5_V_from_two_to_thre_cells_with_low_noise

Published:2009/7/24 23:24:00 Author:Jessie | From:SeekIC

Figure 8－90 shows a MAX751 connected to provide a 5-V output. with a 2-V to 5-V input range, but with low nolse. This circuit provides a fixed－frequency PWMalternative to the pulse-skipping control scheme usually found in low-voltageswitching-regulator ICs. (The noise generated by switching regulators is a major problem in many portable products such as cellular phones and medicalinstruments,) The trade-offs for low-noise operation are increased quiescent supply current and lower efficiency for light loads．The quiescent current with a VIN of 3 V is 1.2 mA, with a maximum load current of 100 mA (with VIN＝2.7 V). The circuit has a shutdown current of 30 μA and a fixed oscillator frequency of 170kHz，The no-load start-up is 1.2 V． Figure 8-91 shows the efficiency curves. MAXIMBATTERY MANAGEMENT CIRCUIT COLLECTION 1994 P. 13．



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