Power DI-24 30 w dc-dc converter Datasheet

®
Design Idea DI-24
®
DPA-Switch
30 W DC-DC Converter
Application
Device
Power Output
Input Voltage
Output Voltage
Topology
DC-DC Converter
DPA424R
30 W
36-75 VDC
5V
Forward
Design Highlights
•
•
•
•
•
•
•
•
Resistor R3 programs the internal DPA424R current limit to
85% of nominal, just above the level needed at full load,
limiting overload power. This feature also allows a larger
DPA-Switch to be selected, without requiring any other
circuit changes. A larger DPA-Switch reduces conduction
losses, raising efficiency.
Extremely low component count
High efficiency – 85% using Schottky rectifiers
No current sense resistor or current transformer required
Output overload, open loop and thermal protection
Accurate input under/over voltage meets ETSI standards
Operates to zero load
400 kHz operation minimizes size of magnetics
Available for prototyping in DAK-21
Capacitors C8 and C9 provide transformer core reset; C8 also
limits the leakage inductance spike on the DRAIN. Resistor
R5 in series with C9 damps ringing. Zener diode VR1
provides a hard voltage clamp to limit DRAIN voltage, but is
only active during transients and overload conditions.
Operation
DPA-Switch greatly simplifies the design compared to a discrete
implementation. Resistor R1 programs the input under/over
voltages to 33 V and 86 V, respectively, and linearly reduces the
maximum duty cycle with input voltage to prevent core saturation
during load transients. These thresholds have tolerances that
guarantee the converter is operational at 36 V, without the cost
of additional line sense components.
C7 1 nF R14
1.5 kV 10 Ω
+VIN
36-75 VDC
L1
1 µH 2.5 A
1
C8
47 pF
200 V
R1
619 kΩ
1%
The bias supply for U1 is provided from an auxiliary winding
on output inductor L2. This gives higher efficiency than a
transformer winding, since it provides a fixed voltage
independent of input voltage. Pre-load R13 maintains the
bias voltage ≥8 V at zero load.
On the secondary, a soft finish network, C13, D3 and R7,
eliminates output turn-on overshoot. The remaining
components provide output voltage regulation and loop
compensation.
C9
2.2 nF R5
50 V 1.0 Ω
T1
L2
8 µH 6 A
5,6
7,8
4
C2
1 µF
100 V
5,6
D2
MBRB2545CT
U1
DPA424R
S
VR1
SMBJ
150
U2
L
CONTROL
X
F
C
R3
8.25 kΩ C5
1% 220 nF
-VIN
R4
1.0 Ω
C6
68 µF
10 V
C12
1 µF
10 V
5 V, 6 A
RTN
U2
R7
10 kΩ
D3
BAV19WS
R6
150 Ω
C13
10 µF
10 V
U3
LM431AIM3
R10
10.0 kΩ
1%
C16
100 nF
R12
5.1 Ω
R9
220 Ω
C14
1 µF
R11
10.0 kΩ
1%
PI-2993-090602
Figure 1. DPA-Switch 30 W DC-DC Converter.
DI-24
D1
BAV19WS
DPA-Switch
D
R13
160 Ω
1
C4
4.7 µF
20 V
C3
1 µF
100 V
C11
100 µF
10 V
7,8
3
2
C1
1 µF
100 V
C10
100 µF
10 V
www.powerint.com
September 2002
DI-24
Key Design Points
• For nominal under-voltage set point VUV:
R1 = (VUV-2.35 V)/50 µA. VOV = (R1×135 µA)+2.5 V.
• Select C9 such that the core resets at VUV and the DRAIN
voltage ≤170 V at VOV. To reduce leakage spike, C8 may
be added, adjusting C9 accordingly.
• Zener VR1 safely limits the DRAIN voltage below BVDSS
and guarantees transformer reset.
• Opto U2 should have a CTR of between 100% and 200%
for optimum loop stability.
