DI-28 [POWERINT]
3 W Charger: <30 mW No-load Consumption; 3 W充电器： \u003c 30 mW的空载功耗
| 型号： | DI-28 |
| 厂家： | 
Power Integrations |
| 描述： | 3 W Charger: <30 mW No-load Consumption |
| 文件： | 总2页 (文件大小：49K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
Design Idea DI-28
TinySwitch®-II 3 W Charger:
<30 mW No-load Consumption
Topology
Flyback
Device
Power Output
Input Voltage
Output Voltage
Application
Charger
3 W
85-265 VAC
TNY264P
5 V, 600 mA
the internal current source at no-load. Other load conditions
are not important as the device will be powered from the
DRAIN pin if bias is lost, allowing a simple flyback winding
to be used. Figure 2 shows that the bias winding and choice
of R2 should provide approximately 550 µA at no-load to
minimize consumption.
Design Highlights
• Less than 30 mW no-load power consumption (for
115/230 VAC input)
• Meets CISPR-22 Class B without Y capacitor
• Low cost, low component count solution
The circuit meets CISPR-22 Class B conducted EMI limits
without aYcapacitorandthereforehasverylowACleakage
current. TinySwitch-II frequency jitter, use of the bias
winding as a shield and capacitor C3 to soften leakage
inductance spikes combine to provide the EMI performance.
Operation
The TinySwitch-II flyback converter in Figure 1 generates a
constant voltage, constant current (CV/CC) 5 V,
600 mA output. Typical applications include wall-mounted
chargers for cell phones, PDAs and other battery powered
portable equipment.
Key Design Points
The key performance characteristic of the circuit shown is the
extremely low no-load consumption of <30 mW. A linear
transformer charger of similar rating will typically consume
1 W to 4 W at no-load. At $0.12/kWh, the TinySwitch-II can
therefore reduce energy costs by $1 to $4 per year.
• Design bias winding circuit to provide approximately
550 µA at no-load. Figure 2 shows the details.
• Minimizesecondarycircuitbiascurrents. Uselowcurrent
feedback Zeners for best tolerance. The very low bias
current in this design will provide approximately ±10%
output voltage tolerance. A precision reference (e.g.
TL431) can be used to reduce this if required.
• Designtransformerwithlowreflectedvoltagetominimize
clamp losses. A bigger device (TNY266) may help to
further reduce VOR.
• Wind transformer for lowest leakage inductance. Choose
wire gauges to completely fill winding layers.
• Winding transformer with tape between primary layers
further reduces intra-winding capacitance and no-load
consumption.
The no-load performance is achieved by using a transformer
biaswindingasalowvoltagesourceforTinySwitch-IIoperating
current. Even without this winding, a TinySwitch-II circuit will
consume <300 mW at no-load. However, by providing external
bias, the internal high voltage current source, which normally
powers the IC from the DRAIN pin, is disabled and a further
reduction in consumption is therefore achieved.
Thebiaswindingshouldprovideenoughcurrenttofullydisable
D7 11DQ06
1
8
+5 VDC
L3
C6
L1
1.0 mH
8T
24 AWG
Ferrite
Bead
C3
470 µF
10 V
2.2 nF
R3
1.5 kΩ
VR1
BZY97C200
1 kV
7
3
D6 1N4148
D1
D2
105T
33 AWG
RF1
8.2 Ω
1.0 W
1N4005 1N4005
C7
D5
1N4937
13T x2
31 AWG
4
R2
5.1 kΩ
C5
100 µF
2
47 µF
Q1
2N3906
10 V
16 V
L
C2
4.7 µF
400 V
C1
4.7 µF
400 V
85 - 265
VAC
TinySwitch-II
VR3
BZX79B5V1
U1
R4
820 Ω
TNY264P
N
D
S
EN
BP
U2
D3
1N4005
D4
1N4005
L2
Bead
2.2 µH
C4
0.1 µF
50 V
R5
2.7 Ω
2 W
U2
PC817A
RTN
PI-3079-091402
Figure 1. TinySwitch-II 3.0 W Cell Phone Charger.
September 2002
DI-28
www.powerint.com
DI-28
30
25
80
70
60
20
15
115 VAC
230 VAC
50
40
30
10
5
20
10
0
0
85 110 135 160 185 210 235 260
300 400 500 600 700 800 900
Input Voltage (VAC)
BYPASS Pin Current (µA)
Figure 3. No-load Input Power vs. Line Voltage.
Figure 2. No-load Input Power vs. BYPASS Pin Current.
6
5
TRANSFORMER PARAMETERS
EE13
TDK PC40, or equivalent
AL of 128 nH/T2
Core Material
Bobbin
4
115 VAC
230 VAC
EE13, 8 pin
3
Primary (1-2), tape,
Bias (3-4), tape,
Secondary (7-8), 5 V, tape
Winding Order
(pin numbers)
2
1
Primary Inductance
1.9 mH ±10%
500 kHz (minimum)
50 µH (maximum)
Primary Resonant
Frequency
0
0
100 200 300 400 500 600 700
Leakage Inductance
Output Current (mA)
Table 1. Transformer Construction Information.
Figure 4. 5.0 VDC, 600 mA CV/CC Curve.
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.
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