EVL170W-FTV STMicroelectronics, EVL170W-FTV Datasheet - Page 17

• 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 27. Standby supply dynamic load at
CH1: FB (pin #4)
CH3: +5 V standby
In
short-circuit is detected, an internal current source charges the device internal circuitry and
stops the auxiliary converter operation until the V
(4.5 V). At that time the internal HV current source is activated and charges the V
capacitor until it reaches the V
soft-start cycle. Hiccup cycles are repeated as long as the short-circuit condition lasts.
Viper27LN is resumed back to normal operation only when the short-circuit condition is
removed.
Figure 27
has been tested in the most critical situation, the transition from full load to no load and vice
versa. In fact, when a flyback converter is operating at full load, typically the self supply
voltage V
decreased or removed, V
no load operation, at high mains the burst pulses have a low repetition rate due to the almost
negligible residual load. In this condition the V
causing the auto-restart cycles activation by the controller and consequent reset by the
microprocessor powered by the 5 V standby. As can be seen in
transitions are clean and there is no output voltage or Vcc dip.
115 Vac - 60 Hz - PFC off
Figure 26
DD
and
spike is quite high, due to the effect of the leakage inductance. Once the load is
details of Viper27LN operation at short detection is captured; once an output
28
CH2: V
CH4: 5 V stby current
show the load regulation for the 5 V standby output. The standby supply
DD
DD
(pin #2)
tends to reduce. Since the circuit works in burst-mode during
Doc ID 18376 Rev 1
DDon
threshold, then the Viper27LN restarts switching via a
Figure 28. Standby supply dynamic load at
CH1: FB (pin #4)
CH3: 5 V standby
DD
DD
might drop below V
voltage drops down to V
115 Vac - 60 Hz - PFC on
Figure 27
CH4: 5 V stby current
CH2: V
DD_RESTART
Functional check
DD
and 28, both
DD_RESTART
(pin #2)
(4.5 V),
DD
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