RT7302 Flyback T8 18W

RT7302 Evaluate Report
for T8 Internal Power
(Flyback)
ACDC BU / SLM Division
Mar. 2016
http://www.richtek.com/LED
CONFIDENTIAL
RT7302 Brief introduction
RT7302 is an active power factor correction controller specifically
designed for using as a constant current LED driver.
Supporting:
Isolation: PSR mode
Non-isolation: Buck-Boost mode
Applications
AC/DC LED lighting driver
………
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CONFIDENTIAL
RT7302 Features
Primary-Side Regulation PWM Controller and
High PF LED Driver
• Primary Side Regulation(PSR)
• Power Factor Correction(PFC)
• Compatible with TRIAC Dimmer
• Built-in HV start-up Device
• Critical conduction mode(CRM)
• Max/Min switch frequency clamping
• Max/Min on time limitation
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CONFIDENTIAL
RT7302 Advantage
• Universal input voltage. (90Vac~264Vac)
• Good LED current regulation.
• No shunt regulator and photo to achieve the 2 nd regulation.
• Protection:
a. Open-circuit protection
b. Short-circuit protection
c. Output diode short-circuit protection
d. Vdd under/over voltage protection
e. Over temperature protection
f . Cycle-by-cycle current limitation
g. Excellent PF and THD.
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CONFIDENTIAL
Circuit
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CONFIDENTIAL
Electrical Performance
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CONFIDENTIAL
Efficiency
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CONFIDENTIAL
Power Factor
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CONFIDENTIAL
Current regulation
Limit in 1.23%
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CONFIDENTIAL
Load regulation
Frequency
Vac [V]
Vout [V]
Iout [mA]
60Hz
60Hz
60Hz
50Hz
50Hz
50Hz
110
42.79
45.80
49.52
43.11
46.23
49.73
407
404
403
403
400
399
110
110
230
230
230
Load regulation
0.98%
0.99%
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CONFIDENTIAL
PCB layout
Top Trace
Bottom Trace
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CONFIDENTIAL
Demo board photo
L
LED-
N
LED+
Length
Width
Height
229mm
18mm
10mm
PCB No : PCB022_V1
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CONFIDENTIAL
BOM
Item
Location
Value
Type
1
F1
T1.25A/300V
SS-5F-2P
2
RV1
7N471K
TVS-2P
3
LX2
30mH
LRS-T14
4
CX1
0.1uF
CFS-12X12
5
LX1
5mH
LDS-D9X12
6
BD1
1A/600V
DB-1A
7
C4
0.1uF/500V
CFS-11X10
8
R6,R7,R9
2.2Mohm
0805
9
R19
43kohm
0603
10
C6
22nF/50V
0603
11
C7
2.2uF/25V
0805
12
R22
0ohm
0603
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CONFIDENTIAL
BOM
Item
Location
Value
Type
13
R8
10kohm
1206
14
R2
140kohm
1206
15
D2
FM4007
SOD123
16
C2
2.2nF/1kV
1206
17
R13
200R
0805
18
D4
1N4148
SOD-123
19
Q1
4A/600V
TO-220
20
C9
100p/1kV
1206
21
LX3
T3.5*3*1.4
---
22
R15,R16,R17
2.21ohm
1206
23
R14
2kohm
0603
24
C10
470p/1kV
1206
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CONFIDENTIAL
BOM
Item
Location
Value
Type
25
CY1
1000pF/250Vac
CAP-10mm
26
R10
60kohm
0603
27
R18
8.06kohm
0603
28
C5
22pF
0603
29
D3
BAV21
SOD-123
30
R11
82R
0603
31
EC2
33uF/50V
CES-5X11
32
T1
EDR28
EDR28
33
U1
RT7302
SOP-8
34
D1
SF26
DO-15
35
R1
33.2R
1206
36
C1
220p/1kV
1206
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CONFIDENTIAL
BOM
Item
Location
Value
Type
37
EC1
220uF/63V
CES-10X25
38
L1
110uF
LR-T9
39
R4
200kohm
1206
40
C8
47.5kohm
1206
Total : 44 pcs
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CONFIDENTIAL
Transformer
top view
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CONFIDENTIAL
Power Component Stress Voltage
Test condition: 90Vac input / 60V,300mA output
Stead state
Location
Max rating (V)
Measure
De-rating
Q1
600
304
50.67%
D1
400
110
27.50%
Transient State
Location
Max rating (V)
Measure
De-rating
Q1
600
304
50.67%
D1
400
110
27.50%
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CONFIDENTIAL
Power Component Stress Voltage
Test condition: 264Vac input / 60V,300mA output
Stead state
Location
Max rating (V)
Measure
De-rating
Q1
600
568
94.67%
D1
400
227
56.75%
Transient State
Location
Max rating (V)
Measure
De-rating
Q1
600
572
95.33%
D1
400
230
57.50%
Suggestion: If change the Q1 from 600V to 650V. The de-rating
decrease to 87.38%(Stead state) and 88%(Transient state) .
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CONFIDENTIAL
Start up waveform
Vac_in = 90V
T_start up =760ms
Vac_in = 264V
T_start up =370ms
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CONFIDENTIAL
LED open protection
Vac_in = 90V
Ch2:Vout ; Ch3:Vzcd ; Ch4:Vdd
Vac_in = 264V
Ch2:Vout ; Ch3:Vzcd ; Ch4:Vdd
When LED open , the output keeps rising and causing the VZCD rising
accordingly. If Vzcd trigger the protected level(2.9V~3.3V), the IC latch down.
IC will be auto-restarted when the output is recovered.
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CONFIDENTIAL
LED Short protection
Vac_in = 90V
Ch2:Vout ; Ch3:Vgate ; Ch4:Vcs
Vac_in = 264V
Ch2:Vout ; Ch3:Vgate ; Ch4:Vcs
When LED short , the output level is 0V and the Vcs will rise to trigger the
protected function. IC will be auto-restarted when the output is recovered.
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CONFIDENTIAL
Harmonic(IEC61000-3-2)
110V input
Class C : Pass
Class D : Pass
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CONFIDENTIAL
Harmonic(IEC61000-3-2)
230V input
Class C : Pass
Class D : Pass
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CONFIDENTIAL
Conduction-EMI
230V-LPass
230V-N Pass
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CONFIDENTIAL
Conduction-EMI
110V-LPass
110V-N Pass
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CONFIDENTIAL
Radiation-EMI
230V-V Pass
230V-H Pass
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CONFIDENTIAL
Radiation-EMI
110V-V Pass
110V-H Pass
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