Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

FAN6520B Datasheet(PDF) 9 Page - Fairchild Semiconductor

Part # FAN6520B
Description  Single Synchronous Buck PWM Controller
Download  14 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  FAIRCHILD [Fairchild Semiconductor]
Direct Link  http://www.fairchildsemi.com
Logo FAIRCHILD - Fairchild Semiconductor

FAN6520B Datasheet(HTML) 9 Page - Fairchild Semiconductor

Back Button FAN6520B Datasheet HTML 5Page - Fairchild Semiconductor FAN6520B Datasheet HTML 6Page - Fairchild Semiconductor FAN6520B Datasheet HTML 7Page - Fairchild Semiconductor FAN6520B Datasheet HTML 8Page - Fairchild Semiconductor FAN6520B Datasheet HTML 9Page - Fairchild Semiconductor FAN6520B Datasheet HTML 10Page - Fairchild Semiconductor FAN6520B Datasheet HTML 11Page - Fairchild Semiconductor FAN6520B Datasheet HTML 12Page - Fairchild Semiconductor FAN6520B Datasheet HTML 13Page - Fairchild Semiconductor Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 14 page
background image
9
www.fairchildsemi.com
FAN6520B Rev. 1.0.3
Depending upon the whether there is a load application
or a load removal, the response time to a load transient
(ISTEP) is different. The following equations give the
approximate response time interval for application and
removal of a transient load:
where TRISE is the response time to the application of a
positive ISTEP, and TFALL is the response time to a load
removal (negative ISTEP). The worst case response time
can be either at the application or removal of load. Be
sure to check both of these equations at the minimum
and maximum output levels for the worst case response
time.
Input Capacitor Selection
Use a mix of input bypass capacitors to control the volt-
age overshoot across the MOSFETs. Use small ceramic
capacitors for high-frequency decoupling and bulk
capacitors to supply the current needed each time Q1
turns on. Place the small ceramic capacitors physically
close to the MOSFETs and between the drain of Q1 and
the source of Q2. The important parameters for the bulk
input capacitor are the voltage rating and the RMS cur-
rent rating. For reliable operation, select the bulk capaci-
tor with voltage and current ratings above the maximum
input voltage and the largest RMS current required by
the circuit. The capacitor voltage rating should be at least
1.25 times greater than the maximum input voltage and a
voltage rating of 1.5 times is a conservative guideline.
The RMS current rating requirement (IRMS) for the input
capacitor of a buck regulator is:
where the converter duty cycle;
. For a
through-hole design, several electrolytic capacitors may
be needed. For surface-mount designs, solid tantalum
capacitors can be used, but caution must be exercised
with regard to the capacitor’s surge current rating. The
capacitors must be capable of handling the surge current
at power-up. Some capacitor series available from repu-
table manufacturers are surge current tested.
Bootstrap Circuit
The bootstrap circuit uses a charge storage capacitor
(CBOOT) and the internal diode, as shown in Figure 1.
Selection of these components should be done after the
high-side MOSFET has been chosen. The required
capacitance is determined using the following equation:
where QG is the total gate charge of the high-side MOS-
FET, and
∆V
BOOT is the voltage droop allowed on the
high-side MOSFET drive. To prevent loss of gate drive,
the bootstrap capacitance should be at least 50 times
greater than the CISS of Q1. If FB is < 800mV for 32 con-
secutive cycles, then LDRV is turned on for ~1.6µs to
charge the bootstrap capacitor.
Thermal Considerations
Total device dissipation:
PD = PQ + PHDRV + PLDRV
(4)
where PQ represents quiescent power dissipation:
PQ = VCC × 2.7mA
(5)
PHDRV represents internal power dissipation of the upper
FET driver.
PHDRV = PH(R) × PH(F)
(6)
Where PH(R) and PH(F) are internal dissipations for the
rising and falling edges respectively:
where:
PQ1 = QG1 × VGS(Q1) × FSW
(9)
Where QG1 is total gate charge of Q1 for its applied VGS.
As described in the equations above, the total power
consumed in driving the gate is divided in proportion to
the resistances in series with the MOSFET's internal
gate node as shown in Figure 8.
Figure 8. Driver Dissipation Model
RG is the polysilicon gate resistance, internal to the FET.
RE is the external gate drive resistor implemented in
many designs. Note that the introduction of RE can
reduce driver power dissipation, but excess RE may
cause errors in the “adaptive gate drive” circuitry. For
more information please refer to Fairchild app note
AN-6003, “Shoot-through” in Synchronous Buck Con-
verters. (http://www.fairchildsemi.com/an/AN/AN-6003.pdf)
T
RISE
LI
STEP
×
V
IN
V
OUT
------------------------------
=
T
FALL
LI
STEP
×
V
OUT
------------------------
=
I
RMS
I
L
DD
2
()
=
(2)
D
V
OUT
V
IN
--------------
=
C
BOOT
Q
G
∆V
BOOT
----------------------
=
(3)
P
HR
()
P
Q1
R
HUP
R
HUP
R
E
R
G
++
-------------------------------------------
×
=
(7)
P
HF
()
P
Q1
R
HDN
R
HDN
R
E
R
G
++
--------------------------------------------
×
=
(8)
HDRV
Q1
G
R
G
RE
RHUP
BOOT
SW
R
HDN
S


Similar Part No. - FAN6520B

ManufacturerPart #DatasheetDescription
logo
Fairchild Semiconductor
FAN6520A FAIRCHILD-FAN6520A Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
FAN6520A FAIRCHILD-FAN6520A Datasheet
482Kb / 15P
   Single Synchronous Buck PWM Controller
FAN6520AIM FAIRCHILD-FAN6520AIM Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
FAN6520AIM FAIRCHILD-FAN6520AIM Datasheet
482Kb / 15P
   Single Synchronous Buck PWM Controller
FAN6520AIMX FAIRCHILD-FAN6520AIMX Datasheet
580Kb / 15P
   Single Synchronous Buck PWM Controller
More results

Similar Description - FAN6520B

ManufacturerPart #DatasheetDescription
logo
Fairchild Semiconductor
FAN6520A FAIRCHILD-FAN6520A_06 Datasheet
482Kb / 15P
   Single Synchronous Buck PWM Controller
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
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


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
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