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PDF SC196 Data sheet ( Hoja de datos )
| Número de pieza | SC196 | |
| Descripción | 1.5A Synchronous Buck Converter | |
| Fabricantes | Semtech | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC196 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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POWER MANAGEMENT
Description
The SC196 is a synchronous step-down converter with
integrated power devices designed for use in applications
using a single-cell Li-ion battery. Its wide input voltage
range also makes it suitable for use in systems with fixed
3.3V or 5V supply rails available. The switching frequency is
nominally set to 1MHz, allowing the use of small inductors
and capacitors. The current rating of the internal MOSFET
switches allows a DC output current of 1.5A.
The output voltage is set by connecting a resistor divider
from the filter inductor to the feedback pin. See the
SC196A for pin-programmable output voltages.
The SC196 has a flexible clocking methodology that
allows it to be synchronized to an external oscillator or
controlled by the internal oscillator. The device operates
in either forced PWM mode or in PSAVE mode. If PSAVE
mode is enabled, the part will automatically enter PFM at
light loads to maintain maximum efficiency across the full
load range.
For noise sensitive applications, PSAVE mode can be
disabled by synchronizing to an external oscillator or
pulling the SYNC/PWM pin high. Shutdown turns off all
the control circuitry to achieve a typical shutdown current
of 0.1μA.
SC196
1.5A Synchronous Buck Converter
with Integrated Power Deviceswww.DataSheet4U.com
Features
Up to 95% efficiency
VOUT adjustable from less than 0.8V to VIN
Output current — 1.5A
Input range — 2.5V to 5.5V
Quiescent current — 17μA
Fixed 1MHz frequency or 750kHz to 1.25MHz
synchronized operation
PSAVE operation to maximize efficiency at light loads
Shutdown current <1μA
Fast transient response
100% duty cycle in dropout
Soft-start
Over-temperature and short-circuit protection
Lead-free package — MLPD10-UT, 3 x 3 x 0.6 mm
Applications
Cell phones
Wireless communication chipset power
Personal media players
Microprocessor/DSP core/IO power
PDAs and handheld computers
WLAN peripherals
USB powered modems
1 Li-Ion or 3 NiMH/NiCd powered devices
Typical Application Circuit
VIN
2.5V to 5.5V
CIN
10μF
VIN SC196
LX
PVIN
VOUT
MODE
ADJ
EN
SYNC/PWM
PGND
GND
L1
4.7μH
RFB1
RFB2
VOUT
<0.8V to VIN
1.5A
CFB1
10pF
COUT
22μF
February 8, 2007
1 www.semtech.com
1 page  
SC196
POWER MANAGEMENT
Pin Descriptions
www.DPatRaSEheLeItM4U.IcNomARY
Pin #
1
2
Pin Name
PVIN
VIN
Pin Function
Input supply voltage connection to switching FETs — connect the input capacitor between this
pin and PGND directly.
Input supply voltage for control circuits
3
SYNC/PWM
Oscillator synchronization input. Tie to VIN for forced PWM mode or GND to allow the part to
enter PSAVE mode at light loads. Apply an external clock signal for frequency synchronization.
4
EN
Enable digital input; a high input enables the SC196, a low disables and reduces quiescent cur-
rent to less than 1μA. In shutdown, LX becomes high impedance.
5
VOUT
Regulated output voltage sense pin — connect to the output capacitor allowing sensing of the
output voltage.
6
ADJ
Output Voltage Adjust and feedback compensation pin - connect resistor divider between this
pin and GND to set the desired output voltage level.
7 MODE MODE select pin — MODE = VIN to select 100% duty cycle function, MODE = GND to disable
this function.
8
GND
Ground
9 PGND Power Ground
10 LX Inductor connection to the switching FETs
T
THERMAL Pad for heatsinking purposes — not connected internally. Connects to ground plane using
PAD
multiple vias.
© 2007 Semtech Corp.
5
www.semtech.com
5 Page 
SC196
POWER MANAGEMENT
www.DPatRaSEheLeItM4U.IcNomARY
Applications Information (Cont.)
PCB Layout Considerations
Poor layout can degrade the performance of the DC-DC
converter and can contribute to EMI problems, ground
bounce and resistive voltage losses. Poor regulation and
instability can result.
A few simple design rules can be implemented to ensure
good layout:
1. Place the inductor and filter capacitors as close to the
device as possible and use short wide traces between
the power components.
2. Route the output voltage feedback path away from the
inductor and LX node to minimize noise and magnetic
interference. Keep RFB1 and RFB2 close to the ADJ pin
to avoid noise pickup.
3. Maximize ground metal on the component side to
improve the return connection and thermal dissipation.
Separation between the LX node and GND should be
maintained to avoid coupling of switching noise to the
ground plane.
4. Use a ground plane with several vias connecting to
the component side ground to further reduce noise
interference on sensitive circuit nodes.
GND
LOUT
VIN CIN
LX
SYNC/PWM
EN
MODE
GND
SC196
COUT
RFB2
CFB1
RFB1
VOUT
GND
© 2007 Semtech Corp.
11
www.semtech.com
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet SC196.PDF ] | |
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