DS-16,Highly Efficiency Very Low Output Voltage Buck Converter for PoweringLow Voltage Graphics ASICs in Mobile Phones, 4.2V To 3.2V Input WithLogic Selectable 1.0V and 1.5V Regulated Output

Category: Logic
Manufacture: Sipex Corporation
Datasheet: Download this application note

SP6656 Converts Li-Io Battery to Low Output Voltages
March 22, 2006 Brian Kennedy (bkennedy@sipex.com)
Part Number: SP6656 Application Description: Graphics ASICs in Mobile Phones Electrical Requirements: Input Voltage Output Voltage Output Current 3.0V 4.2V 1.1V and 1.5V (logic selectable) 400mA
Circuit Description: The SP6656 is designed to provide dynamic adjustment of its output voltage in response to a logic control signal. The circuit in Figure 5 provides two levels of output voltages: 1.1V and 1.5V. This can be used in portable applications by a graphics IC or an ASIC in order to improve its power consumption. Understand that, by mode, the voltage is reduced to 1.1V in order to provide lower power dissipation. When full performance is required, the SP6656 is commanded to increase its voltage to the pre-set level 1.5V for this schematic. Circuit performance, such as efficiency and load regulation is shown in Figures 1 through 4. Low quiescent current of the SP6656 is ensuring very high efficiency even at 100uA load currents!
SP6656 Converting to low Output Voltages Page 1 of 4
Copyright 2006 Sipex Corporation
Efficiency at 1.5Vout
90 80 70 60 50 0.10 V in=3.3V V in=4.2V
Figure 1. Efficiency Graph for 1.5V Output Voltage
Efficiency at 1.1Vout
100 90 80 70 60 50 0.10 V in=3.3 V V in=4.2V
Figure 2. Efficiency Graph for 1.1V Output Voltage
SP6656 Converting to low Output Voltages Page 2 of 4
Copyright 2006 Sipex Corporation

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