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PDF SC194B Data sheet ( Hoja de datos )
| Número de pieza | SC194B | |
| Descripción | Selectable 3.6V/3.3V/3.0V/2.5V 1A Synchronous Buck Converter | |
| Fabricantes | Semtech | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC194B (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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POWER MANAGEMENT
Description
The SC194B is a synchronous step-down converter with
integrated power devices. Four selectable output voltages
suitable for portable device interface, memory function
blocks, and 5V to 3.3V voltage conversion are available.
Automatic selection of Power Save Mode (PSAVE) is
supported which enhances efficiency. A 100% duty cycle
mode allows operation for input voltages close to the
required output voltage.
The need for external components is minimized by
providing internal feedback compensation, and allowing
selection of the required output voltage by hard wiring VID
code inputs. The maximum current rating of the internal
MOSFET switches allows a DC output current of 1A.
SC194B
Selectable 3.6V/3.3V/3.0V/2.5V
1A Synchronous Bwuwwc.DkataCShoeent4vU.ceormter
Features
Up to 95% efficiency
PSAVE operation to maximize efficiency
Output current — 1A
Input range — 2.7V to 5.5V
Four selectable output voltages
Quiescent current — 17μA in PSAVE
Dynamic voltage positioning capability
Fixed 1MHz frequency or 750kHz to 1.25MHz syn-
chronized operation
Current mode operation for excellent line and load
transient response
100% duty cycle in dropout
Soft-start
Over-temperature and short-circuit protection
Lead-free package — 3mm x 3mm MLPD
The switching frequency is nominally set to 1MHz, allowing
the use of small inductors and capacitors. A flexible
clocking scheme is used that allows synchronization to an
external oscillator or control by the internal oscillator.
The device can operate in either forced PWM mode or
in PSAVE mode. If PSAVE mode is enabled the part will
automatically enter PSAVE 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.
Applications
PDA
Pocket PC and Smart Phones
USB Powered Modems
CPUs and DSPs
PC Cards and Notebooks
xDSL Applications
Standard 5-V to 3.3-V Conversion
Typical Application Circuit
VIN
3.6V to 5.5V
CIN
10μF
SC194B
VIN LX
EN
SYNC/PWM
VOUT
VID0
VID1
PGND
MODE
GND
L1
4.7μH
VOUT
3.3V
1A
COUT
22μF
August 24, 2006
1 www.semtech.com
1 page  
SC194B
POWER MANAGEMENT
Pin Descriptions
www.DataSheet4U.com
Pin #
1
2
Pin Name Pin Function
VIN Input power supply voltage
MODE
MODE select pin where MODE = VIN to select 100% duty cycle function and MODE = GND to
disable
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 SC194B, a low disables and reduces quiescent
current to less than 1μA. In shutdown, LX becomes high impedance.
5 VOUT Regulated output voltage and feedback for SC194B
Logic level bit 0 is used in conjunction with VID1 to set the output voltage. Connect high or low
6
VID0
as required to select the desired output voltage. If not connected, the output voltage will be
indeterminate.
Logic level bit 1 is used in conjunction with VID0 to set the output voltage. Connect high or low
7
VID1
as required to select the desired output voltage. If not connected, the output voltage will be
indeterminate.
8
GND
Ground
9 PGND Power Ground
10 LX Inductor connection to the switching FETs
T
THERMAL Pad is for heatsinking purposes — not connected internally. Connect exposed pad to ground
PAD
plane using multiple vias.
© 2006 Semtech Corp.
5
www.semtech.com
5 Page 
POWER MANAGEMENT
Typical Characteristics
Efficiency vs. Load Current VOUT = 3.6V
100
VIN=3.9V, PSAVE
90
80 VIN=4.2V, PSAVE
70 VIN=5.0V, PSAVE
60
VIN=3.9V, PWM
50
40
VIN=5.0V, PWM
30
20 VIN=4.2V, PWM
10
0
0.0001
0.001
0.01
0.1
1
10
IOUT (A)
Efficiency vs. Load Current VOUT = 3.0V
100
VIN=3.6V, PSAVE
90
80
VIN=4.2V, PSAVE
70
VIN=5.0V, PSAVE
60
50
VIN=5.0V, PWM
40
VIN=3.6V, PWM
30
20
VIN=4.2V, PWM
10
0
0.0001
0.001
0.01
0.1
IOUT (A)
1
10
Efficiency vs. Input Voltage VOUT = 3.3V
100
VOUT=3.3V,PSAVE
95 VOUT=3.3V,PWM
90
VOUT=2.5V,PWM
85
VOUT=2.5V,PSAVE
80
75
70
2.5
3 3.5 4 4.5 5 5.5
Vin (V)
IOUT=500 mA(PWM)/50 mA(PSAVE)
6
SC194B
www.DataSheet4U.com
Efficiency vs. Load Current VOUT = 3.3V
100
VIN=3.9V, PSAVE
90
VIN=4.2V, PSAVE
80
VIN=5.0V, PSAVE
70
60
50
VIN=3.9V, PWM
40
VIN=5.0V, PWM
30
VIN=4.2V, PWM
20
10
0
0.0001
0.001
0.01
0.1
1
10
IOUT (A)
Efficiency vs. Load Current VOUT = 2.5V
100
VIN=3.3V, PSAVE
90
80
VIN=4.2V, PSAVE
70
VIN=5.0V, PSAVE
60
50
VIN=3.3V, PWM
40
VIN=5.0V, PWM
30
VIN=4.2V, PWM
20
10
0
0.0001
0.001
0.01 0.1
IOUT (A)
1
10
PWM to PSAVE Hysteresis
95
PSAVE
Entry
94 IOUT
Decreasing
93
92 PWM
Mode
91
PSAVE
EXIT
IOUT
Increasing
90
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
IOUT (A)
© 2006 Semtech Corp.
11
www.semtech.com
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet SC194B.PDF ] | |
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