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PDF FR9806 Data sheet ( Hoja de datos )
| Número de pieza | FR9806 | |
| Descripción | 500KHz Synchronous PWM-Buck DC/DC Converter | |
| Fabricantes | Fiti | |
| Logotipo |  |
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fitipower integrated technology lnc.
FR9806
21V, 3A, 500KHz Synchronous PWM-Bu8c5kT
DC/DC Converter
Description
FR9806 is a high-efficiency synchronous step-down
DC/DC converter that employs a special process
technique to obtain very low RDS(ON) for the internal
metal–oxide–semiconductor field-effect transistor
(MOSFET). The input operation voltage is in a wide
4.75V to 21V, and continuous load current capability
is 3A. Control circuit is designed by a particular
current mode which provides fast transient response
and eases loop stabilization.
This product has a very low standby current less
than 1μA in shutdown mode. When the EN/SYNC
pin voltage is less than 0.4V, FR9806 will turn off.
Fault protection includes over current protection
(OCP), under voltage lockout protection (UVLO) and
over temperature protection (OTP) function.
This high-efficiency current mode step-down “Green
Power Converter” offers the standard SOP-8
package with an exposed pad.
Features
● High Efficiency up to 90%
● Internal MOSFET RDS(ON): 130mΩ/20mΩ
● Internal Compensation
● Input Operation Voltage Range: 4.75V to 21V
● 3A Continuous Output Current
● Output Voltage down to 0.805V
● 500KHz Oscillation Frequency
● Sync to External Clock from 300 KHz to 800 KHz
● Cycle-by-Cycle Current Limit
● Under Voltage Lockout
● Over-Temperature Protection with Auto Recovery
● <1μA Shutdown Current
● Thermal Enhanced SOP-8 (Exposed Pad) Package
● RoHS Compliant
Applications
● Networking equipment
● OLPC, Netbook
● Distributed power system
● LCD monitor, TV, STB
● External HDD
● Security System
Pin Assignments
SP Package (SOP- 8 Expose pad )
VIN 1
8 GND
SW 2 9 7 VCC
SW 3 GND 6 FB
BS 4
5 EN/SYNC
Ordering Information
FR9806□□□
TR: Tape / Reel
G: Green
Package Type
SP: SOP-8 (Exposed Pad)
Figure 1. Pin Assignment of FR9806
FR9806-1.1-SEP-2011
1
1 page  
fitipower integrated technology lnc.
Electrical Characteristics
(VIN=12V, TA=25℃, unless otherwise specified.)
Parameter
Symbol
Conditions
Min
Input Supply Voltage
VIN Shutdown Supply Current
VIN Quiescent Supply Current
Feedback Voltage
High-Side MOSFET RDS(ON) (Note2)
Low-Side MOSFET RDS(ON) (Note2)
VIN
ISD VEN = 0V
IDDQ
VEN = 2 V, VFB = 1 V
VFB 4.75V≦VIN≦21V
HSRDS(ON)
LSRDS(ON)
4.75
780
MOSFET Leakage Current
ISW(Leak) VEN=0V, VSW = 0V
High-Side MOSFET Current Limit
(Note2)
ILIMIT
Maximum Duty Cycle
DMAX
VFB = 0.7 V
Oscillation frequency
FSW
Short-Circuit Oscillation Frequency
FSW(Short) VFB = 0.3 V
Sync Frequency Range
FSYNC
Input UVLO Threshold
Under Voltage Lockout
Hysteresis
EN/SYNC Input Low Voltage
Threshold
VUVLO(Vth)
VUVLO(Hys)
VEN(L)
VIN Rising
EN/SYNC Input High Voltage
VEN(H)
EN Input Current
IEN VEN = 2 V
VCC Regulator
VCC
Soft-Start Time
TSS
Thermal Shutdown Threshold (Note 2)
Note 2：Guarantee by design.
TSD
350
300
2.0
FR9806
85T
Typ Max Unit
21 V
1 μA
1.1 mA
805 830 mV
130 mΩ
20 mΩ
0 10 μA
6A
90 %
500 650 KHz
150 KHz
800 KHz
4V
200 mV
0.4
2
4.5
600
160
V
V
μA
V
μs
°C
FR9806-1.1-SEP-2011
5
5 Page 
fitipower integrated technology lnc.
Application Information (Continued)
FR9806
85T
Feedforward Capacitor Selection
Internal compensation function allows users saving
time in design and saving cost by reducing the
number of external components. The use of a
feedforward capacitor C6 in the feedback network is
recommended to improve the transient response or
higher phase margin.
VOUT
FR9806
FB
R1 C6
R2
For optimizing the feedforward capacitor, knowing
the cross frequency is the first thing. The cross
frequency (or the converter bandwidth) can be
determined by using a network analyzer. When
getting the cross frequency with no feedforward
capacitor identified, the value of feedforward
capacitor C6 can be calculated with the following
equation:
C6
1
2 FCROSS
1
R1
1
R1
1
R2
Where FCROSS is the cross frequency.
To reduce transient ripple, the feedforward capacitor
value can be increased to push the cross frequency
to higher region. Although this can improve
transient response, it also decrease phase margin
and cause more ringing. In the other hand, if more
phase margin is desired, the feedforward capacitor
value can be decreased to push the cross frequency
to lower region. In general, the feedforward
capacitor range is between 10pF to 1nF.
External Diode Selection
For 5V input applications, it is recommended to add
an external bootstrap diode. This helps improving
efficiency. The bootstrap diode can be a low cost
one such as 1N4148.
D1
1N4148
PCB Layout Recommendation
The device’s performance and stability are
dramatically affected by PCB layout. It is
recommended to follow these general guidelines
shown as below:
1. Place the input capacitors and output capacitors
as close to the device as possible. Trace to
these capacitors should be as short and wide as
possible to minimize parasitic inductance and
resistance.
2. Place feedback resistors close to the FB pin.
3. Keep the sensitive signal (FB) away from the
switching signal (SW).
4. The exposed pad of the package should be
soldered to an equivalent area of metal on the
PCB. This area should connect to the GND
plane and have multiple via connections to the
back of the PCB as well as connections to
intermediate PCB layers. The GND plane area
connecting to the exposed pad should be
maximized to improve thermal performance.
5. Multi-layer PCB design is recommended.
C6
R3 R1
R2
8765
Exposed
GND
Pad
–
C1
+
C5
1234
VIN C4 LX
GND
L1
–
C2
+
VOUT
Figure 23. FR9806 SOP-8 (Exposed Pad) package
CIN/COUT with EC capacitors Recommended PCB
Layout Diagram
VIN VIN
BS
5V
FR9806
C4
SW
FR9806-1.1-SEP-2011
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet FR9806.PDF ] | |
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