EVL170W-FTV STMicroelectronics, EVL170W-FTV Datasheet - Page 21

• Manufacturer Part Number: EVL170W-FTV
• Description: DEMO BOARD VIPER27 L6599A L6564
• Manufacturer: STMicroelectronics
• Series: VIPER™r

Specifications of EVL170W-FTV

• Main Purpose: Power Supply with PFC
• Outputs And Type: 2, Isolated
• Power - Output: 170W
• Voltage - Output: 24V, 12V, 5V
• Current - Output: 6A, 2A, 2A
• Voltage - Input: 90 ~ 264VAC
• Regulator Topology: Flyback
• Frequency - Switching: 130kHz
• Board Type: Fully Populated
• Utilized Ic / Part: Viper27LN, L6564, L6599A
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-11254

AN3329
Figure 37. Resonant stage waveforms at 115 V
CH1: HB voltage
CH3: HVG
Resonant stage
Some waveforms relevant to the resonant stage during steady-state operation are reported
in
voltage is around 75 kHz, in order to achieve a good trade-off between transformer losses
and size.
below resonance, therefore, the resonant current lags the voltage applied, as input
impedance of the resonant network is inductive. The current is negative during the rising
edge of half bridge voltage and positive during the falling-edge, providing, in both cases, the
energy to allow the node HB swinging. Because of the dead time, the MOSFETs are turned
on when resonant current is flowing through their body diodes and drain-source voltage is
almost zero. In
(#11) pins are observed. The switching frequency is programmed by the resistors connected
to the RFmin (#4) pin, which provides an accurate 2 V reference. The current flowing out
from the RFmin (#4) pin is internally mirrored and alternately charges and discharges the
capacitor connected to CF (#3). LINE (#7) pin voltage enables and disables the resonant
stage, preventing operation in capacitive mode.
In
operates slightly below resonance and therefore the output rectifiers are working in
discontinuous conduction mode, as energy transfer ends before each node HB voltage
swinging. Therefore, at primary side there are some short intervals where both diodes are
reverse-biased and the magnetizing inductance Lp, being no longer shunted by the output
capacitance reflected to the primary, becomes part of resonance. This corresponds to the
primary side current waveform to the portion circled in blue.
In the same image, it can be noted that the rectifiers PIV are operating within their voltage
rating and well below the BV, so ensuring long term reliability.
- 60 Hz, full load
Figure
Figure 39
37, 38, 39, 40, and 41. The switching frequency at full load and nominal input
Figure 37
the reverse voltages across secondary rectifiers are represented. The system
CH2: LVG
CH4: C39 current
Figure 38
shows the resonant ZVS operation. The converter operates slightly
voltages on the L6599A LINE (#7), RFmin (#4), CF (#3), and LVG
Doc ID 18376 Rev 1
Figure 38. Resonant stage waveforms at 115 V
CH1: LVG (pin #11)
CH3: RFmin (pin #4)
- 60 Hz, full load
CH4: LINE (pin #7)
CH2: CF (pin #3)
Functional check
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