|
|
PDF SC192 Data sheet ( Hoja de datos )
| Número de pieza | SC192 | |
| Descripción | Synchronous Buck Converter | |
| Fabricantes | Semtech | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de SC192 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
|
No Preview Available !
POWER MANAGEMENT
Description
The SC192 is a synchronous step-down converter with
integrated power devices designed for battery operated
systems. The internal power switches reduce system
size and cost. In addition, an efficiency of 95% can be
achieved for significant line and load ranges. The SC192
is designed for single-cell Li-Ion battery applications, but
also performs well in fixed 3.3V or 5V input circuits.
The SC192 has a flexible clocking scheme. It can be
synchronized to an external oscillator, fixed to the inter-
nal oscillator, or allowed to modulate the frequency dur-
ing light loads (PSAVE) for maximum battery life, by the
method called pulse frequency modulation (PFM). Shut-
down places the switches in a high impedance state and
turns off all control circuitry to achieve a typical quies-
cent current of 0.1μA.
Line and load regulation is to +/-0.5% of the output volt-
age. The internal MOSFET switches provide >1A peak
current to provide a DC output of at least 700mA.
Grounding the ILIM pin reduces the current limit by half.
SC192
Synchronous Buck Converter
with Integrated Power Deviceswww.DataSheet4U.com
Features
2.7V to 7V Input Range
Output Adjustable from 0.75V to Vin
Fixed Frequency or PSAVE for Maximum
Efficiency Over Wide Load Current Range
700mA Guaranteed Output Current
No Schottky Diode Required
35μA Quiescent Current
100% Duty Cycle in Dropout
95% Efficiency
Fast Transient Response
Over Temperature Protection
Space-saving Micro Lead-Frame Package
MLPD-10 3x3
Applications
Cell Phones
Cordless Phones
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
1 Li-Ion or 3 NiMH/NiCd Powered Devices
The SC192 can achieve 100% duty cycle for excellent
low dropout performance and comes in a tiny MLPD-10,
3 x 3 package having a maximum height of 1mm.
Typical Application Circuit
Vin = 2.7V to 7V
C1
C3
1
VIN
8
EN
6
ILIM
SC192
9
LX
ADJ 5
L1
2
BP
3
GND
10
PGND
7
SYNC/PWM
4
COMP
R8
C4
Vout = 0.75V to Vin
C5 R1
C6
R2
Revision 8, March 26, 2007
1
www.semtech.com
1 page  
POWER MANAGEMENT
Block Diagram
SC192
www.DataSheet4U.com
BP
ILIM V
-
Plimit
amp
+
SYNC/
PWM
OSC and slope
generation
COMP
-
PWM
comp
+
Current
amp
Control
logic
ADJ
EN
-
Error
amp
+
750mV
Nlimit
comp
V
GND
VIN
LX
PGND
© 2007 Semtech Corp.
5
www.semtech.com
5 Page 
POWER MANAGEMENT
Applications Information Cont.
PSAVE, Cout = 4.7uF, Lout = 4.7uH
SC192
www.DataSheet4U.com
PWM, Cout = 4.7uF, Lout = 4.7uH
Inductor Selection
The inductor values listed in Table 1 will work for nearly
all combinations of output current and output voltages.
After selecting 4.7uH or 10uH for the inductor value two
additional inductor parameters should be considered. The
current rating of the inductor and the DC resistance.
The DC resistance has a great impact on efficiency due
to copper losses. However, small inductors tend to have
higher DC resistance. Therefore a compromise between
size and efficiency will need to be made.
The inductor current must be chosen to prevent the in-
ductor from saturation. The most conservative approach
would be to select an inductor with a saturation current
slightly above the maximum current capability of the
SC192 which is 1.56A peak current for ILIM = Vin or
780mA for ILIM = GND.
A more accurate design of the inductor would be to rate
the inductor for the maximum output current plus the
inductor ripple current that can be calculated as follows:
IL(MAX) = IO(MAX ) + ΔIL
2
f = Switching frequency
L = Inductor Value
ΔIL= Peak-to-peak inductor ripple current
IVLO=UT
Maximum inductor
= Output voltage
current
VIN = Input voltage
COUT = Output Capacitance
IIOOUUTT(M=AX)O=utMpuatxiCmuurrmenDt C Output Current
Output Capacitor Selection
Because the SC192 has external compensation avail-
able, low ESR ceramic capacitors can be used. This elimi-
nates the need for bulky tantalum capacitors. Values for
the output capacitors in Table 1 will work for nearly all
combinations of output current and output voltages. The
equation for determining the size of the output capaci-
tor in terms of minimizing the ripple voltage is given as
follows:
ΔVO = ΔIL • ⎜⎛ 1 + ESR ⎟⎞
⎝ 8 • COUT • f
⎠
⎜⎛1- VOUT ⎟⎞
ΔIL = ⎜ VIN ⎟ •VOUT
⎜⎜⎝ L•f ⎟⎟⎠
© 2007 Semtech Corp.
Input Capacitor Selection
The input ripple current can be reduced with properly
selecting the input capacitor. Again, values for the input
capacitors in Table 1 will work for nearly all combina-
tions of input current and output voltages. The input ca-
pacitor should be rated for the maximum input ripple
current calculated as:
11 www.semtech.com
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet SC192.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| SC190 | Synchronous Buck Converter | Semtech |
| SC191 | Low Supply Ripple Synchronous Buck Conversion Regulator | Semtech |
| SC192 | Synchronous Buck Converter | Semtech |
| SC194A | 1A Synchronous Buck Converter | Semtech |
| 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 |