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12V/5A AC Adapter Demoboard L6565 – Quasi-Resonant Controller Demoboard Performance.

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Presentation on theme: "12V/5A AC Adapter Demoboard L6565 – Quasi-Resonant Controller Demoboard Performance."— Presentation transcript:

1 12V/5A AC Adapter Demoboard L6565 – Quasi-Resonant Controller Demoboard Performance

2 L6565 – Features Overview

3 L6565 – Block Diagram Zero Current Detection Once detect the negative going edge demag signal, it triggers the MOSFET turn-on. Output Drive Capability 400mApk Error Amplifier feedback input, FB regulate at 2.5V Current sense input, signal exceeds 2V will make the controller running into hiccup mode. Input of the comparator, the outcoming signal depending on the comp and the VFF pin UVLO, Vcc turn-on 13.5V and turn-off 9.5V Output of the current comparator block, It will be active when the current signal exceeds 2V

4 L6565 – Internal Supply Block Once the Vcc reaches the startup voltage, the controller begins to operate

5 L6565 – Zero Current Detection Once the demag pin goes down below 1.6V, the EXT MOSFET will be switched on.To ensure high noise immunity, the triggering block must be armed first: prior to falling below 1.6V, the voltage on pin 5 must experience a positive-going edge exceeding 2.1 V.

6 Zero Current Detect Operation

7 Major Parasitic Elements in Flyback Converter where Cd is the total capacitance of the drain node Llk is the leakage inductance of the transformer Lm is the magnetizing inductance of the transformer

8 V DS Waveform The first valley occurs at T = Tv, where Tv will be as the following For zero voltage condition, it implies that where

9 QR  Timing and Power Relationship MOSFET ON time: MOSFET OFF time: Switching Frequency: Input Power: The switching frequency related to input power: where

10 L6565 – Power Compensation, high line and low line

11 Switching Frequency vs. Operating Condition In order to deliver the full loading power at minimum input voltage, the inductance should not exceed the following value:

12 Switching Frequency Foldback The Tblank function is the function of the Vcomp output

13 L6565 – Syn-Rect Demoboard Circuit QR mode is the perfect topology for syn-rect because secondary current flow stops before primary MOSFET switches on!

14 Low Startup Circuit This part is for startup purpose use. The power loss dissipation is much reduced compared with the traditional lossy R-C startup circuit. The charge current pump into the Vcc capacitor at a rate of.

15 Isolation Gate Drive Transformer L202 – isolated gate drive transformer The gate drive voltage is converted from the secondary current. When the secondary current is large enough, it turns on the Q203, then an output voltage is directly going into the totem pole input and drive the secondary MOSFET. When the secondary current drops to zero, there will be no driving voltage from the isolated gate drive transformer, and Q203 turn-off and the MOSFET will not turn on. Isolated gate drive transformer Secondary current Make use of syn-rect approach, efficiency improves significantly!

16 Operating Waveforms Primary current Vdrain Vin = 100Vac, Vo=12.3V and Io=5A Primary current Vdrain Vin = 240Vac, Vo=12.3V and Io=5A

17 Operating Waveforms Vin = 240Vac, Output Short Circuit Primary current Vdrain Vin = 100Vac, Vo=12.3V and Io=5A Primary current Vdrain

18 Transformer Design (I)

19 Transformer Design (II) In Quasi-Resonant mode control, the current always starting from zero of every switching cycle. 

20 Syn-Rect Demoboard Transformer Np: 520uH

21 Syn-Rect Demoboard Full Load Efficiency

22 No Load Input Power

23 Demoboard BOM ItemReferencePartDescription 1 Assembly Dwg. 2 Schemaitc 3 PC BoardPC Board,1-Layers,60mm x118mm 4F1013A/250Vfuse 5RT9D-207 6RVG471varistor 7R10115ohmresistor 8R102100K3W resistor 9R10410ohmresistor 10R10515ohmresistor 11R1063Mresistor 12R10716Kresistor 13R108A,R108B510Kresistor 14R11047Kresistor 15R201,R2031Kresistor 16R202100ohmresistor 17R204470ohmresistor

24 Demoboard BOM 18R2075.1Kresistor 19R20820Kresistor 20RS ohm3W resistor 21CX UF/275VX2 cap 22C1011nF/1KVcapacitor 23C102150U/400VEcap 24C103220U/25Vcapacitor 25C10410nF/50Vcapacitor 26C105,C2051nF/50Vcapacitor 27C10656nF/400Vcapacitor 28C201,C202,C uF/25VEcap 29C204470U/25VEcap 30C2066.8nF/63Vcapacitor 31C207100nF/50Vcapacitor 32CY222U/275VY1 cap 33BR101KBU406bridge rectifier 34D101,D102,D2011N4148diode

25 Demoboard BOM 35D103clamper diodediode 36D104FR107diode 37Q101STP10NK60ZMOSFET 38Q201STP1806MOSFET 39Q202,Q2032N3904transistor 40Q2042N3906transistor 41Q205TL431voltage reference 42L101 共模 common mode choke 43L102 共模 common mode choke 44L201 差模 differential mode choke 45L202 感应磁环 gate drive transformer 46OPTK817P6opto-coupler 47IC101L6565SO8 48TR1Transformertransformer


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