Moteur de recherche de fiches techniques de composants électroniques
  French  ▼
ALLDATASHEET.FR

X  

FAN5362 Fiches technique(PDF) 9 Page - Fairchild Semiconductor

No de pièce FAN5362
Description  3MHz, 500mA / 750mA Synchronous Buck Regulator
Download  14 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  FAIRCHILD [Fairchild Semiconductor]
Site Internet  http://www.fairchildsemi.com
Logo FAIRCHILD - Fairchild Semiconductor

FAN5362 Fiches technique(HTML) 9 Page - Fairchild Semiconductor

Back Button FAN5362 Datasheet HTML 5Page - Fairchild Semiconductor FAN5362 Datasheet HTML 6Page - Fairchild Semiconductor FAN5362 Datasheet HTML 7Page - Fairchild Semiconductor FAN5362 Datasheet HTML 8Page - Fairchild Semiconductor FAN5362 Datasheet HTML 9Page - Fairchild Semiconductor FAN5362 Datasheet HTML 10Page - Fairchild Semiconductor FAN5362 Datasheet HTML 11Page - Fairchild Semiconductor FAN5362 Datasheet HTML 12Page - Fairchild Semiconductor FAN5362 Datasheet HTML 13Page - Fairchild Semiconductor Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 14 page
background image
© 2009 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN5362 • Rev. 1.0.1
9
Operation Description
FAN5362 is a 500mA or 750mA, step-down switching
voltage regulator that delivers a fixed output voltage from an
input voltage supply up to 5.5V. Using a proprietary
architecture with synchronous rectification, FAN5362 is
capable of delivering a peak efficiency above 96%, while
maintaining efficiency above 90% at load currents as low as
1mA. The regulator operates at a nominal frequency of
3MHz at full load, which reduces the value of the external
components to 1µH for the inductor and 4.7µF for the output
capacitor. High efficiency is maintained at light load with
single-pulse PFM mode.
Control Scheme
The FAN5362 uses a proprietary, non-linear, fixed-
frequency PWM modulator to deliver a fast load transient
response,
while
maintaining
a
constant
switching
frequency over a wide range of operating conditions. The
regulator performance is independent of the output
capacitor ESR, allowing for the use of ceramic output
capacitors. Although this type of operation normally
results in a switching frequency that varies with input
voltage and load current, an internal frequency loop holds
the switching frequency constant over a large range of
input voltages and load currents.
For very light loads, the FAN5362 operates in discontinuous
current (DCM) single-pulse PFM mode, which produces low
output ripple compared with other PFM architectures.
Transition between PWM and PFM is seamless, with a glitch
of less than 18mV at VOUT during the transition between
DCM and CCM modes.
Combined
with
exceptional
transient
response
characteristics, the very low quiescent current of the
controller (45µA) maintains high efficiency, even at very light
loads, while preserving fast transient response for
applications requiring tight output regulation.
100% Duty Cycle Operation
When VIN approaches VOUT, the regulator increases its duty
cycle until 100% duty cycle is reached. As the duty cycle
approaches 100%, the switching frequency declines due to
the minimum off-time (tOFF(MIN)) of about 35ns imposed by the
control circuit. When 100% duty cycle is reached, VOUT
follows VIN with a drop-out voltage (VDROPOUT) determined by
the total resistance between VIN and VOUT:
(
)
L
)
ON
(
DS
LOAD
DROPOUT
DCR
R
PMOS
I
V
+
=
(1)
To calculate the worst-case VDROPOUT, use the maximum
PMOS RDS(ON) at high temperature from Figure 5.
Enable and Soft Start
When the EN pin is LOW, the IC is shut down and the part
draws very little current. In addition, during shutdown, FB is
actively discharged to ground through a 230
Ω path. Raising
EN above its threshold voltage activates the part and starts
the soft-start cycle. During soft-start, the internal reference is
ramped using an exponential RC shape to prevent any
overshoot of the output voltage. Current limiting minimizes
inrush during soft-start.
Synchronous rectification is inhibited during soft-start,
allowing the IC to start into a pre-charged load.
The IC may fail to start if heavy load is applied during startup
and/or if excessive COUT is used. This is due to the current-
limit fault response, which protects the IC in the event of an
over-current condition present during soft-start.
The current required to charge COUT during soft-start is
commonly referred to as “displacement current” and given as:
dt
dV
C
I
OUT
DISP
=
(2)
where
dt
dV
refers to the soft-start slew rate.
To prevent shutdown during soft-start, the following condition
must be met:
)
DC
(
MAX
LOAD
DISP
I
I
I
<
+
(3)
where IMAX(DC) is the maximum load current the IC is
guaranteed to support (500mA or 750mA).
MODE Pin
Logic 1 on this pin forces the IC to stay in PWM mode. A
logic 0 allows the IC to automatically switch to PFM during
light loads. If the MODE pin is toggled, the converter
synchronizes its switching frequency to four times the
frequency on the mode pin (fMODE).
At startup, the mode pin must be held LOW or HIGH for at
least 10
μs to ensure that the converter does not attempt to
synchronize to this pin.
Under-Voltage Lockout
When EN is HIGH, the under-voltage lockout keeps the part
from operating until the input supply voltage rises high
enough to properly operate. This ensures no misbehavior of
the regulator during startup or shutdown.
Current Limiting
A heavy load or short circuit on the output causes the current
in the inductor to increase until a maximum current threshold
is reached in the high-side switch. Upon reaching this point,
the high-side switch turns off, preventing high currents from
causing damage. 16 consecutive PWM cycles in current limit
causes the regulator to shut down and stay off for about
2900
μs before attempting a restart.
In the event of a short circuit, the soft-start circuit attempts to
restart at 240
μs, which results in a duty cycle of less than
10%, providing current into a short.
The closed-loop peak-current limit, ILIM(PK), is not the same
as the open-loop tested current limit, ILIM(OL), in the Electrical
Characteristics table. This is primarily due to the effect of
propagation delays of the IC current limit comparator.


