EVALHVLED805
4.2 W off-line LED driver with primary side regulation
Data brief
Features
■
Input voltage range (VIN): 185 - 265 VAC
■
Main frequency (fL): 50 - 60 Hz
■
Maximum (rated) output power: 4.2 W
■
Output: IOUT = 350 mA ± 5%
– Over voltage = 12 V max
– Current ripple < 10% IOUT
■
Minimum switching frequency in
normal mode: 70 kHz
■
Target average efficiency
(from 1 to 3 LEDs) > 70 %
■
Maximum input power in no-load < 100 mW
Description
The EVALHVLED805 is a demonstration board
equipped with the new HVLED805 PWM current
mode LED driver and is designed for European
mains. It can control, with very good accuracy,
from 1 to 3 LEDs having a nominal current of 350
mA. The HVLED805 has integrated high voltage
startup and an 800 V power MOSFET. The high
MOSFET's breakdown voltage allows very robust
and reliable applications and reduces the size of
the snubber and the relative power dissipation. Its
accurate primary-current control eliminates the
need of the optocoupler which impacts the cost,
the compactness and the lifetime of the
application while still maintaining a very good
LED accuracy (below 5 %). Moreover, this
converter, specifically designed for quasiresonant (QR) flyback converters, enables very
low turn-on losses and EMI emissions.
February 2011
Doc ID 18457 Rev 1
For further information contact your local STMicroelectronics sales office.
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Electrical schematic
1
EVALHVLED805
Electrical schematic
Figure 1.
EVALHVLED805 electrical schematic
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Efficiency measurement
Figure 2.
Efficiency measurement with one, two or three LEDs
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The efficiency is always higher than 70 % when two or three LEDs are connected, whereas
it drops with one LED. The reason is that at low output voltage, the auxiliary voltage is not
able to supply the IC and the internal HV current generator self supplies the Vcc pin, thus
dissipating a power proportional to VIN.
The output current has been measured with two or three LEDs which obtain an accuracy
always below 5 %.
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EVALHVLED805
Figure 3.
Electrical schematic
Output current characteristics
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Figure 4.
Start up at 230 VAC, 3 LEDs
Figure 5.
Doc ID 18457 Rev 1
Start up at 230 VAC, 1LEDs
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Electrical schematic
EVALHVLED805
Figure 6.
Normal operation at 230 VAC,
3 LEDs
Figure 8.
Normal operation at 230 VAC: 1
LEDs
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Figure 7.
Doc ID 18457 Rev 1
Normal operation at 230 VAC,
2 LEDs
EVALHVLED805
Figure 9.
Electrical schematic
PCB top side and through hole components (not in scale)
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Figure 10. PCB: bottom side and SMD components (not in scale)
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Electrical schematic
Table 1.
Reference
Note:
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EVALHVLED805
Bill of material
Part
Description
Note
R1
22 Ω
1 W - Axial flame proof
R2
120 kΩ
R3
33 kΩ
R4
5.6 kΩ
R5
10 Ω
R6
10 kΩ
R7
3.3 kΩ
1% tolerance
R8
10 Ω
1% tolerance
R9
100 kΩ
C1, C2
2.2 µF
400 V electrolytic
C3
1 nF
500 V - XR7
C4
2.2 uF
35 V electrolytic
C5
1 nF
25 V
C6
470 nF
25 V
C7
4.7 nF
25 V
C8, C9
B41889A3108M
100 µF
16V electrolytic Rubycon ZLH
C10
Y1- Capacitor
2.2 nF
230V
D1
STTH1L06A
Ultra-fast high voltage diode
STMicroelectronics
D2
LL4148
Small signal diode
D3
STPS1H100A
Power schottky diode
STMicroelectronics
L1
B78108S1474J
470µH
axial inductor Epcos
BR
MB6S RC
Input bridge rectifier
TF
1921.0013 Rev.2
Flyback transformer
Magnetica
IC
HVLED805
Primary switching regulator
STMicroelectronics
If not otherwise specified, all resistors are 5%, ¼ W
Doc ID 18457 Rev 1
EVALHVLED805
Electrical schematic
Table 2.
Transformer characteristics
Manufacturer
Magnetica
Part number
1921.0013 Rev. 2
Core
E13 – N87 (or equivalent)
Primary inductance
2.6mH ± 15%
Air gap
˜ 70 µm
Leakage inductance
1.42% nom
Primary to secondary turn ratio
7.68 ± 5% (123 : 14)
Primary to auxiliary turn ratio
5.59 ± 5% (123 : 19)
Primary saturation current
0.21AP max (BSAT=0.35 T)
Insulation primary-secondary
4 kV
Figure 11. Transformer electrical scheme and dimensions
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Revision history
2
EVALHVLED805
Revision history
Table 3.
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Document revision history
Date
Revision
09-Feb-2011
1
Changes
First release
Doc ID 18457 Rev 1
EVALHVLED805
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