transformer core reset is critical in this design. MOSFET
gate loading will affect the transformer reset waveform.
Capacitor CQ1gs will load transformer reset. Choose Q1
MOSFET such that CQ1gs provides sufficient reset at low
line and safe maximum drain voltage at high line.
Choose synchronous rectifier MOSFETs which have both
low RDS(ON) and also low Qg (combination of gate charge
Qgs and Miller capacitance Qgd).
•
•
•
Reduce transformer leakage inductance by filling each
winding layer across the entire width of the bobbin.
Choose a low-drop Schottky diode (such as Vishay
SL44 – Vf = 0.42 V), to increase high line efficiency.
Choose a larger DPA-Switch to increase efficiency at low
and medium input voltages.
•
TRANSFORMER PARAMETERS
INDUCTOR PARAMETERS
Epcos P/N: P 14 x 8 N87,
Epcos P/N: P 14 x 8 N87,
Core Material
Core Material
ungapped
gap for inductor
8-pin P 14 x 8 surface mount
8-pin P 14 x 8 surface mount
Bobbin
bobbin
Bobbin
bobbin
Primary 10T + 10T, 1 x 26 AWG
Winding Details
Main 10T, 2 x 24 AWG
Winding Details
3.3 V, 4 x 26 AWG
Bias 30T, 1 x 32 AWG
Winding Order
and Pin Numbers Primary-2 (NC-1)
Primary-1 (4-NC), 3.3 V (5-6),
Winding Order
and Pin Numbers Bias (1-2)
Pin (7,8-5,6): 16 µH ±10% at
400 kHz
Main (7,8-5,6)
Primary
Inductance
600 µH ±25% at 400 kHz
Inductance
Primary Resonant
Frequency
Table 2. Inductor Design Parameters.
3.8 MHz (minimum)
Leakage
Inductance
1 µH (maximum)
Table 1. Transformer Design Parameters.
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Power Integrations may make changes to its products at any time. Power Integrations has no liability arising from your use of any information, device or circuit
described herein nor does it convey any license under its patent rights or the rights of others. POWER INTEGRATIONS MAKES NO WARRANTIES HEREIN AND
SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATIONS, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS. The products and applications illustrated herein (including circuits external to the
products and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications
assigned to Power Integrations. A complete list of Power Integrations' patents may be found at www.powerint.com.
The PI logo, TOPSwitch, TinySwitch, LinkSwitch and EcoSmart are registered trademarks of Power Integrations. PI Expert and DPA-Switch
are trademarks of Power Integrations. Copyright 2004, Power Integrations
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B
7/04
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