Os motores de busca de Datasheet de Componentes eletrônicos
  Portuguese  ▼
ALLDATASHEETPT.COM

X  

FAN6520AIMX Folha de dados(PDF) 11 Page - Fairchild Semiconductor

Nome de Peças FAN6520AIMX
Descrição Electrónicos  Single Synchronous Buck PWM Controller
Download  15 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricante Electrônico  FAIRCHILD [Fairchild Semiconductor]
Página de início  http://www.fairchildsemi.com
Logo FAIRCHILD - Fairchild Semiconductor

FAN6520AIMX Folha de dados(HTML) 11 Page - Fairchild Semiconductor

Back Button FAN6520AIMX Datasheet HTML 7Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 8Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 9Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 10Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 11Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 12Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 13Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 14Page - Fairchild Semiconductor FAN6520AIMX Datasheet HTML 15Page - Fairchild Semiconductor  
Zoom Inzoom in Zoom Outzoom out
 11 / 15 page
background image
PRODUCT SPECIFICATION
FAN6520A
REV. 1.0.2 8/26/04
11
Power MOSFET Selection
For more information on MOSFET selection for synchro-
nous buck regulators, refer to: AN-6005: Synchronous Buck
MOSFET Loss Calculations.
This Fairchild app note is located at:
http://www.fairchildsemi.com/an/AN/AN-6005.pdf
Losses in a MOSFET are the sum of its switching (PSW) and
conduction (PCOND) losses.
In typical applications, the FAN6520A converter's output
voltage is low with respect to its input voltage, therefore the
lower MOSFET (Q2) is conducting the full load current for
most of the cycle. Therefore choose a MOSFET for Q2
which has low RDS(ON) to minimize conduction losses.
In contrast, the high-side MOSFET (Q1) has a much shorter
duty cycle, and its conduction loss will therefore have less of
an impact. Q1, however, sees most of the switching losses,
so Q1’s primary selection criteria should be gate charge.
High-Side Losses
Figure 10 shows a MOSFET’s switching interval, with the
upper graph being the voltage and current on the Drain to
Source and the lower graph detailing VGS vs. time with a
constant current charging the gate. The x-axis, therefore, is
also representative of gate charge (QG) . CISS = CGD + CGS,
and it controls t1, t2, and t4 timing. CGD receives the current
from the gate driver during t3 (as VDS is falling). The gate
charge (QG) parameters on the lower graph are either
specified or can be derived from the MOSFET’s datasheet.
Assuming switching losses are about the same for both the
rising edge and falling edge, Q1’s switching losses, occur
during the shaded time when the MOSFET has voltage
across it and current through it.
These losses are given by:
PUPPER = PSW + PCOND
where:
PUPPER is the upper MOSFET’s total losses, and PSW and
PCOND are the switching and conduction losses for a given
MOSFET. RDS(ON) is at the maximum junction temperature
(TJ). tS is the switching period (rise or fall time) and is t2+t3
(Figure 10).
The driver’s impedance and CISS determine t2 while t3’s
period is controlled by the driver’s impedance and QGD.
Since most of tS occurs when VGS = VSP we can use a
constant current assumption for the driver to simplify the
calculation of tS:
Figure 10. Switching Losses and QG
Figure 11. Drive Equivalent Circuit
Most MOSFET vendors specify QGD and QGS. QG(SW) can
be determined as: QG(SW) = QGD + QGS – QTH where QTH is
the gate charge required to get the MOSFET to its threshold
(VTH). For the high-side MOSFET, VDS = VIN, which can be
as high as 20V in a typical portable application. Care should
also be taken to include the delivery of the MOSFET’s gate
power (PGATE) in calculating the power dissipation required
for the FAN6520A:
PGATE = QG × VCC × FSW
(17)
where QG is the total gate charge to reach VCC.
P
SW
V
DS
I
L
×
2
---------------------
2
×
t
s
×

 F
SW
=
(14)
P
COND
V
OUT
V
IN
--------------

 I
OUT
2
×
R
DS ON
()
×
=
(15)
V
SP
t1
t2
t3
4.5V
t4
t5
Q
G(SW)
V
DS
I
D
Q
GS
Q
GD
V
TH
V
GS
C
ISS
C
GD
C
ISS
C
GD
R
D
R
GATE
CGS
HDRV
5V
SW
VIN
G
t
s
Q
GSW
()
I
DRIVER
---------------------
Q
GSW
()
VCC
V
SP
R
DRIVER
R
GATE
+
------------------------------------------------


------------------------------------------------------
≈≈
(16)


Nº de peça semelhante - FAN6520AIMX

Fabricante ElectrônicoNome de PeçasFolha de dadosDescrição Electrónicos
logo
Fairchild Semiconductor
FAN6520AIMX FAIRCHILD-FAN6520AIMX Datasheet
482Kb / 15P
   Single Synchronous Buck PWM Controller
More results

Descrição semelhante - FAN6520AIMX

Fabricante ElectrônicoNome de PeçasFolha de dadosDescrição Electrónicos
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
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


Folha de dados Download

Go To PDF Page


Ligação URL




Privacy Policy
ALLDATASHEETPT.COM
ALLDATASHEET é útil para você?  [ DONATE ] 

Sobre Alldatasheet   |   Publicidade   |   Contato conosco   |   Privacy Policy   |   roca de Link   |   Lista de Fabricantes
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