• At zero load, maximum input voltage, the bias voltage
across C4 should be ≥8 V (12 V to 15 V under nominal
conditions).
Efficiency (%)
85
TRANSFORMER PARAMETERS
Core
PR1408
Siemens N87 material, ungapped
Bobbin
P1408 8 pin (B&B B-096 or equivalent)
Winding Order
(pin numbers)
Primary: 7T + 8T, 27 AWG
Secondary: 4T x 27 AWG
Primary (4-3), tape, Secondary
(5,6-7,8), Tape, Primary (3-1),tape
Inductance
Primary: 450 µH ± 25%, Leakage 1 µH (max)
Primary Resonant
Frequency
3.8 MHz (minimum)
Winding Details
PI-2995-073002
90
• Good layout practices should be followed:
- Locate C5, C6 and R4 close to U1, with grounds returned
to the SOURCE pin.
- Primary return should be connected to the DPA-Switch
tab, not the SOURCE pin.
- Minimize the primary and secondary loop areas to reduce
parasitic leakage inductance.
• Consult AN-31 and EPR-21 for additional design tips and
information.
80
75
Table 1. Transformer Construction Information.
70
VIN = 36 V
VIN = 48 V
VIN = 60 V
VIN = 72 V
65
OUTPUT INDUCTOR PARAMETERS
60
0
10
20
30
PR1408 Siemens N87 material
Gap for AL of 163 nH/T2
Core
40
Bobbin
P1408 8 pin (B&B B-096 or equivalent)
Winding Details
Bias: 18T, 32 AWG, Main: 7T, 2x24 AWG
Winding Order
(pin numbers)
Inductance
Pins 5,6-7,8
Output Power (W)
Figure 2. Efficiency vs. Output Power.
Bias (1-2), tape, Main winding (7,8-5,6), tape
8 µH ± 10%
Table 2. Output Inductor Construction Information.
For the latest updates, visit our Web site: www.powerint.com
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability.
Power Integrations does not assume any liability arising from the use of any device or circuit described herein, nor does it convey any
license under its patent rights or the rights of others. The products and applications illustrated herein 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 and EcoSmart are registered trademarks of Power Integrations, Inc.
PI Expert is a trademark of Power Integrations, Inc. ©Copyright 2002, Power Integrations, Inc.
WORLD HEADQUARTERS
AMERICAS
Power Integrations, Inc.
San Jose, CA 95138 USA
Customer Service:
Phone:
+1 408-414-9665
Fax:
+1 408-414-9765
e-mail: [email protected]
CHINA
Power Integrations International
Holdings, Inc.
China
Phone:
+86-755-8367-5143
Fax:
+86-755-8377-9610
e-mail: [email protected]
A
9/02
EUROPE & AFRICA
Power Integrations (Europe) Ltd.
United Kingdom
Phone:
+44-1344-462-300
Fax:
+44-1344-311-732
e-mail: [email protected]
SINGAPORE
Power Integrations, Singapore
Republic of Singapore 308900
Phone:
+65-6358-2160
Fax:
+65-6358-2015
e-mail: [email protected]
KOREA
Power Integrations
International Holdings, Inc.
Seoul, Korea
Phone:
+82-2-782-2840
Fax:
+82-2-782-4427
e-mail: [email protected]
JAPAN
Power Integrations, K.K.
Keihin-Tatemono 1st Bldg.
Japan
Phone:
+81-45-471-1021
Fax:
+81-45-471-3717
e-mail: [email protected]
APPLICATIONS HOTLINE
World Wide +1-408-414-9660
www.powerint.com
TAIWAN
Power Integrations
International Holdings, Inc.
Taipei, Taiwan
Phone:
+886-2-2727-1221
Fax:
+886-2-2727-1223
e-mail: [email protected]
INDIA (Technical Support)
Innovatech
Bangalore, India
Phone:
+91-80-226-6023
Fax:
+91-80-228-9727
e-mail: [email protected]
APPLICATIONS FAX
World Wide +1-408-414-9760
Similar pages