|
|
PDF AP2953A Data sheet ( Hoja de datos )
| Número de pieza | AP2953A | |
| Descripción | 18V Synchronous Rectified Step-Down Converter | |
| Fabricantes | Chipown | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AP2953A (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
|
No Preview Available !
AP2953A
Description
The AP2953A is a monolithic synchronous buck regulator.
The device integrates 100mΩ MOSFETS that provide 3A
continuous load current over a wide operating input voltage
of 4.75V to 18V. Current mode control provides fast transient
response and cycle-by-cycle current limit.
An adjustable soft-start prevents inrush current at turn-on. In
shutdown mode, the supply current drops below 1μA.
This device, available in an 8-pin SOP package, provides a
very compact system solution with minimal reliance on
external components.
Applications
Distributed Power Systems
Networking Systems
FPGA, DSP, ASIC Power Supplies
Green Electronics/ Appliances
Notebook Computers
Chipown
3A, 18V Synchronous Rectified
Step-Down Converter
Features
3A Output Current
Wide 4.75V to 18V Operating Input Range
Integrated 100mΩ Power MOSFET Switches
Output Adjustable from 0.925V to 15V
Up to 95% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output Capacitors
Fixed 370KHz Frequency
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Thermally Enhanced 8-Pin SOP Package
Package
SOP8-PP
2
3
4
8
7
6
5
Typical Application Circuit
Figure 1. Typical Application Circuit
100
90
80
70
60
50
40
30
20
10
0
0
Vout=5V
Vin=12V
Vin=18V
Vin=9V
500 1000 1500 2000 2500 3000 3500
Load(mA)
Figure 2. Typical Efficiency Curve
8/F, ChuangYuan Building No.21-1 Changjiang Road, Wuxi New Destrict Tel: +86(510)8521-7718 http://www.chipown.com.cn V2.0
1/9
1 page  
AP2953A
Application Information
Component Selection
Setting the Output Voltage
The output voltage is set using a resistive voltage divider
from the output voltage to FB (see Typical Application
circuit on page 1). The voltage divider divides the output
voltage down by the ratio:
Where VFB is the feedback voltage and VOUT is the
output voltage.
Thus the output voltage is:
R2 can be as high as 100kΩ, but a typical value is 10kΩ.
Using the typical value for R2, R1 is determined by:
For example, for a 3.3V output voltage, R2 is 10kΩ, and R1
is 26.1kΩ. Table 1 lists recommended resistance values of R1
and R2 for standard output voltages.
Chipown
voltage, fS is the switching frequency, and ΔIL is the peak-
to-peak inductor ripple current.
Choose an inductor that will not saturate under the maximum
inductor peak current. The peak inductor current can be
calculated by:
Where ILOAD is the load current.
The choice of which style inductor to use mainly depends on
the price vs. size requirements and any EMI requirements.
Optional Schottky Diode
During the transition between high-side switch and low-side
switch, the body diode of the lowside power MOSFET
conducts the inductor current. The forward voltage of this
body diode is high. An optional Schottky diode may be
paralleled between the SW pin and GND pin to improve
overall efficiency. Table 2 lists example Schottky diodes and
their Manufacturers.
Input Capacitor
Inductor
The inductor is required to supply constant current to the
output load while being driven by the switched input voltage.
A larger value inductor will result in less ripple current that
will result in lower output ripple voltage. However, the larger
value inductor will have a larger physical size, higher series
resistance, and/or lower saturation current. A good rule for
determining the inductance to use is to allow the peak-to-peak
ripple current in the inductor to be approximately 30% of the
maximum switch current limit. Also, make sure that the peak
inductor current is below the maximum switch current limit.
The inductance value can be calculated by:
Where VOUT is the output voltage, VIN is the input
The input current to the step-down converter is discontinuous,
therefore a capacitor is required to supply the AC current to the
step-down converter while maintaining the DC input voltage.
Use low ESR capacitors for the best performance. Ceramic
capacitors are preferred, but tantalum or low-ESR electrolytic
capacitors may also suffice. Choose X5R or X7R dielectrics
when using ceramic capacitors. Since the input capacitor
absorbs the input switching current it requires an adequate
ripple current rating. The RMS current in the input capacitor
can be estimated by:
The worst-case condition occurs at VIN = 2VOUT, where
ICIN = ILOAD/2. For simplification, choose the input
capacitor whose RMS current rating greater than half of the
maximum load current. The input capacitor can be electrolytic,
tantalum or ceramic. When using electrolytic or tantalum
capacitors, a small, high quality ceramic capacitor, i.e. 0.1μF,
8/F, ChuangYuan Building No.21-1 Changjiang Road, Wuxi New Destrict Tel: +86(510)8521-7718 http://www.chipown.com.cn
V2.0
5/9
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet AP2953A.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AP2953 | Synchronous Step-Down Regulator | Chipown |
| AP2953A | 18V Synchronous Rectified Step-Down Converter | Chipown |
| 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 |