View DI-27_1232640.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

Design Idea DI-27 (R) TinySwitch 3 W AC Adapter:
<10 mW No-load Consumption
Application Adapter Device TNY254 Power Output 3W Input Voltage 85-265 VAC Output Voltage 12 V
(R)
Topology Flyback
Design Highlights
* Extremely low no-load power consumption (<10 mW at 115/230 VAC input) * Simple RC snubber/clamp reduces EMI * Low cost, low component count solution
consume <100 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. The bias winding should provide enough current to fully disable the internal current source. Figure 2 shows that the bias winding and choice of C5 and R3 should provide 250 A to 300 A at no-load to minimize consumption. Zener VR3 is required to clamp the BYPASS pin voltage. The output Zener VR2 is not biased, minimizing the secondary circuit consumption. A low current Zener therefore provides the best output voltage tolerance. Components R2 and C3 provide a low cost clamp and also help reduce EMI by softening switching edges. This type of snubber increases switching losses and would therefore normally be avoided in low consumption circuits. However, with TinySwitch, these losses are negligible at no-load as switching frequency is so low. This is illustrated in Figure 3 where replacing R2 and C3 with a Zener clamp across the primary winding reduces consumption by <0.25 mW.
C8 2.2 nF Y1 1 10 D6 UF4003 49T 28 AWG D5 1N4148 C5 100 F 10 V R3 4.7 k VR2 BZX79B11 C6 180 F 16 V L2 Ferrite Bead +12 VDC C7 100 F 16 V RTN
Operation
The TinySwitch flyback converter in Figure 1 generates an isolated 12 VDC, 3 W output from 85 VAC to 265 VAC input. Typical applications include wall mounted AC adapters for consumer products. The key performance characteristic of the circuit shown is extremely low no-load consumption of <10 mW. A linear transformer adapter of similar rating will typically consume 1 W to 4 W at no-load. At $0.12/kWh, the TinySwitch can therefore reduce energy costs by $1 to $4 per year. The no-load performance is achieved using a transformer bias winding as a low voltage source for TinySwitch operating current. Even without this winding, a TinySwitch circuit will
D1 & D2 1N4007 RF1 8.2 L 85 - 265 VAC
L1 1.0 mH 223T 36 AWG R1 4.7 k 9 3
2
30T x2 4 37 AWG
C1 & C2 3.3 F 400 V
R2 1.5 k 1/2 W
D
TinySwitch
U1 TNY254P
EN/UV BP
N D3 & D4 1N4007 C3 68 pF 1 kV
S
C4 0.1 F 50 V
U2 PC817A
VR3 BZX79B6V2
U2
Figure 1. 3 W AC Adapter with <10 mW No-load Consumption.
DI-27
PI-3011-091802
www.powerint.com
September 2002
DI-27
PI-3297-090402
Key Design Points
* Design bias winding circuit to provide 250 A to 300 A at no-load. * Ensure C5 is large enough to supply above current at the very low no-load switching frequencies. * Minimize secondary circuit bias currents. Use low current feedback Zeners for best tolerance. * Zener or RCD clamp can be used to slightly reduce no-load consumption further. Use a 200 V Zener or maximize resistor value in RCD clamp for lowest losses. * Design transformer with low reflected voltage to minimize clamp losses. * Wind transformer for lowest leakage inductance. Choose wire gauges to completely fill winding layers. * Wind transformer with tape between primary layers to further reduce intra-winding capacitance.
PI-3010-080102
10
No-load Input Power (mW)
8
6
Zener Clamp RC Clamp
4
2
0 80 120 160 200 240
AC Line Voltage (A)
Figure 3. No-load Input Power Variation with Input Voltage.
100
TRANSFORMER PARAMETERS
Core Material EE16 Nippon Ceramic NC-2H AL of 74 nH/T2 EE16 10 pin (Ying Chin YC1607 or equivalent) Primary (1-2), Tape 12 V (10-9), Tape Bias (3-4), Tape 3.67 mH 10% 500 kHz (minimum) 300 H (maximum)
No-load Input Power (mW)
VIN = 100 VAC VIN = 230 VAC
Bobbin
10
Winding Order (pin numbers) Primary Inductance
1 0 100 200 300 400 500
Primary Resonant Frequency
BYPASS Pin Current (A)
Leakage Inductance
Figure 2. No-load Input Power vs. BYPASS Pin Current.
Table 1. Transformer 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. (c)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: usasales@powerint.com CHINA Power Integrations International Holdings, Inc. China Phone: +86-755-8367-5143 Fax: +86-755-8377-9610 e-mail: chinasales@powerint.com EUROPE & AFRICA Power Integrations (Europe) Ltd. United Kingdom Phone: +44-1344-462-300 Fax: +44-1344-311-732 e-mail: eurosales@powerint.com KOREA Power Integrations International Holdings, Inc. Seoul, Korea Phone: +82-2-782-2840 Fax: +82-2-782-4427 e-mail: koreasales@powerint.com SINGAPORE Power Integrations, Singapore Republic of Singapore 308900 Phone: +65-6358-2160 Fax: +65-6358-2015 e-mail: singaporesales@powerint.com JAPAN Power Integrations, K.K. Keihin-Tatemono 1st Bldg. Japan Phone: +81-45-471-1021 Fax: +81-45-471-3717 e-mail: japansales@powerint.com APPLICATIONS HOTLINE World Wide +1-408-414-9660 TAIWAN Power Integrations International Holdings, Inc. Taipei, Taiwan Phone: +886-2-2727-1221 Fax: +886-2-2727-1223 e-mail: taiwansales@powerint.com INDIA (Technical Support) Innovatech Bangalore, India Phone: +91-80-226-6023 Fax: +91-80-228-9727 e-mail: indiasales@powerint.com APPLICATIONS FAX World Wide +1-408-414-9760
A 9/02
www.powerint.com

▲Up To Search▲

Price & Availability of DI-27

	To Download DI-27 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .