Power DI-118 4.5 w cv/cc charger with <260 mw no-load consumption Datasheet

Design Idea DI-118
®
TinySwitch-III
4.5 W CV/CC Charger with <260 mW
No-Load Consumption
Application
Device
Power Output
Input Voltage
Output Voltage
Topology
Charger
TNY276P
4.5 W
90-265 VAC
5.7 V, 800 mA
Flyback
Design Highlights
•
•
•
•
•
•
•
When the primary current reaches the MOSFET current limit,
the controller turns it off, and the energy in T1 is transferred
to the output. Schottky diode D6 and capacitor C5 rectify
and filter the output. Inductor L3 and capacitor C7 attenuate
the switching ripple on the output.
Simple, low cost, low parts count CV/CC solution
Low input power at no-load: <260 mW at 265 VAC
Efficiency >65% at 90 VAC
Meets CEC / ENERGY STAR requirements for active
mode efficiency (66.8 % vs 62.6 % requirement)
Compact design using small, low cost EE16 core size
>15 dBµV margin to EN55022B conducted EMI limits
No Y-capacitor: <10 µA line frequency leakage current
The primary clamp (D5, R2, C4 and R1) limits the maximum
peak drain voltage to less than the 700 V BVDSS rating of
the internal MOSFET. Resistor R2 reduces high-frequency
leakage inductance ringing and thereby EMI. The tightly
controlled tolerances of U1 allow this configuration to still
meet low no-load input power levels.
Operation
The CV/CC charger circuit shown in Figure 1 was designed
as a Flyback converter, using TNY276P (U1). The device
has its four SOURCE pins on one side of its 8-pin package,
which simplifies the layout of the PCB copper for heatsinking.
Additionally, the value of C3 selects the reduced current limit
of U1. Both factors allow U1 to deliver full power from within
a sealed enclosure, at an external ambient temperature of
40 °C. In less thermally challenging applications, a TNY275P
operating at its standard current limit (C3 = 0.1 µF) could be
used to reduce cost, without any other changes.
The pi filter formed by C1, L1, L2 and C2 attenuates conducted
EMI while C8 and R8 on the secondary side reduce high
frequency ringing. The integrated frequency jitter feature
of U1 along with E-ShieldTM techniques allow such simple
EMI filtering to ensure compliance with EN55022B, even
without a Y capacitor across the primary to secondary
isolation barrier.
The output is regulated using optocoupler feedback.
During CV operation, reference IC U3 senses the output
The internal MOSFET within U1 conducts current through the
primary winding of T1 during each enabled switching cycle.
L1
1 mH
D1
1N4005
RF1
8.2 Ω
2.5 W
D2
1N4005
90-265
VAC
D3
1N4005
1
C4
1 nF
1 kV
C1
4.7 µF
400 V
C8
1 nF R8
50 V 10 Ω
R1
200 kΩ
NC NC
2
7
3,4
C2
4.7 µF
400 V
10
R3
1.2 Ω
2W
L2
Ferrite
Bead
S
RTN
R4
100 Ω
U2-B
R7
13.7 kΩ
1%
C6
100 nF
50 V
EN/UV
5.7 V,
800 mA
C7
100 µF
10 V
T1
EE16
TinySwitch-III
U1
TNY276P
D
L3
Ferrite Bead
3.5 × 7.6 mm
D6
SB260
R2
100 Ω
D5
1N4007GP
D4
1N4005
C5
470 µF
10 V
R5
1 kΩ
BP/M
S
C3
1 µF
50 V
Figure 1. 4.5 W, 5.7 V CV/CC Charger Using TNY276P.
DI-118
U2-A
PC817A
U3
TL431
R6
10 kΩ
1%
PI-4422-051006
September 2006
DI-89 DI-118
•
For consistent EMI performance in production,
manufacturing variations in transformer T1 must be
minimized from unit to unit. This is especially important
in designs that do not use a Y-capacitor.
Place tape between the primary winding layers to reduce
intra-winding capacitance. This will help reduce the
no-load consumption.
•
Key Design Points
80
70
Winding Details
Winding Order
(pin numbers)
Inductance
AV
50
40
30
20
10
0
EE16, NC-2H material or equivalent, gap for ALG of 156 nH/T2
-10
5+5 pin horizontal
-20
0.15
Shield: 28T, 2 × 33 AWG
Primary: 120T, 33 AWG
Shield: 8T, 2 × 27 AWG
5.7 V: 10T, 25 AWG T.I.W.
Shield (3-NC), tape,
primary (2-1), tape,
shield (NC-3), tape,
5.7 V (10-7), tape
Primary: 2.25 mH ±12%
Leakage: 45 µH (max)
Primary Resonant
850 kHz (min)
Frequency
Table 1. Transformer Design Parameters.
T.I.W.: Triple Insulated Wire, NC: No Connection
1.0
10.0
100.0
MHz
Figure 2. Worst-Case Conducted EMI (Output RTN Connected
to Artificial Hand Input of LISN).
Output Voltage (VDC)
Bobbin
QP
60
TRANSFORMER PARAMETERS
Core Material
EN55022B Limits
6.5
6
5.5
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
PI-4423-050906
•
Verify that the maximum drain voltage is <650 V at high
line and maximum overload condition. Adjust the values of
R1 and C4 as necessary. However, avoid making the clamp
circuit too large (ie. low value of R1 and high value of C4),
as this will increase the no-load power consumption.
Selecting a fast diode vs. an ultra-fast diode for D5 will
improve efficiency by recovering leakage energy. If glass
passivated (1N4007GP) is unavailable a FR107 may be used.
dBµV
•
PI-4421-050906
voltage via R6 and R7 and drives the optocoupler. However,
the control shifts to CC mode of operation when the voltage
across R3 exceeds the forward drop of the photo-diode in U2.
TinySwitch-III allows this simple CC sensing scheme to be used,
while still meeting active mode efficiency requirements.
115 VDC
230 VDC
Low Limit
High Limit
0
100
200
300
400
500
600
700
800
900
Output Current (mA)
Figure 3. Typical Output Characteristics.
For the latest updates, visit 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. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL
WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS. The products and applications
illustrated herein (transformer construction and circuits external to the products) 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. Power Integrations grants its
customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm.
Power Integrations
5245 Hellyer Avenue
San Jose, CA 95138
Phone: 1-408-414-9200
Apps: 1-408-414-9660
Apps Fax: 1-408-414-9760
The PI logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, PeakSwitch, EcoSmart,
Clampless, E-Shield, Filterfuse, PI Expert and PI FACTS are trademarks of Power Integrations, Inc.
Other trademarks are property of their respective companies. ©Copyright 2006, Power Integrations, Inc.
For a complete listing of worldwide
sales offices, please visit
www.powerint.com
Rev. A 09/06
www.powerint.com
Similar pages