SSL8516BT datasheet(29/35 Pages) PHILIPS

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SSL8516BT

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Product data sheet

Rev. 1 — 26 May 2015

29 of 35

NXP Semiconductors

SSL8516BT

Greenchip PFC and flyback controller

11. Application information

An LED driver with the SSL8516BT consists of a PFC circuit and a flyback converter (see

Figure 17).

Capacitor CVCC buffers the IC supply voltage. The IC supply is charged from the high

voltage rectified mains during start-up and the auxiliary winding of the flyback converter

during operation. Sense resistors RSENSE1 and RSENSE2 convert the current through the

MOSFETs S1 and S2 into a voltage on the PFCSENSE and FBSENSE pins. The RSENSE1

and RSENSE2 values define the maximum primary peak current in MOSFETs S1 and S2.

In the example, the LATCH pin is connected to a Negative Temperature Coefficient (NTC)

resistor. The protection is activated when the resistance drops below the value as

calculated in Equation 8:

(8)

Capacitor CTIMEOUT is connected to the FBCTRL pin. RLOOP ensures that the time-out

capacitor does not interfere with the flyback regulation control loop.

RS1 and RS2 prevent that the soft-start capacitors CSS1 and CSS2 are charged during

normal operation due to negative voltage spikes across the sense resistors.

Resistor RAUX1 protects the IC from damage during lightning events.

RS3 and RCOMP can be used to lower the PFC on/off power level. The minimum and

maximum peak current ratio increase. So, the PFC switch-on and switch-off power level

decreases.

RDRV1 and RDRV2 prevent that the internal MOSET drivers are damaged due to, for

example, power MOSFET avalanche.

Depending on the drain voltage maximum rating of MOSFET S2, the HV pin of the IC can

either be connected to the center tap of the flyback transformer or to the drain of MOSFET

S2.

prot LATCH



OLATCH



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16.2 k



SSL8516BT датащи(PDF) 29 Page - NXP Semiconductors