Datenblatt-Suchmaschine für elektronische Bauteile
  German  ▼
ALLDATASHEETDE.COM

X  

FAN2108MPX Datenblatt(PDF) 10 Page - Fairchild Semiconductor

Teilenummer FAN2108MPX
Bauteilbeschribung  TinyBuck??3-24V Input, 8A, High-Efficiency, Integrated Synchronous Buck Regulator
Download  14 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Hersteller  FAIRCHILD [Fairchild Semiconductor]
Direct Link  http://www.fairchildsemi.com
Logo FAIRCHILD - Fairchild Semiconductor

FAN2108MPX Datenblatt(HTML) 10 Page - Fairchild Semiconductor

Back Button FAN2108MPX Datasheet HTML 6Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 7Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 8Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 9Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 10Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 11Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 12Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 13Page - Fairchild Semiconductor FAN2108MPX Datasheet HTML 14Page - Fairchild Semiconductor  
Zoom Inzoom in Zoom Outzoom out
 10 / 14 page
background image
© 2008 Fairchild Semiconductor Corporation
www.fairchildsemi.com
FAN2108 • Rev. 1.0.0
10
Circuit Description
Initialization
Once VCC exceeds the UVLO threshold and EN is
HIGH, the IC checks for an open or shorted FB pin
before releasing the internal soft-start ramp (SS).
If R1 is open (Figure 1), the error amplifier output
(COMP) is forced LOW and no pulses are generated.
After the SS ramp times out (T1.0), an under-voltage
latched fault occurs.
If the parallel combination of R1 and RBIAS is ≤ 1KΩ, the
internal SS ramp is not released and the regulator does
not start.
Bias Supply
The FAN2108 requires a 5V supply rail to bias the IC
and provide gate-drive energy. Connect a
≥ 1.0µf X5R
or X7R decoupling capacitor between VCC and PGND.
Since VCC is used to drive the internal MOSFET gates,
supply current is frequency and voltage dependent.
Approximate VCC current (ICC) is calculated by:
)]
128
(
)
013
.
0
227
5
[(
58
.
4
)
(
+
+
=
f
V
I
CC
mA
CC
(1)
where frequency (f) is expressed in KHz.
Enable
FAN2108 has an internal pull-up to enable pin so that
the IC is enabled once VCC is applied. Connecting a
small capacitor across EN and AGND delays the rate of
voltage rise on the EN pin. EN pin also serves for the
restart whenever a fault occurs (refer to the Auto-
Restart section)
. For applications where sequencing is
required, FAN2108 can be enabled (after the VCC
comes up) with external control, as shown in Figure 20.
14
FAN2108
EN
3.3n
Figure 20. Enabling with External Control
Setting the Frequency
Oscillator frequency is determined by an external resistor,
RT, connected between the R(T) pin and AGND.
Resistance is calculated by:
65
135
)
/
10
( 6
)
(
=
Ω
f
R
K
T
(2)
where RT is in KΩ and frequency (f) is in KHz.
The regulator cannot start if RT is left open.
Soft-Start
Once internal SS ramp has charged to 0.8V (T0.8), the
output voltage is in regulation. Until SS ramp reaches
1.0V (T1.0), the fault latch is inhibited.
To avoid skipping the soft-start cycle, it is necessary to
apply VIN before VCC reaches its UVLO threshold.
Soft-start time is a function of oscillator frequency.
SS
1.35V
FB
EN
0.8V
T0.8
T1.0
3200 CLKs
4000 CLKs
Fault
Latch
Enable
0.8V
1.0V
2400 CLKs
Figure 21. Soft-Start Timing Diagram
The regulator does not allow the low-side MOSFET to
operate in full synchronous rectification mode until
internal SS ramp reaches 95% of VREF (~0.76V). This
helps the regulator to start on a pre-biased output and
ensures that inductor current does not "ratchet" up
during the soft-start cycle.
VCC UVLO or toggling the EN pin discharges the SS and
resets the IC.
Setting the Output Voltage
The output voltage of the regulator can be set from 0.8V
to 80% of VIN by an external resistor divider (R1 and
RBIAS in Figure 1).
The internal reference is 0.8V with 650nA, sourced from
the FB pin to ensure that, if the pin is open, the
regulator does not start.
The external resistor divider is calculated using:
nA
R
V
V
R
V
OUT
BIAS
650
1
8
.
0
8
.
0
+
=
(3)
Connect RBIAS between FB and AGND.


Ähnliche Teilenummer - FAN2108MPX

HerstellerTeilenummerDatenblattBauteilbeschribung
logo
Fairchild Semiconductor
FAN2108MPX FAIRCHILD-FAN2108MPX_12 Datasheet
759Kb / 14P
   TinyBuck??3-24 V Input, 8 A, High-Efficiency, Integrated Synchronous Buck Regulator
More results

Ähnliche Beschreibung - FAN2108MPX

HerstellerTeilenummerDatenblattBauteilbeschribung
logo
Fairchild Semiconductor
FAN2110 FAIRCHILD-FAN2110 Datasheet
1Mb / 17P
   TinyBuck?? 3-24V Input, 10A, High-Efficiency, Integrated Synchronous Buck Regulator
FAN2106 FAIRCHILD-FAN2106 Datasheet
437Kb / 14P
   TinyBuck 6A, 24V Input Integrated Synchronous Buck Regulator
FAN2106 FAIRCHILD-FAN2106_08 Datasheet
770Kb / 14P
   TinyBuck?? 6A, 24V Input, Integrated Synchronous Buck Regulator
FAN2103 FAIRCHILD-FAN2103_08 Datasheet
964Kb / 14P
   TinyBuck??3A, 24V Input, Integrated Synchronous Buck Regulator
FAN21SV04 FAIRCHILD-FAN21SV04 Datasheet
793Kb / 18P
   TinyBuck??4A, 24V Single-Input Integrated Synchronous Buck Regulator
FAN2106 FAIRCHILD-FAN2106_09 Datasheet
763Kb / 15P
   3-24V Input, 6A, High-Efficiency, Integrated Synchronous Buck Regulator
FAN2106 FAIRCHILD-FAN2106_12 Datasheet
811Kb / 15P
   TinyBuck??3-24 V Input, 6 A, High-Efficiency, Integrated Synchronous Buck Regulator
FAN2108 FAIRCHILD-FAN2108_12 Datasheet
759Kb / 14P
   TinyBuck??3-24 V Input, 8 A, High-Efficiency, Integrated Synchronous Buck Regulator
FAN2110 FAIRCHILD-FAN2110_12 Datasheet
1Mb / 18P
   TinyBuck?? 3-24 V Input, 10 A, High- Efficiency, Integrated Synchronous Buck Regulator
FAN21SV06 FAIRCHILD-FAN21SV06 Datasheet
1Mb / 17P
   TinyBuck??6A, 24V Single-Input Integrated Synchronous Buck Regulator, Synchronization Capability
More results


Html Pages

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


Datenblatt Download

Go To PDF Page


Link URL




Privatsphäre und Datenschutz
ALLDATASHEETDE.COM
War ALLDATASHEET hilfreich?  [ DONATE ] 

Über Alldatasheet   |   Werbung   |   Kontakt   |   Privatsphäre und Datenschutz   |   Linktausch   |   Hersteller
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