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PDF LTC3250-1.5 Data sheet ( Hoja de datos )
| Número de pieza | LTC3250-1.5 | |
| Descripción | Inductorless Step-Down DC/DC Converter | |
| Fabricantes | Linear | |
| Logotipo |  |
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LTC3250-1.5/LTC3250-1.2
High Efficiency, Low Noise,
Inductorless Step-Down
DC/DC Converter
FEATURES
s 2.7V to 5.5V Input Voltage Range
s No Inductors
s Li-Ion (3.6V) to 1.5V with 81% Efficiency
s Low Noise Constant Frequency Operation
s Output Voltages: 1.5V ±4%, 1.2V ±4%
s Output Current: 250mA
s Shutdown Disconnects Load from VIN
s Low Operating Current: IQ = 35µA
s Low Shutdown Current: ISD < 1µA
s Oscillator Frequency = 1.5MHz
s Soft-Start Limits Inrush Current at Turn-On
s Short-Circuit and Overtemperature Protected
s Low Profile (1mm) SOT-23 Package
U
APPLICATIO S
s Handheld Computers
s Cellular Phones
s Digital Cameras
s Handheld Medical Instruments
s Low Power DSP Supplies
DESCRIPTIO
The LTC®3250-1.5/LTC3250-1.2 are charge pump step-
down DC/DC converters that produce a 1.5V or 1.2V
regulated output from a 2.7V to 5.5V input. The parts use
switched capacitor fractional conversion to achieve typi-
cal efficiency two times higher than that of a linear regu-
lator. No inductors are required.
A unique constant frequency architecture provides a low
noise regulated output as well as lower input noise
than conventional charge pump regulators.* High
frequency operation (fOSC = 1.5MHz) simplifies filtering
to further reduce conducted noise. The part also uses
Burst Mode® operation to improve efficiency at light loads.
Low operating current (35µA with no load, <1µA in
shutdown) and low external parts count (three small
ceramic capacitors) make the LTC3250-1.5/LTC3250-1.2
ideally suited for space constrained battery powered appli-
cations. The parts are short-circuit and overtemperature
protected, and are available in a low profile (1mm) 6-pin
ThinSOTTM package.
, LTC and LT are registered trademarks of Linear Technology Corporation
Burst Mode is a registered trademark of Linear Technology Corporation
ThinSOT is a trademark of Linear Technology Corporation.
*U.S. Patent #6, 411, 531
TYPICAL APPLICATIO
Li-Ion to 1.5V Output with Shutdown
1µF
VIN
3.2V TO 4.2V
Li-Ion
1µF
OFF ON
C– C+
VIN VOUT
LTC3250-1.5 4.7µF
SHDN GND
VOUT = 1.5V ± 4%
100mA
3250 TA1a
Efficiency vs Input Voltage
(IOUT = 100mA)
100
90
80
LTC3250-1.5
70
60
50
40
LDO
30
20
10
0
3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)
3250 TA01b
3250fa
1
1 page  
LTC3250-1.5/LTC3250-1.2
PI FU CTIO S
VIN (Pin 1): Input Supply Voltage. Bypass VIN with a ≥1µF
low ESR ceramic capacitor.
GND (Pin 2): Ground. Connect to a ground plane for best
performance.
SHDN (Pin 3): Active Low Shutdown Input. A low voltage
on SHDN disables the LTC3250-1.5/LTC3250-1.2. SHDN
must not be allowed to float.
C– (Pin 4): Flying Capacitor Negative Terminal
VOUT (Pin 5): Regulated Output Voltage. VOUT is discon-
nected from VIN during shutdown. Bypass VOUT with a
≥4.7µF low ESR ceramic capacitor (2.5µF min, ESR
< 100mΩ).
C+ (Pin 6): Flying Capacitor Positive Terminal.
BLOCK DIAGRA
SHDN 3
THERMAL
SHUTDOWN
(>160°C)
VIN 1
BURST
DETECT
CIRCUIT
LTC3250-1.5/
LTC3250-1.2
SWITCH
CONTROL
AND
SOFT-START
1.5MHz
OSCILLATOR
CHARGE
PUMP
6 C+
5 VOUT
4 C–
VREF
2
GND
3250 BD
3250fa
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5 Page 
PACKAGE DESCRIPTIO
LTC3250-1.5/LTC3250-1.2
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
0.62 0.95
MAX REF
1.22 REF
2.90 BSC
(NOTE 4)
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC 1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.20 BSC
DATUM ‘A’
0.95 BSC
0.80 – 0.90
1.00 MAX
0.30 – 0.50 REF
0.09 – 0.20
NOTE:
(NOTE 3)
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1.90 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
0.01 – 0.10
S6 TSOT-23 0302
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.
3250fa
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC3250-1.5.PDF ] | |
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