S-8533 Series
www.sii-ic.com
STEP-DOWN, SYNCHRONOUS PWM CONTROL
SWITCHING REGULATOR CONTROLLER
© Seiko Instruments Inc., 2002-2010 Rev.3.0_00
Seiko Instruments Inc. 1
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 (C
SS
)
• Shutdown function
• Lead-free, Sn 100%, halogen-free
*1
*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
