REGULATOR CONTROLLER. S-8541 Datasheet

S-8541 CONTROLLER. Datasheet pdf. Equivalent

Part S-8541
Description (S-8540 / S-8541) 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Feature Rev.3.2_00 www.DataSheet4U.com STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGUL.
Manufacture Seiko Instruments
Datasheet
Download S-8541 Datasheet




S-8541
www.DaRtaeSvhe.e3t4.2U_.c0o0m
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 step-
down switching regulator controllers with PWM control
(S-8540 Series) and PWM/PFM switchover control (S-
8541 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 such as portable CD players and headphone stereos.
Main or sub Power supplies for notebook computers and peripheral equipment.
„ Package
Package Name
8-Pin MSOP
Package
FN008-A
Drawing Code
Tape
FN008-A
Reel
FN008-A
Seiko Instruments Inc.
1



S-8541
www.DaStaTSEhPe-eDt4OUW.coNm, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
S-8540/8541 Series
Rev.3.2_00
„ Block Diagrams
1. A, C types (fixed output voltage)
Pch Pow er
MOS FET
VIN
L
VIN Powe r for IC
T riangu lar wave
o scillatio n circu it
E XT
PWM comp arato r
SE NS E
Phase
com pen satio n
circuit
SD
CIN
PWM or
PWM / PFM
switch ing
Sh utdo wn soft start
circuit
Erro r a mplifier
VREF=1.0 V
Vo ltage/c urrent
referen ce
RS ENS E
125 mV
VO UT
COUT
V SS
O N/O FF
RS S
CS S
V ON/ OFF
CVREF
CVL
Figure 1
2. B, D types (feed back)
Pch Power
MOS FET
VIN
L
VI N
Power for IC
Trian gula r wave
oscill ation circuit
E XT
PWM com parato
SE NS E
Phase
com pensation
circuit
SD
CIN
PWM or
PWM / PF M
switchin g
Sh utdown soft start
circ uit
Error amplifier
VREF=1.0 V
Voltag e/current
reference
RS ENS E
125 mV
VO UT
CFB
FB
V SS
V OUT
RA
COUT
RB
O N/O FF
RS S
CSS
V ON/ OFF
CVREF
CV L
Figure 2
2 Seiko Instruments Inc.







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