SSL2103

All information provided in this document is subject to legal disclaimers.

© NXP B.V. 2010. All rights reserved.

Product data sheet

Rev. 2 — 25 November 2010

8 of 21

NXP Semiconductors

SSL2103

SMPS controller IC for dimmable LED lighting

Figure 7 shows a typical curve for a reflected output voltage N at an output voltage of

80 V. This voltage is the output voltage transferred to the primary side of the transformer

with the factor N (determined by the turns ratio of the transformer). It shows that the

system switches exactly at minimum drain voltage for ringing frequencies of 480 kHz, thus

reducing the switch-on losses to a minimum. At 130 kHz, the next primary stroke is started

at 33

 before the valley. The switch-on losses are still reduced significantly.

A: Start of new cycle with valley switching.

B: Start of new cycle in a classic PWM system.

Fig 6.

Signals for valley switching, flyback configuration

Fig 7.

Typical phase of drain ringing at switch-on (at N

 V

014aab110

drain

valley

secondary

ringing

secondary

stroke

primary

stroke

secondary

stroke

RC

oscillator

regulation level

A

B

0

200

400

800

f (kHz)

phase

(

°)

40

20

−20

−40

0

014aab111

600