Numéro de pièce similaire - FAN5362

FabricantNo de pièceFiches techniqueDescription
logo
ON Semiconductor
FAN5362 ONSEMI-FAN5362 Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
FAN5362UC21X ONSEMI-FAN5362UC21X Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
FAN5362UC25X ONSEMI-FAN5362UC25X Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
FAN5362UC27X ONSEMI-FAN5362UC27X Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
FAN5362UC29X ONSEMI-FAN5362UC29X Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
More results

Description similaire - FAN5362

FabricantNo de pièceFiches techniqueDescription
logo
ON Semiconductor
FAN5362 ONSEMI-FAN5362 Datasheet
1Mb / 16P
   3MHz, 500mA / 750mA Synchronous Buck Regulator
Rev. 1.0.5
logo
Fairchild Semiconductor
FAN5353 FAIRCHILD-FAN5353 Datasheet
983Kb / 13P
   3MHz, 3A Synchronous Buck Regulator
FAN5354 FAIRCHILD-FAN5354_11 Datasheet
1Mb / 14P
   3MHz, 3A Synchronous Buck Regulator
FAN5354 FAIRCHILD-FAN5354 Datasheet
785Kb / 14P
   3MHz, 3A Synchronous Buck Regulator
FAN5361 FAIRCHILD-FAN5361_10 Datasheet
1Mb / 18P
   6MHz, 600mA / 750mA Synchronous Buck Regulator
logo
Micrel Semiconductor
MIC23451 MICREL-MIC23451 Datasheet
3Mb / 20P
   3MHz, 2A Triple Synchronous Buck Regulator
logo
Intersil Corporation
ISL85415 INTERSIL-ISL85415_13 Datasheet
1Mb / 24P
   Wide VIN 500mA Synchronous Buck Regulator
logo
Altera Corporation
ER3105DI ALTERA-ER3105DI Datasheet
3Mb / 25P
   500mA Wide VIN Synchronous Buck Regulator
logo
Renesas Technology Corp
ISL85415 RENESAS-ISL85415 Datasheet
1Mb / 24P
   Wide VIN 500mA Synchronous Buck Regulator
logo
Intersil Corporation
ISL85415 INTERSIL-ISL85415 Datasheet
1Mb / 23P
   Wide VIN 500mA Synchronous Buck Regulator
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14


Fiches technique Télécharger

Go To PDF Page


Lien URL




Politique de confidentialité
ALLDATASHEET.FR
ALLDATASHEET vous a-t-il été utile ?  [ DONATE ] 

À propos de Alldatasheet   |   Publicité   |   Contactez-nous   |   Politique de confidentialité   |   Echange de liens   |   Fabricants
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com