delay

V+

t

,

(a)

(b)

t

V

+

t

(a)

(B)

t

LM3448

SNOSB51B – SEPTEMBER 2011 – REVISED NOVEMBER 2011

www.ti.com

Figure 17. Voltage Waveforms After Bridge Rectifier Without TRIAC Dimming

Figure 18(b) and Figure 18(a) show typical TRIAC dimmed voltage waveforms before and after the bridge

rectifier.

Figure 18. Voltage Waveforms After Bridge Rectifier With TRIAC Dimming

SENSING THE RECTIFIED TRIAC WAVEFORM

An external series pass regulator (R2, D1, and Q1) translates the rectified line voltage to a level where it can be

sensed by the BLDR pin on the LM3448 as shown in Figure 19.

10

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