SSL8516T datasheet(12/33 Pages) NXP

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SSL8516T

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Product data sheet

Rev. 1 — 5 May 2014

12 of 33

NXP Semiconductors

SSL8516T

Greenchip PFC and flyback controller

When VVOSENSE exceeds the VOVP(VOSENSE) level, switching of the PFC circuit is

prevented. Switching of the PFC restarts when the VOSENSE pin voltage drops below the

VOVP(VOSENSE) level again.

OVP is also triggered when the resistor between the VOSENSE pin and ground is open.

7.2.11 PFC open-loop protection (VOSENSE pin)

The PFC circuit does not start switching until the VVOSENSE pin is greater than the

Vth(start)(VOSENSE) level. This feature protects the application from open-loop and

VOSENSE short-circuit situations.

7.2.12 Driver (PFCDRIVER pin)

The driver circuit to the gate of the power MOSFET includes a current sourcing capability

of 500 mA at 2 V on the PFCDRIVER pin. It also includes a current sink capability of 1.2 A

at 10 V on the PFCDRIVER pin. These capabilities ensure fast switch-on and switch-off of

the power MOSFET for efficient operation.

7.3 Flyback controller

The SSL8516T includes a controller for a flyback converter. The flyback converter

operates in quasi-resonant or discontinuous conduction mode with valley switching. The

auxiliary winding of the flyback transformer provides demagnetization detection and

powers the IC after start-up.

7.3.1 Multimode operation

The SSL8516T flyback controller can operate in several modes; see Figure 7.

At high output power the converter switches to quasi-resonant mode. The next converter

stroke starts after demagnetization of the transformer and detection of the valley. In

quasi-resonant mode switching losses are minimized. This minimization is achieved by

the converter only switching on when the voltage across the external MOSFET is at its

minimum (see Section 7.3.2).

Fig 7.

Multimode operation flyback

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