S-8533 Series STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER www.sii-ic.com SII Semiconductor Corporation, 2002-2010 Rev.3.0 01 The S-8533 Series is a synchronous PWM control CMOS step-down switching regulator controller that includes a reference voltage source, synchronous circuit, oscillation circuit, error amplifier, phase compensation circuit, and PWM controller. An efficient step-down switching regulator can be realized simply by adding external P-channel and N-channel power MOS FETs, one coil, and three capacitors. Since the oscillation frequency is a high 300 kHz, the S-8533 can be used to configure a high efficiency step-down switching regulator capable of driving high output current using small external parts and a 3 to 10% increase in efficiency is obtained compared to conventional step-down switching regulators. The 8-Pin TSSOP package and high oscillation frequency make the S-8533 ideal as the main power supply for portable devices. Features Synchronous rectification system realizing high efficiency (typ. 94%) Use at maximum duty ratio = 100% and use of a battery up to maximum life is possible by using P-channel and N- channel power MOS FETs externally. Oscillation frequency : 300 kHz typ. Input voltage : 2.7 to 16.0 V Output voltage : 1.25 V 1.3 to 6.0 V, selectable in 0.1 V steps Output voltage accuracy : 2.0% Soft-start function set by an external capacitor (CSS) Shutdown function *1 Lead-free, Sn 100%, halogen-free *1. Refer to Product Name Structure for details. Applications Constant voltage power supply for hard disks and DVD drivers Power supplies for portable devices, such as digital cameras, PDAs, electronic organizers, and cellular phones Main or sub power supply for notebook PCs and peripherals Constant voltage power supply for cameras, video equipment, and communication equipment Package 8-Pin TSSOP 1 STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER S-8533 Series Rev.3.0 01 Block Diagram L Tr Oscillation VIN circuit VOUT + PDRV C PWM control circuit OUT P.N feed-through NDRV prevention circuit + + Tr V C IN IN Reference voltage VSS source with soft start C CSS SS ON / OFF Remark All the diodes in the figure are parasitic diodes. Figure 1 2