Zakładka z wyszukiwarką danych komponentów
  Polish  ▼
ALLDATASHEET.PL

X  

FAN6520AIM Arkusz danych(PDF) 6 Page - Fairchild Semiconductor

Numer części FAN6520AIM
Szczegółowy opis  Single Synchronous Buck PWM Controller
Download  15 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Producent  FAIRCHILD [Fairchild Semiconductor]
Strona internetowa  http://www.fairchildsemi.com
Logo FAIRCHILD - Fairchild Semiconductor

FAN6520AIM Arkusz danych(HTML) 6 Page - Fairchild Semiconductor

Back Button FAN6520AIM Datasheet HTML 2Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 3Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 4Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 5Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 6Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 7Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 8Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 9Page - Fairchild Semiconductor FAN6520AIM Datasheet HTML 10Page - Fairchild Semiconductor Next Button
Zoom Inzoom in Zoom Outzoom out
 6 / 15 page
background image
©2005 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN6520A Rev. 1.0.5
6
Circuit Description
Initialization
The FAN6520A automatically initializes upon receipt of
power. The Power-On Reset (POR) function continually
monitors the bias voltage at the VCC pin. When the sup-
ply voltage exceeds its POR threshold, the IC initiates
the Over-Current Protection (OCP) sample-and-hold
operation. Upon completion of the OCP sample-and-hold
operation, the POR function initiates soft-start operation.
Over-Current Protection
The over-current function protects the converter from a
shorted output by using the upper MOSFET’s on-resis-
tance, RDS(ON), to monitor the current. This method
enhances the converter’s efficiency and reduces cost by
eliminating the need for a current-sensing resistor. The
over-current function cycles the soft-start function in a
hiccup mode to provide fault protection. A resistor (ROC-
SET) programs the over-current trip level (see Typical
Application diagram). Immediately following POR, the
FAN6520A initiates the Over-Current Protection sam-
pling-and-hold operation. First, the internal error ampli-
fier is disabled. This allows an internal 20µA current sink
to develop a voltage across ROCSET. The FAN6520A
then samples this voltage at the COMP pin. This sam-
pled voltage, which is referenced to the VCC pin, is held
internally as the over-current set point. When the voltage
across the upper MOSFET, which is also referenced to
the VCC pin, exceeds the over-current set point, the
over-current function initiates a soft-start sequence. Fig-
ure 3 shows the inductor current after a fault is intro-
duced while running at 15A. The continuous fault causes
the FAN6520A to go into a hiccup mode with a typical
period of 25ms. The inductor current increases to 18A
during the soft-start interval and causes an over-current
trip. The converter dissipates very little power with this
method. The measured input power for the conditions
shown in Figure 3 is 1.5W.
Figure 3. Over-Current Operation
The over-current function trips at a peak inductor current
(IPEAK) determined by:
where IOCSET is the internal OCSET current source
(20µA typical). The OC trip point varies mainly due to the
MOSFET’s RDS(ON) variations. To avoid over-current
tripping in the normal operating load range, find the ROC-
SET resistor from the equation above with:
• The maximum RDS(ON) at the highest junction
temperature
• The minimum IOCSET from the specification table
• Determine IPEAK for
where
ΔI is the output inductor ripple current.
For an equation for the ripple current, see “Output Induc-
tor (Lout)” under Component Selection.
Internal circuitry of the FAN6520A does not recognize a
voltage drop across ROCSET larger than 0.5V. Any volt-
age drop across ROCSET greater than 0.5V sets the over-
current trip point to:
An over-current trip cycles the soft-start function.
Soft-Start
The POR function initiates the soft-start sequence after
the over-current set point has been sampled. Soft-start
clamps the error amplifier output (COMP pin) and refer-
ence input (noninverting terminal of the error amp) to the
internally generated soft-start voltage. Figure 4 shows a
typical start-up interval where the COMP/OCSET pin has
been released from a grounded (system shutdown)
state. Initially, the COMP/OCSET is used to sample the
over-current set point by disabling the error amplifier and
drawing 20µA through ROCSET. Once the over-current
level has been sampled, the soft-start function is initi-
ated. The clamp on the error amplifier (COMP/OCSET
pin) initially controls the converter’s output voltage during
soft-start. The oscillator’s triangular waveform is com-
pared to the ramping error amplifier voltage. This gener-
ates SW pulses of increasing width that charge the
output capacitor(s). When the internally generated soft-
start voltage exceeds the feedback (FB pin) voltage, the
output voltage is in regulation. This method provides a
rapid and controlled output voltage rise. The entire start-
up sequence typically takes about 11ms.
OUTPUT INDUCTOR
CURRENT
5A/DIV.
I
PEAK
I
OCSET
R
OCSET
×
R
DS ON
()
-----------------------------------------------
=
(1)
I
PEAK
I
OUT MAX
()
ΔI
2
-----
+
>
I
PEAK
0.5V
R
DS ON
()
----------------------
=
(2)


Podobny numer części - FAN6520AIM

ProducentNumer częściArkusz danychSzczegółowy opis
logo
Fairchild Semiconductor
FAN6520AIM FAIRCHILD-FAN6520AIM Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
FAN6520AIMX FAIRCHILD-FAN6520AIMX Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
More results

Podobny opis - FAN6520AIM

ProducentNumer częściArkusz danychSzczegółowy opis
logo
Taiwan Semiconductor Co...
TS3404 TSC-TS3404_1 Datasheet
379Kb / 10P
   Single Synchronous Buck PWM Controller
logo
Fairchild Semiconductor
FAN6520A FAIRCHILD-FAN6520A Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
logo
Richtek Technology Corp...
RT8238B RICHTEK-RT8238B Datasheet
219Kb / 15P
   Single Synchronous Buck PWM Controller
logo
Taiwan Semiconductor Co...
TS3405 TSC-TS3405 Datasheet
409Kb / 10P
   Single Synchronous Buck PWM Controller
logo
Richtek Technology Corp...
RT8228A RICHTEK-RT8228A Datasheet
201Kb / 15P
   Single Synchronous Buck PWM Controller
October 2021
logo
Fairchild Semiconductor
FAN6520B FAIRCHILD-FAN6520B Datasheet
550Kb / 14P
   Single Synchronous Buck PWM Controller
logo
BCD Semiconductor Manuf...
AP3586A,B,C BCDSEMI-AP3586A,B,C Datasheet
624Kb / 17P
   Single Phase Synchronous Buck PWM Controller
AP3581A,B,C BCDSEMI-AP3581A,B,C Datasheet
575Kb / 13P
   Single Phase Synchronous Buck PWM Controller
logo
Richtek Technology Corp...
RT8120 RICHTEK-RT8120_V01 Datasheet
223Kb / 17P
   Single-Phase Synchronous Buck PWM Controller
logo
Diodes Incorporated
AP3581A DIODES-AP3581A Datasheet
756Kb / 13P
   SINGLE PHASE SYNCHRONOUS BUCK PWM CONTROLLER
November 2018 Rev. 2 - 4
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


Arkusz danych Pobierz

Go To PDF Page


Link URL




Polityka prywatności
ALLDATASHEET.PL
Czy Alldatasheet okazała się pomocna?  [ DONATE ] 

O Alldatasheet   |   Reklama   |   Kontakt   |   Polityka prywatności   |   Linki   |   Lista producentów
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