|
|
PDF FR9884 Data sheet ( Hoja de datos )
| Número de pieza | FR9884 | |
| Descripción | 340KHz Synchronous Step-Down DC/DC Converter | |
| Fabricantes | Fiti | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de FR9884 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
|
No Preview Available !
fitipower integrated technology lnc.
FR9884
18V, 3A, 340KHz Synchronous Step-Do8w5nT
DC/DC Converter
Description
The FR9884 is a synchronous step-down DC/DC
converter that provides wide 4.5V to 18V input
voltage range and 3A continuous load current
capability.
Fault protection includes cycle-by-cycle current limit,
input UVLO, output over voltage protection and
thermal shutdown. Besides, adjustable soft-start
function prevents inrush current at turn-on. This
device uses current mode control scheme that
provides fast transient response. In shutdown
mode, the supply current is about 10μA.
The FR9884 is available in an 8-pin SOIC package,
which provides a very compact system solution and
good thermal conductance.
Features
● Wide Input Voltage from 4.5V to 18V
● 3A Output Current
● Adjustable Output Voltage from 0.925V to 14V
● Low Rds(on) Integrated Power MOSFET
● High Efficiency up to 93%
● Fixed 340KHz Switching Frequency
● Current Mode Operation
● Adjustable Soft-Start
● Cycle-by-Cycle Current Limit
● Input Under Voltage Lockout
● Over-Temperature Protection With Auto Recovery
● 10μA Shutdown Current
● Thermal Enhanced SOP-8 (Exposed Pad) Package
● RoHS Compliant
Applications
● Set-Top-Box
● DVD,LCD Display
● OLPC, Netbook
● Distributed Power System
● Datacom, XDSL
Pin Assignments
SP Package (SOP-8 Exposed Pad)
BS
VIN
SW
GND
1
2
3
4
8 SS
7 EN
6 COMP
5 FB
Figure 1. Pin Assignment of FR9884
Ordering Information
FR9884□□□
TR: Tape / Reel
G: Green
Package Type
SP: SOP-8 (Exposed Pad)
FR9884-1.7-DEC-2011
1
1 page  
fitipower integrated technology lnc.
Electrical Characteristics
(VIN=12V, TA=25°C, unless otherwise specified.)
Parameter
VIN Input Supply Voltage (Note 2)
VIN Supply Current
VIN Shutdown Supply Current
Feedback Voltage
Feedback OVP Threshold Voltage
High-Side MOSFET RDS(ON) (Note 3)
Low-Side MOSFET RDS(ON) (Note 3)
High-Side MOSFET Leakage Current
High-Side MOSFET Current Limit (Note 3)
Low-Side MOSFET Current Limit (Note 3)
Conditions
VEN = 1.8V
VEN = 0V
4.5V≦VIN≦18V
VEN = 0V, VSW = 0V
Minimum Duty
Current sense to COMP Transconductance (Note 3)
Error Amplifier Transconductance (Note 3)
ΔICOMP = ±10μA
Error Amplifier Voltage Gain (Note 3)
Oscillation frequency
Short Circuit Oscillation Frequency
VFB = 0V
Maximum Duty Cycle
VFB = 0.8V
Minimum On Time (Note 3)
Input UVLO Threshold
VIN Rising
Under Voltage Lockout Threshold Hysteresis
Soft-Start Current
Soft-Start Period
EN Lockout Threshold Voltage
EN Shutdown Threshold Voltage
CSS = 0.1μF
Thermal Shutdown Threshold (Note 3)
Note 2：When VIN = 4.5V, VOUT = 3.3V, maximum load current is about 2A.
Note 3：Not production tested.
FR9884
85T
Min Typ Max Unit
4.5 18 V
1.1 mA
10 15 μA
0.9 0.925 0.95
V
1.3 V
120 mΩ
80 mΩ
10 μA
3.8 5
A
3A
3.5 A/V
1600
μA/V
400 V/V
280 340 400 KHz
110 KHz
90 %
200 ns
4.4 V
400 mV
6 μA
15 ms
2.3 2.5 2.7
V
1.1 1.4
V
160 °C
FR9884-1.7-DEC-2011
5
5 Page 
fitipower integrated technology lnc.
Application Information (Continued)
FR9884
85T
Output Inductor Selection
The output inductor is used for storing energy and
filtering output ripple current. But the trade-off
condition often happens between maximum energy
storage and the physical size of the inductor. The
first consideration for selecting the output inductor is
to make sure that the inductance is large enough to
keep the converter in the continuous current mode.
That will lower ripple current and result in lower
output ripple voltage. A good rule for determining
the inductance is setting the peak-to-peak inductor
ripple current ΔI almost equal to 30% of the
maximum load current. Then the minimum
inductance can be calculated with the following
equation:
I 0.3 IOUT(MAX)
L
VIN
VOUT
VOUT
FOSC I
VIN
Where VIN is the maximum input voltage.
Compensation Components Selection
C7
(optional)
C5
R4
COMP
FR9884
Select the appropriate compensation value by
following procedure:
1. Calculate the R4 value with the following equation:
R4 2 COUT 0.1 FOSC VOUT
GEA GCS VREF
where GEA is the error amplifier voltage gain, and
GCS is the current sense gain.
2. Calculate the C5 value with the following equation:
C5
4
2 R4 0.1 FOSC
3. If the COUT ESR zero is less than half of the
switching frequency, use C7 to cancel the
ESR zero:
C7 COUT RESR
R4
External Boost Diode Selection
For 5V input applications, it is recommended that an
external boost diode could be added. This helps
improving the efficiency. The boost diode can be a
low cost one such as 1N4148.
D1
1N4148
VIN VIN
BS
5V
FR9884
C4
SW
This diode is also recommended for high duty cycle
operation (when duty cycle > 65%, VIN < 15V).
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. The traces
which connect to these capacitors should be as
short and wide as possible to minimize parasitic
inductance and resistance.
2. Place VIN capacitors close to the VIN pin.
3. Place feedback resistors close to the FB pin.
4. Place compensation components close to the
COMP pin.
5. Keep the sensitive signal (FB, COMP) away from
the switching signal (SW).
6. 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
which connects to the exposed pad should be
maximized to improve thermal performance.
7. Multi-layer PCB design is recommended.
FR9884-1.7-DEC-2011
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet FR9884.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| FR9882 | 340KHz Synchronous Step-Down DC/DC Converter | Fiti |
| FR9884 | 340KHz Synchronous Step-Down DC/DC Converter | Fiti |
| FR9885 | Synchronous Step-Down DC/DC Converter | Fiti |
| FR9886 | 380KHz Synchronous Step-Down DC/DC Converter |  fitipower integrated technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |