EVL170W-FTV STMicroelectronics, EVL170W-FTV Datasheet - Page 23

• 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 42. 12 V - 2 A; 24 V 0 ÷ 6 A transition at
CH1: +24 V O/P voltage
Dynamic load operation and output voltage regulation
Figure 42
the resonant stage outputs. The waveforms have been captured applying a load transient
from 0 to full load to one output while the other is delivering full load. The period of load
steps has been selected very long (1 s), to allow the output voltage to reach the steady-state
condition and output voltage waveforms have been captured using the DC coupling of the
scope to avoid waveform distortions caused by the AC coupling. A suitable offset has been
also added to waveforms in order to get the maximum resolution.
Figure 42
the 12 V output is delivering the 2 A rated load. It can be noted that the 24 V output voltage
has a tight variation, because even considering the spikes at the current edges, it is within
+/- 4 %.
In the same way, in
dynamic load on the 12 V output, while the 24 V output is delivering the 6 A rated load. It can
be noted that the 12 V output has a very tight variation - within +/- 3 %.
Cross regulation
Figure 44
300 Hz load step frequency on one output, with the other delivering the rated load.
Figure 44
output. Load is varying from minimum to maximum and vice versa, as typically happens in a
flat-TV because of backlight dimming and audio power amplifiers. Even in this condition, the
24 V output has a maximum deviation of ± 4 %, mainly due to the series filter inductor L4.
The 12 V output variation due to the dynamic load on 24 V (cross-regulation) is ± 2 %,
therefore very tight and suitable to power properly the internal logic of the LCD panel.
In
the 12 V load is changing from 1 to 2 A, as may happen when powering the LCD panel, and
the variation of 24 V at rated load is measured. It can be noted in the image that the 12 V
output has a deviation less than ± 1.2 %, while the 24 V output variation due to the dynamic
load on 12 V (cross-regulation) is ± 0.5 %.
115 Vac - 60 Hz
Figure 45
and
reports the output voltage regulation with a dynamic load on 24 V output while
and
shows the simulation of the backlight and audio amplifier connected to the 24 V
cross regulation between the 12 V and 24 V has been measured. In this image
CH2: +24 V O/P current
43
45
show the output voltage regulation in the case of load transients on both
show the output voltage cross regulation similar to previous tests but at
Figure 43
it is possible to see the output voltage regulation with a
Doc ID 18376 Rev 1
Figure 43. 24 V - 6 A; 12 V 0 ÷ 2 A transition at
CH1: +12 V O/P voltage CH2: +12 V O/P current
115 Vac - 60 Hz
Functional check
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