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S-8541

Seiko Instruments
Part Number S-8541
Manufacturer Seiko Instruments
Description (S-8540 / S-8541) 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Published Aug 28, 2009
Detailed Description Rev.3.2_00 www.DataSheet4U.com STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER S-8...
Datasheet PDF File S-8541 PDF File

S-8541
S-8541


Overview
Rev.
3.
2_00 www.
DataSheet4U.
com STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER S-8540/8541 Series The S-8540/8541 Series is a family of CMOS stepdown switching regulator controllers with PWM control (S-8540 Series) and PWM/PFM switchover control (S8541 Series).
These devices consist of a reference voltage source, oscillation circuit, an error amplifier, phase compensation circuit, PWM control circuit, current limit circuit.
A high efficiency and large current switching regulator is realized with the help of small external components due to the high oscillation frequency, 300 kHz and 600 kHz.
The S-8540 Series provides low-ripple voltage, high efficiency, and excellent transient characteristics which come from the PMW control circuit capable of varying the duty ratio linearly from 0 to 100%, the optimized error amplifier, and the phase compensation circuit.
The S-8541 Series operates under PWM control when the duty ratio is 29% or higher and operates under PFM control when the duty ratio is less than 29% to ensure high efficiency over all load range.
These controllers serve as ideal main power supply units for portable devices due to the high oscillation frequencies together with the small 8-Pin MSOP package.
„ Features • Oscillation frequency • Output voltage • Output voltage precision • Feed back type for output voltage (FB) • External components: • Built-in PWM/PFM switchover control circuit (S-8541 series) • Current limit circuit • Soft-start • Shutdown function • Small package • Lead-free products 600 kHz (A, B types) 300 kHz (C, D types) 1.
5 to 6.
0 V, selectable in 0.
1V steps (A, C types) ±2.
0% a transistor, a coil, a diode, and capacitors Duty ratio: 29% (PFM control) 29 to 100% (PWM control) Current is set by an external resistor RSENSE.
Time is set by a capacitor CSS and a resistor RSS.
8-Pin MSOP „ Applications • Power supplies for PDAs, electric organizers, and portable devices.
• Power supplies for audio equipment ...


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