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PDF SC191 Data sheet ( Hoja de datos )
| Número de pieza | SC191 | |
| Descripción | Low Supply Ripple Synchronous Buck Conversion Regulator | |
| Fabricantes | Semtech | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC191 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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POWER MANAGEMENT
Description
SC191
Low Supply Ripple Synchronous
Buck Converwswiwo.DnataRSheeegt4Uu.cloamtor
Features
The SC191 is a synchronous step-down converter with
integrated power devices and an integrated front-end
LDO regulator to minimize input supply ripple. If supply
ripple is not a concern, the front-end LDO regulator can be
bypassed externally to maximize efficiency.
The internal MOSFET switches provide peak current greater
than 550mA to achieve a DC output of at least 330mA over
the rated input voltage range, making the SC191 ideal for
single-cell Li-ion battery applications as well as fixed 3.3V
and 5V fixed input applications. The output is a fixed 1.2V
- ideal for low-voltage microprocessors. Other voltage
options are available (consult the factory for details).
Additional features include internal soft-start to limit in-
rush current, over-current protection, over-temperature
protection, and over-voltage protection.
The 1MHz switching frequency allows the use of small
surface mount capacitors and inductors, and no other
external compensation components are needed. The
device is available in a low profile (0.8mm max height)
2.3mm x 2.3mm MLPD 8-lead package, minimizing area
without compromising performance.
Less than 1mV Supply Ripple
2.7V to 5.5V Input Range
330mA Guaranteed Output Current
Fixed Frequency 1MHz Operation
No Schottky Diode Required
Over-Current Protection
Over-Voltage Protection
Over-Temperature Protection
Soft-Start
No External Compensation Required
MLPD-8, 2.3mm x 2.3mm Package
WEEE and RoHS Compliant
Applications
Cell Phones
Cordless Phones
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
WLAN Peripherals
Wireless Modules
1 Li-Ion or 3 NiMH/NiCd Powered Devices
Patent Pending
Typical Application Circuit
VIN
CIN
4.7μF
3 VIN SC191
4 EN
2 PVIN
7 PGND
8
LX
5
VOUT
BP
GND
1
6
L
4.7μH
CBP
4.7μF
COUT
4.7μF
VOUT
April 12, 2006
1 www.semtech.com
1 page  
POWER MANAGEMENT
Block Diagram
SC191
www.DataSheet4U.com
VIN 3
Voltage
References
VREF1
500mV
Plimit
Amp
LDO
Error Amp
Current
Amp
2 PVIN
Front-End
LDO
1 BP
OSC and Slope
Generator
VOUT 5
500mV
Error
Amp
EN 4
PWM
Comp
Control
Logic
VREF1
Nlimit
Comp
8 LX
7
PGND
6 GND
Pin Descriptions
Pin#
1
2
3
4
5
6
7
8
Pin Name Pin Function
Regulated output, with respect to VIN, of the front-end LDO. A 4.7μF decoupling capacitor
BP should be connected to this pin. This output is connected directly to the internal switching
MOSFETs.
PVIN Input power supply for the power devices.
VIN
EN
VOUT
Input power supply for the analog functions.
Enable (digital input): high input enables the SC191, a low disables and reduces the quiescent
current to < 1μA. In shutdown LX becomes high impedance.
Regulated output voltage and feedback for the SC191.
GND
PGND
LX
Ground: this pin should be connected directly to PGND on the user’s PCB.
Power Ground: this pin should be connected directly to GND on the user’s PCB and should
be the reference point for the input, output and BP capacitor GND connections. These ground
paths should be separate and as short as possible to minimize circuit noise.
Inductor connection to the switching MOSFETs.
© 2006 Semtech Corp.
5
www.semtech.com
5 Page 
POWER MANAGEMENT
Typical Characteristics (Cont.)
Input Voltage Ripple (FELDO Active)
VIN =3.6V, IOUT=300mA, CBP=10uF, CIN= 10uF
VOUT
5mV/DIV
VLX
2V/DIV
SC191
www.DataSheet4U.com
Input Voltage Ripple (FELDO Bypassed)
VIN =3.6V, IOUT=300mA, CBP=10uF, CIN= not fitted
VOUT
5mV/DIV
VLX
2V/DIV
400ns/Div
Input Voltage Ripple (FELDO Bypassed)
VIN =3.6V, IOUT=300mA, CBP=20uF, CIN= not fitted
VOUT
5mV/DIV
VLX
2V/DIV
400ns/Div
400ns/Div
© 2006 Semtech Corp.
11
www.semtech.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet SC191.PDF ] | |
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