Ultracompact LCD Backlight


Posted on Nov 29, 2012

Figure 9 is a detailed schematic of Figure 8s concept. The resonance loop is comprised of Q4 and the CMOS inverter based oscillator. The amplitude loop centers around the LT1375 switching regulator. Figure 10 shows waveforms. Traces A and B are Q2 and Q1 gate drives, respectively. Resultant Q1 and Q2 drain responses are traces C and D.



The LT1375 step-down switching regulator, responding to the rectified and averaged lamp current, closes the amplitude loop by driving the L1-L2 junction (trace E). The 4.7mF capacitor at the VC pin stabilizes the loop.8 Note that no filtering is used




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