TLE6282 H-Bridge And Half Bridge Driver IC

The converter shown uses a member of the TinySwitch-III family (U2, a TNY279PN) to provide up to 1. 8 A of load current to six, high-intensity, Luxeon LEDs (the LXHL series). The output voltage is slightly below the forward voltage drop of the LEDs Therefore, when the LEDs are connected to the supply, it operates in constant c

urrent (CC) mode. If the LEDs are discon- nected from the supply, Zener Diode VR1 provides voltage feedback, which regulates the output voltage at about 13. 5 VDC. A 100 m © resistor (R11) senses the output current and an Opamp (U1) drives the Optocoupler (U3), which provides feedback to U2. The TinySwitch-III family of devices regulate by disabling or skipping MOSFET switching cycles. As the load current reaches the current limit set-point threshold, U1 drives U3 on. The photo- Transistor in U3 pulls current out of the EN/UV pin of U2, causing it to skip switching cycles. Once the output current drops below the current limit set-point threshold, U1 stops driving U3, which stops pulling current out of the EN/UV pin of U2, and switching cycles are enabled again. The TL431 (U4) provides a reference for U1 to compare against the voltage drop across R11. The output Diode (D9) is located in the lower leg of the transformer (T1) secondary winding to reduce EMI noise generation. An RCD clamp (R16, C4 and D13) protects the drain node of the MOSFET from the‚ flyback voltage spike. The Valley Fill circuit (D5, D6, D7, C15, C16 and R15) limits the values of the third and fth harmonics of the line frequency current, which enables this supply to meet the requirements for Total Harmonic Distortion (THD) speci ed in IEC61000-3-2. The frequency jittering function in U2, a shield winding in T1 and a Y class capacitor (C8) across T1 reduce...

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