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PDF LTC3252 Data sheet ( Hoja de datos )
| Número de pieza | LTC3252 | |
| Descripción | Inductorless Step-Down DC/DC Converter | |
| Fabricantes | Linear | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC3252 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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FEATURES
s 2.7V to 5.5V Input Voltage Range
s No Inductors
s Typical Efficiency 50% Higher than LDOs
s Spread Spectrum Operation
s Low Input and Output Noise
s Shutdown Disconnects Load from VIN
s Dual Adjustable Independent Outputs
(Range: 0.9V to 1.6V)
s Output Current: 250mA Each Output
s Low Operating Current: IIN = 60µA Typ
(35µA with One Output Enabled)
s Low Shutdown Current: IIN = 0.01µA Typ
s Soft-Start Limits Inrush Current at Turn On
s Short Circuit and Over Temperature Protected
s Available in 4mm × 3mm 12-Pin DFN Package
U
APPLICATIO S
s Handheld Electronic Devices
s Cellular Phones
s Low Voltage Logic Supplies
s DSP Power Supplies
s 3.3V to 1.5V Conversion
LTC3252
Dual, Low Noise,
Inductorless Step-Down
DC/DC Converter
DESCRIPTIO
The LTC®3252 is a switched capacitor step-down DC/DC
converter that produces two adjustable regulated outputs
from a single 2.7V to 5.5V input. The part uses switched
capacitor fractional conversion to achieve a typical effi-
ciency increase of 50% over that of a linear regulator. No
inductors are required.
A unique constant frequency, spread spectrum architec-
ture provides a very low noise regulated output as well as
low noise at the input. The part also has Burst Mode®
operation to provide high efficiency at low output currents,
as well as ultralow current shutdown.
Low operating currents (60µA with both outputs enabled,
35µA with one output enabled) and low external parts
count make the LTC3252 ideally suited for space-con-
strained battery-powered applications. The part is short-
circuit and overtemperature protected and is available in a
tiny 4mm × 3mm 12-pin DFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
1.5V and 1.2V Output Voltages with Shutdown
1-CELL
Li-ION
OR 3-CELL
NiMH
OFF ON
OFF ON
4.7µF
2
11
3
4
1µF 6
10
1µF 8
7
5
EN1 OUT1
EN2
1
VIN FB1
C1 + LTC3252
C1–
C2+
9
OUT2
C2–
12
GND FB2
470k
510k
261k
510k
VOUT = 1.5V
IOUT ≤ 250mA
4.7µF
VOUT = 1.2V
IOUT ≤ 250mA
4.7µF
3252 TA01
1.5V/1.2V Efficiency vs Input Voltage
100
90
IOUT (1.5V) = 100mA
IOUT (1.2V) = 100mA
80
LTC3252-1.5V
70
60 LTC3252-1.2V
50
40
LDO-1.5V
30
20 LDO-1.2V
10
0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
VIN (V)
3252 TA01a
3252f
1
1 page  
LTC3252
PI FU CTIO S
C2– (Pin 8): Flying Capacitor 2 Negative Terminal (C2).
OUT2 (Pin 9): Regulated Output Voltage 2. OUT2 is
disconnected from VIN when in shutdown. Bypass OUT2
with a low ESR ceramic capacitor to GND (CO2). See
Output Capacitor Selection section for size requirements.
C2+ (Pin 10): Flying Capacitor 2 Positive Terminal (C2).
EN2 (Pin 11): Input Enable Pin 2. When EN2 is high, OUT2
is enabled. When EN2 is low OUT2 is shut down.
FB2 (Pin 12): Feedback Input Pin 2. An output divider
should be connected from OUT2 to FB2 to program the
output voltage.
WW
SI PLIFIED BLOCK DIGRAM
OVERTEMPERATURE
VIN 3
EN1 EN2
2 11
SWITCH
CONTROL
BURST
DETECT
CIRCUIT
–
+
–
+
SPREAD SPECTRUM
OSCILLATOR
CHARGE
PUMP 1
4 C1+
5 OUT1
6 C1–
1 FB1
CHARGE
PUMP 2
10 C2+
9 OUT2
8 C2–
12 FB2
7
GND
3252 SBD
3252f
5
5 Page 
TYPICAL APPLICATIO
Li-Ion to 1.5V/1.2V Outputs
Li-ION
OUT1
1.2V
250mA
4.7µF
4.7µF
261k
OFF ON
1µF
3
VIN
2
EN1
11
EN2 OFF ON
9
OUT2
5
OUT1
C2+ 10
4
LTC3252
C1+ C2–
8
1µF
6 C1–
FB2 12
1 FB1
GND 7
510k
470k
510k
OUT2
1.5V
250mA
4.7µF
3252 TA02
LTC3252
PACKAGE DESCRIPTIO
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695)
0.58 ±0.05
3.40 ±0.05
1.70 ±0.05
2.24 ±0.05 (2 SIDES)
PACKAGE OUTLINE
0.25 ± 0.05
0.50
BSC
3.30 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
4.00 ±0.10
(2 SIDES)
R = 0.20
TYP
R = 0.115
7 TYP
0.38 ± 0.10
12
PIN 1
TOP MARK
3.00 ±0.10 1.70 ± 0.10
(2 SIDES) (2 SIDES)
0.200 REF
0.75 ±0.05
0.00 – 0.05
61
0.25 ± 0.05
0.50
BSC
3.30 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE A VARIATION OF VERSION
(WGED) IN JEDEC PACKAGE OUTLINE M0-229
2. ALL DIMENSIONS ARE IN MILLIMETERS
3. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
4. EXPOSED PAD SHALL BE SOLDER PLATED
PIN 1
NOTCH
(UE12/DE12) DFN 0802
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
3252f
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC3252.PDF ] | |
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