Техническая Спецификация для STMicroelectronics 400 W FOT-controlled PFC pre-regulator with the L6563S EVL6563S-400W EVL6563S-400W
Модели
EVL6563S-400W
AN2994
Main characteristics and circuit description
Doc ID 15796 Rev 2
5/38
1
Main characteristics and circuit description
The EVL6563S-400W demonstration board has the following characteristics.
●
Line voltage range: 90 to 265 Vac
●
Minimum line frequency (f
L
): 47 Hz
●
Regulated output voltage: 400 V
●
Rated output power: 400 W
●
Maximum 2f
L
output voltage ripple: 10 V pk-pk
●
Hold-up time: 22 ms (V
DROP
after hold-up time: 300 V)
●
Maximum switching frequency: 85 kHz (Vin = 90 Vac, Pout = 400 W)
●
Minimum estimated efficiency: 90% (Vin = 90 Vac, Pout = 400 W)
●
Maximum ambient temperature: 50 °C
●
EMI: in accordance with EN55022 Class-B
●
PCB type and size: single side, 70 µm, CEM-1, 148.5 x 132 mm
●
Low profile design: 35 mm component maximum height
The demonstration board implements a power factor correction (PFC) pre-regulator
delivering 400 W of continuous power on a regulated 400 V rail from a wide-range mains
voltage, and providing for the reduction of the mains harmonics, thus complying with the
European norm EN61000-3-2 and the Japanese norm JEITA-MITI. This rail will be the input
for the cascaded isolated DC-DC converter that will provide the output voltages required by
the load.
delivering 400 W of continuous power on a regulated 400 V rail from a wide-range mains
voltage, and providing for the reduction of the mains harmonics, thus complying with the
European norm EN61000-3-2 and the Japanese norm JEITA-MITI. This rail will be the input
for the cascaded isolated DC-DC converter that will provide the output voltages required by
the load.
The board is equipped with enough heat sinking to allow full-load operation in still air. With
an appropriate airflow and without any change in the circuit, the demonstration board can
easily deliver up to 450 W.
an appropriate airflow and without any change in the circuit, the demonstration board can
easily deliver up to 450 W.
The controller is the L6563S (U1), integrating all the functions needed to control the PFC
stage and to interface with the downstream converter. The L6563S controller chip is
designed for transition-mode (TM) operation, where the boost inductor works next to the
boundary between continuous (CCM) and discontinuous conduction mode (DCM). However,
with a slightly different usage, the chip can operate so that the boost inductor works in CCM,
hence surpassing the limitations of TM operation in terms of power handling capability. The
gate-drive capability of the L6563S is also adequate to drive the MOSFETs used at higher
power levels. This approach, which couples the simplicity and cost-effectiveness of TM
operation with the high-current capability of CCM operation, is the fixed off time (FOT)
control. The control modulates the ON time of the power switch, while its OFF time is kept
constant. More precisely, the line-modulated FOT (LM FOT) is used, where the OFF time of
the power switch is not rigorously constant but is modulated by the instantaneous mains
voltage. Refer to [2] for a detailed description of this technique.
stage and to interface with the downstream converter. The L6563S controller chip is
designed for transition-mode (TM) operation, where the boost inductor works next to the
boundary between continuous (CCM) and discontinuous conduction mode (DCM). However,
with a slightly different usage, the chip can operate so that the boost inductor works in CCM,
hence surpassing the limitations of TM operation in terms of power handling capability. The
gate-drive capability of the L6563S is also adequate to drive the MOSFETs used at higher
power levels. This approach, which couples the simplicity and cost-effectiveness of TM
operation with the high-current capability of CCM operation, is the fixed off time (FOT)
control. The control modulates the ON time of the power switch, while its OFF time is kept
constant. More precisely, the line-modulated FOT (LM FOT) is used, where the OFF time of
the power switch is not rigorously constant but is modulated by the instantaneous mains
voltage. Refer to [2] for a detailed description of this technique.
The power stage of the PFC is a conventional boost converter, connected to the output of
the rectifier bridge D2. It includes the coil L4, the diode D3 and the capacitors C6 and C7.
The boost switch is represented by the power MOSFETs Q1 and Q2. The NTC R2 limits the
inrush current at switch on. It has been connected to the DC rail, in series to the output
electrolytic capacitor, in order to improve the efficiency during low line operation.
Additionally, the splitting into two of the output capacitors (C6 and C7) means that the AC
current is mainly managed by the film capacitor C7, making the electrolytic cheaper
because it only has to bear the DC part.
the rectifier bridge D2. It includes the coil L4, the diode D3 and the capacitors C6 and C7.
The boost switch is represented by the power MOSFETs Q1 and Q2. The NTC R2 limits the
inrush current at switch on. It has been connected to the DC rail, in series to the output
electrolytic capacitor, in order to improve the efficiency during low line operation.
Additionally, the splitting into two of the output capacitors (C6 and C7) means that the AC
current is mainly managed by the film capacitor C7, making the electrolytic cheaper
because it only has to bear the DC part.