DI-78
•
•
Select the initial value of R9 using: R9 = VF(U2)/IO. Small
adjustments may be made by changing the value of R8.
Use an optocoupler with a high CTR (300% to 600%) to
improve CC linearity and variability.
For VR1 select a Zener series with a low test current.
Inductor L2 and C7 are typically not required for battery
loads.
Key Design Points
•
Diode D5 should be a glass passivated type to guarantee a
specified recovery time and should be used with R2 fitted
to limit reverse pull-out current.
•
•
•
Select the value of C1 and C2 to meet differential line surge
withstand requirements.
80
70
250
225
200
175
QP
AV
60
50
150
125
100
75
40
Quasi Peak
30
20
10
50
0
25
Average
-10
0
0
50
100 150 200 250 300
-20
0.15
Input Voltage (VAC)
1.0
10.0
70.0
MHz
Figure 4. No-Load Input Power vs. Line Voltage.
Figure 2. Conducted EMI Plot, 230 VAC Input, Maximum Load and
Output Return Connected to Artificial Hand Input of LISN.
TRANSFORMER PARAMETERS
EP10 (TDK PC40), gapped for
Core Material
6
5
AL of 54.1 nH/T2
Bobbin
EP10 Horizontal, 8-pin
Shield 1: 23T, 38 AWG x 2, tape,
Primary: 129T, 38 AWG, tape,
Winding Details Shield 2: 10T, 31 AWG x 2, tape,
Secondary: 11T, 32 AWG triple
insulated, tape
4
Low Limit
High Limit
85 VAC
3
265 VAC
2
Primary
900 µH ±5%
Inductance
1
0
Primary Resonant
900 kHz (minimum)
Frequency
0
80
160
240
320
400
Leakage
70 µH (maximum)
Inductance
Output Current (mA)
Figure 3. V-I Output Characteristic.
Table 1. Transformer Design Parameters.
For the latest updates, visit www.powerint.com
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, DPA-Switch and EcoSmart are registered trademarks of Power Integrations. PI Expert and
PI FACTS are trademarks of Power Integrations. Copyright 2004, Power Integrations
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