STMicroelectronics EVALHVLED815W10 and EVALHVLED815W15 Evaluation Board for the Offline LED Driver with Primary-Sensing and High Power Fact EVALHVLED815W10 データシート
製品コード
EVALHVLED815W10
Device description
HVLED815PF
14/34
DocID023409 Rev 5
4 Device
description
The HVLED815PF device is a high voltage primary switcher intended for operating directly
from the rectified mains with minimum external parts to provide high power factor (> 0.90)
and an efficient, compact and cost effective solution for LED driving. It combines a high-
performance low voltage PWM controller chip and an 800 V, avalanche rugged Power
MOSFET, in the same package.
from the rectified mains with minimum external parts to provide high power factor (> 0.90)
and an efficient, compact and cost effective solution for LED driving. It combines a high-
performance low voltage PWM controller chip and an 800 V, avalanche rugged Power
MOSFET, in the same package.
The PWM is a current mode controller IC specifically designed for ZVS (“Zero Voltage
Switching”) flyback LED drivers, with constant output current (CC) regulation using primary
sensing feedback (PSR). This eliminates the need for the optocoupler, the secondary
voltage reference, as well as the current sense on the secondary side, while still maintaining
a good LED current accuracy. Moreover, it guarantees a safe operation when short-circuit of
one or more LEDs occurs.
Switching”) flyback LED drivers, with constant output current (CC) regulation using primary
sensing feedback (PSR). This eliminates the need for the optocoupler, the secondary
voltage reference, as well as the current sense on the secondary side, while still maintaining
a good LED current accuracy. Moreover, it guarantees a safe operation when short-circuit of
one or more LEDs occurs.
The device can also provide a constant output voltage regulation (CV): it allows the
application to be able to work safely when the LED string opens due to a failure.
application to be able to work safely when the LED string opens due to a failure.
In addition, the device offers the shorted secondary rectifier (i.e. LED string shorted due to
a failure) or transformer saturation detection.
a failure) or transformer saturation detection.
Quasi-resonant operation is achieved by means of a transformer demagnetization sensing
input that triggers MOSFET turn-on. This input serves also as both output voltage monitor,
to perform CV regulation, and input voltage monitor, to achieve mains-independent CC
regulation (line voltage feedforward).
input that triggers MOSFET turn-on. This input serves also as both output voltage monitor,
to perform CV regulation, and input voltage monitor, to achieve mains-independent CC
regulation (line voltage feedforward).
The maximum switching frequency is top limited below 166 kHz, so that at medium-light
load a special function automatically lowers the operating frequency while still maintaining
the operation as close to ZVS as possible. At very light load, the device enters a controlled
burst mode operation that, along with the built-in high voltage startup circuit and the low
operating current of the device, helps minimize the residual input consumption.
load a special function automatically lowers the operating frequency while still maintaining
the operation as close to ZVS as possible. At very light load, the device enters a controlled
burst mode operation that, along with the built-in high voltage startup circuit and the low
operating current of the device, helps minimize the residual input consumption.
Although an auxiliary winding is required in the transformer to correctly perform CV/CC
regulation, the chip is able to power itself directly from the rectified mains. This is useful
especially during CC regulation, where the flyback voltage generated by the winding drops.
regulation, the chip is able to power itself directly from the rectified mains. This is useful
especially during CC regulation, where the flyback voltage generated by the winding drops.
4.1 Application
information
The device is an off-line LED driver with all-primary sensing, based on quasi-resonant
flyback topology, with high power factor capability. In particular, using different application
schematic the device is able to provide a compact, efficient and cost-effective LED driver
solution with high power factor (PF > 0.9 - see application schematic in
flyback topology, with high power factor capability. In particular, using different application
schematic the device is able to provide a compact, efficient and cost-effective LED driver
solution with high power factor (PF > 0.9 - see application schematic in
or with standard power factor (PF > 0.5/0.6 - see application schematic in
), based on the specific application requirements.
Referring to the application schematic in
, the IC modulates the input current
according to the input voltage providing the high power factor capability (PF > 0.9) keeping
a good line regulation. This application schematic is intended for a single range input
voltage.
a good line regulation. This application schematic is intended for a single range input
voltage.
For wide range application a different reference schematic can be used; refer to AN4346
application note for further details.
application note for further details.