|
|
PDF RT8279 Data sheet ( Hoja de datos )
| Número de pieza | RT8279 | |
| Descripción | 500kHz Step-Down Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de RT8279 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
|
No Preview Available !
RT8279
5A, 36V, 500kHz Step-Down Converter
General Description
The RT8279 is a step-down regulator with an internal power
MOSFET. It achieves 5A of continuous output current over
a wide input supply range with excellent load and line
regulation. Current mode operation provides fast transient
response and eases loop stabilization.
For protection, the RT8279 provides cycle-by-cycle current
limiting and thermal shutdown protection. An adjustable
soft-start reduces the stress on the input source at
startup. In shutdown mode, the regulator draws only 25μA
of supply current.
The RT8279 requires a minimum number of readily
available external components, providing a compact
solution. The RT8279 is available in the SOP-8 (Exposed
Pad) package.
Ordering Information
RT8279
Package Type
SP : SOP-8 (Exposed Pad-Option 1)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
RT8279
GSPYMDNN
RT8279GSP : Product Number
YMDNN : Date Code
Features
z 5A Output Current
z Internal Soft-Start
z 110mΩ Internal Power MOSFET Switch
z Internal Compensation Minimizes External Parts
Count
z High Efficiency up to 90%
z 25μA Shutdown Mode
z Fixed 500kHz Frequency
z Thermal Shutdown
z Cycle-by-Cycle Over Current Protection
z Wide 5.5V to 36V Operating Input Range
z Adjustable Output Voltage from 1.222V to 26V
z Available In an SOP8 (Exposed Pad) Package
z RoHS Compliant and Halogen Free
Applications
z Distributive Power Systems
z Battery Charger
z DSL Modems
Pre-regulator for Linear Regulatorshttp://www.DataSheet4U.net/
z
Pin Configurations
(TOP VIEW)
BOOT
NC
NC
FB
8
2 GND 7
36
9
45
SW
VIN
GND
EN
SOP-8 (Exposed Pad)
DS8279-01 December 2011
www.richtek.com
1
datasheet pdf - http://www.DataSheet4U.net/
1 page  
RT8279
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
http://www.DataSheet4U.net/
DS8279-01 December 2011
www.richtek.com
5
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
recovery time, VOUT can be monitored for overshoot or
ringing that would indicate a stability problem.
EMI Consideration
Since parasitic inductance and capacitance effects in PCB
circuitry would cause a spike voltage on SW pin when
high side MOSFET is turned-on/off, this spike voltage on
SW may impact on EMI performance in the system. In
order to enhance EMI performance, there are two methods
to suppress the spike voltage. One is to place an R-C
RT8279
snubber between SW and GND and make them as close
as possible to the SW pin (see Figure 3). Another method
is to add a resistor in series with the bootstrap
capacitor, CBOOT. But this method will decrease the driving
capability to the high side MOSFET. It is strongly
recommended to reserve the R-C snubber during PCB
layout for EMI improvement. Moreover, reducing the SW
trace area and keeping the main power in a small loop will
be helpful on EMI performance. For detailed PCB layout
guide, please refer to the section of Layout Consideration.
VIN
5.5V to 32V
REN*
CEN*
CIN 7 VIN
BOOT 1
4.7µF x 2
RT8279
5 EN
SW 8
6, 9 (Exposed Pad) GND
FB 4
RBOOT*
RS*
CS*
CBOOT L
10nF 10µH
D
B550C
* : Optional
R1
10k
R2
3.16k
Figure 3. Reference Circuit with Snubber and Enable Timing Control
VOUT
5V/5A
COUT
47µFx2
(POSCAP)
Thermal Considerations
For continuous operation, do not exceed the maximum
operation junction temperature. The maximum power
dissipation depends on the thermal resistance of IC
package, PCB layout, the rate of surroundings airflow and
temperature difference between junction to ambient. The
maximum power dissipation can be calculated by following
formula :
PD(MAX) = (TJ(MAX) − TA ) / θJA
Where TJ(MAX) is the maximum operation junction
temperature , TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT8279, the maximum junction temperature is 125°C. The
junction to ambient thermal resistance θJA is layout
dependent. For PSOP-8 package, the thermal resistance
θJA is 75°C/W on the standard JEDEC 51-7 four-layers
thermal test board. The maximum power dissipation at
TA = 25°C can be calculated by following formula :
http://www.DataSheet4U.net/
PD(MAX)
= (125°C − 25°C) / (75°C/W)
(min.copper area PCB layout)
= 1.333W
PD(MAX) = (125°C − 25°C) / (49°C/W) = 2.04W (70mm2
copper area PCB layout)
The thermal resistance θJA of SOP-8 (Exposed Pad) is
determined by the package architecture design and the
PCB layout design. However, the package architecture
design had been designed. If possible, it's useful to
increase thermal performance by the PCB layout copper
design. The thermal resistance θJA can be decreased by
adding copper area under the exposed pad of SOP-8
(Exposed Pad) package.
As shown in Figure 4, the amount of copper area to which
the SOP-8 (Exposed Pad) is mounted affects thermal
performance. When mounted to the standard
SOP-8 (Exposed Pad) pad (Figure 4a), θJA is 75°C/W.
Adding copper area of pad under the SOP-8 (Exposed
Pad) (Figure 4.b) reduces the θJA to 64°C/W. Even further,
increasing the copper area of pad to 70mm2 (Figure 4.e)
reduces the θJA to 49°C/W.
DS8279-01 December 2011
www.richtek.com
11
datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT8279.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| RT8270 | 1.2MHz Step-Down Converter | Richtek |
| RT8271 | 1.2MHz Step-Down Converter | Richtek |
| RT8272 | 1.2MHz Step-Down Converter | Richtek |
| RT8278 | 3MHz Step-Down Converter | Richtek |
| 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 |