EVL6566B-65W STMicroelectronics, EVL6566B-65W Datasheet - Page 2

• Manufacturer Part Number: EVL6566B-65W
• Description: BOARD EVAL FOR L6566B
• Manufacturer: STMicroelectronics

Specifications of EVL6566B-65W

• Main Purpose: AC/DC, Primary Side
• Outputs And Type: 1, Isolated
• Power - Output: 65W
• Voltage - Output: 12V
• Current - Output: 5.4A
• Voltage - Input: 90 ~ 265VAC
• Regulator Topology: Flyback
• Frequency - Switching: 80kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6566B
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6452

APPLICATION NOTE
Main characteristics and circuit description
The topology of this converter is the classical Flyback working in continuous and discontinuous
conduction mode at fixed frequency.
The controller, the new L6566B, is an extremely versatile current mode primary controller ICs. The
nominal switching frequency, 80 KHz, has been chosen to get a compromise between the
transformer size and the converter efficiency. The input EMI filter is a classical Pi-filter, 2-cells for
differential and common mode noise filtering. A NTC limits the inrush current produced by the
capacitor charging at plug-in. The MOSFET is a standard and inexpensive 600V-0.75Ωmax, TO-
220FP, needing a heat sink. The transformer is a layer type, using a standard ferrite type EER28L.
The reflected voltage is 90 V, providing enough room for the leakage inductance voltage spike with
still margin for reliability of the MOSFET. The network D3, R11A, R11B, R11C and C11 clamps the
peak of the leakage inductance voltage spike.
At power on, the L6566B has an internal high-voltage current source sourcing a current from the
DC bus and charging the capacitors C2 and C3 connected to the Vcc pin. Once the turn-on
threshold is reached, the HV current source is turned-off. This allows saving power dissipation
during normal operation and provides very good circuit efficiency during standby. The divider R4,
R10, R45 and R46 senses the input voltage and it is dedicated to the Brownout and Voltage feed-
forward pins. The AC_OK pin (#16) is dedicated to the brownout protection. When the voltage on
this pin is below the internal threshold (0.45V typ.) the IC is disabled. The VFF pin (pin#15), is
dedicated to limit the maximum power deliverable according to the input voltage of the converter.
As previously mentioned, the control system is Current Mode, so the current flowing in the
transformer primary winding is sensed by R7B, R7C and R7D then it is fed into the CS (pin #7).
For over voltage protection (OVP), the transformer auxiliary winding is connected to ZCD (pin #11)
via the R3 and R9 divider. In case of feedback network failures or open loop operation, if the
voltage on ZCD pin rises over its threshold the L6566B is latched. After OVP detection and the
following latch, the controller operation can be resumed by disconnecting the mains plug.
The switching frequency is programmed by OSC (pin #13) connected to the resistor R18.
Furthermore the L6566B has the Soft Start (pin #14), Disable (pin #8) and 5 Volt Reference
voltage VREF (pin #10) available.
The output rectifier is a dual common-cathode Schottky diode, Q201. A snubber, made up of
R19A, R19B and C12, damps the oscillation produced by the diode Q201. A small LC filter has
been added on the output in order to reduce the high frequency ripple.
The output regulation makes use of a dedicated control IC, the TSM1014, embedding a refernce
and an error ampliifer. The output signal of the error amplifier drives the optocoupler OPTO4
transferring the information to primary side with the required insulation of the secondary side.
Circuit description
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UNIVERSAL INPUT MAINS RANGE:
OUTPUT VOLTAGE:
MAINS HARMONICS:
ST-BY MAINS CONSUMPTION:
OVERALL EFFICIENCY:
EMI:
SAFETY:
DIMENSIONS:
PCB:
90÷264Vac - Frequency 45 ÷ 65Hz
12V@5.42A continuous operation
Acc. to EN61000-3-2 Class-D
TYP. 0.2 W @265Vac
TYP. 83 % @ 230Vac
According to EN55022-Class-B
According to EN60950
51 x 109.5mm
Double layer
mixed PTH/SMD technology
- 25mm maximum height
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