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PDF LTC3423 Data sheet ( Hoja de datos )
| Número de pieza | LTC3423 | |
| Descripción | (LTC3423 / LTC3424) Low Output Voltage 3MHz Micropower Synchronous Boost Converters | |
| Fabricantes | Linear Integrated | |
| Logotipo |  |
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LTC3423/LTC3424
FEATURES
s 1.5V to 5.5V Adjustable Output Voltage
s Synchronous Rectification: Up to 95% Efficiency
s 1A Switch Current (LTC3423) or
2A Switch Current (LTC3424)
s Fixed Frequency Operation Up to 3MHz
s Wide Input Range: 0.5V to 5.5V (Operating)
s Very Low Quiescent Current: 38µA (Burst Mode®
Operation)
s No External Schottky Diode Required
s Synchronizable Switching Frequency
s Burst Mode Enable Control
s OPTI-LOOP® Compensation
s Very Low Shutdown Current: < 1µA
s Small 10-Pin MSOP Package
U
APPLICATIO S
s Pagers
s Handheld Instruments
s Cordless Phones
s Wireless Handsets
s GPS Receivers
s Battery Backup
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
Low Output Voltage,
3MHz Micropower Synchronous
Boost Converters
DESCRIPTIO
The LTC®3423 and LTC3424 are high efficiency, fixed
frequency, step-up DC/DC converters that can regulate
output voltages as low as 1.5V from a single cell. An
applied voltage of at least 2.7V to the VDD pin is required
to power the internal control circuitry.
The devices include a 0.16Ω N-channel MOSFET switch
and a 0.21Ω P-channel synchronous rectifier. The LTC3423
is intended for applications requiring less than 0.75W of
output power and the LTC3424 for 1.5W or less. Switching
frequencies up to 3MHz are programmed with an external
timing resistor and the oscillator can be synchronized to
an external clock.
Quiescent current is only 38µA in Burst Mode operation,
maximizing battery life in portable applications. Burst
Mode operation is user controlled and can be enabled by
driving the MODE/SYNC pin high. If the MODE/SYNC pin
has either a clock or is driven low then the operation is at
constant fixed frequency.
Other features include a 1µA shutdown, thermal shutdown
and current limit. The LTC3423 and LTC3424 are available
in the 10-lead MSOP package. For applications requiring
an output voltage greater than 2.6V, the LTC3401 and
LTC3402 are recommended without the need of a separate
voltage for the VDD pin.
TYPICAL APPLICATIO
1-Cell to 1.8V at 600mA Step-Up Converter
VDD
C1
2.2µF
VDD = 2.7V TO 5.5V
VIN = 0.9V TO 1.5V
L1
2.2µH
+
1
– CELL
C2
10µF
LTC3424
64
VDD SW
10
SHDN
7
VOUT
3
VIN
8
FB
29
MODE/SYNC VC
1
Rt
5
GND
Rt
30.1k
R1
110k
VOUT
1.8V
600mA
C4
470pF
RC
82k
R2
C5 249k
4.7pF
C3
44µF
(2× 22µF)
0 = FIXED FREQ
1 = Burst Mode OPERATION
C1: TAIYO YUDEN JMK212BJ225MG
C2: TAIYO YUDEN JMK212BJ106MM
C3: TAIYO YUDEN JMK325BJ226MM
L1: SUMIDA CD43-2R2M
3423/24 TA01
Efficiency
100
90
80
70
60
50
40
30
20
10
0
0.1
VIN = 1.5V
Burst Mode
OPERATION
VIN = 1.2V
VIN = 0.9V
VDD = 3.3V
VOUT = 1.8V
WITH MBRM120T3 SCHOTTKY
1 10 100
OUTPUT CURRENT (mA)
1000
3223/24 TA02
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TYPICAL PERFOR A CE CHARACTERISTICS
LTC3423/LTC3424
Shutdown Threshold
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
–55
–15 25
65
TEMPERATURE (°C)
105 125
3423/24 G13
Burst Mode Operation Current
44
42
40
38
36
34
32
30
–55
–15 25
65
TEMPERATURE (°C)
105 125
3423/24 G14
PI FU CTIO S
Rt (Pin 1): Timing Resistor to Program the Oscillator
Frequency.
fOSC
=
3 •1010
Rt
Hz
MODE/SYNC (Pin 2): Burst Mode Select and Oscillator
Synchronization.
MODE/SYNC = High. Enable Burst Mode operation. The
inductor peak inductor current will be 400mA and
return to zero current on each cycle. During Burst Mode
operation the operation is variable frequency, providing
a significant efficiency improvement at light loads. It is
recommended the Burst Mode operation only be en-
tered once the part has started up.
MODE/SYNC = Low. Disable Burst Mode operation and
maintain low noise, constant frequency operation.
MODE/SYNC = External CLK. Synchronization of the
internal oscillator and Burst Mode operation disable. A
clock pulse width of 100ns to 2µs is required to
synchronize.
VIN (Pin 3): Voltage Sense for Internal Circuitry.
SW (Pin 4): Switch Pin. Connect inductor and optional
Schottky diode here. Minimize trace length to keep EMI
down.
GND (Pin 5): Signal and Power Ground for the IC.
VDD (Pin 6): Power Source for the IC. Typically derived
from a higher voltage power converter. Requires an input
of 2.7V to 5.5V. A 2.2µF ceramic bypass capacitor is
recommended as close to the pins as possible.
VOUT (Pin 7): Output of the Synchronous Rectifier.
FB (Pin 8): Feedback Pin. Connect resistor divider tap
here. The output voltage can be adjusted from 1.5V to
5.5V. The feedback reference voltage is typically 1.25V.
VC (Pin 9): Error Amp Output. A frequency compensation
network is connected to this pin to compensate the loop.
See the section “Compensating the Feedback Loop” for
guidelines.
SHDN (Pin 10): Shutdown. Grounding this pin shuts down
the IC. Tie to >1V to enable (VDD or digital gate output).
During shutdown the output voltage will hold up to VIN
minus a diode drop due to the body diode of the PMOS
synchronous switch. If the application requires a com-
plete disconnect during shutdown then refer to section
“Output Disconnect”.
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LTC3423/LTC3424
TYPICAL APPLICATIO
Single Cell to 1.8V at 300mA, 1.8mm High
VDD
IN
C1
2.2µF
VDD = 2.7V TO 5.5V
VIN = 0.9V TO 1.5V
+
1
– CELL
C2
4.7µF
L1
4.7µH
LTC3423
64
VDD SW
10
SHDN
7
VOUT
3
VIN
8
FB
29
MODE/SYNC VC
1
Rt
GND 5
Rt fOSC = 1MHz
30.1k
D1
C4
470pF
RC
82k
R1
110k
R2
C5 249k
4.7pF
VOUT
1.8V
300mA
C3
22µF
0 = FIXED FREQ
1 = Burst Mode OPERATION
C1: TAIYO YUDEN JMK212BJ225MG
C2: TAIYO YUDEN JMK212BJ475MM
C3: TAIYO YUDEN JMK325BJ226MM
D1: ON SEMICONDUCTOR MBRM120T3
L1: SUMIDA CDRH3D16-4R7M
3423/24 TA04
PACKAGE DESCRIPTIO
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
3.2 – 3.45
(.126 – .136)
3.05 ± 0.38
(.0120 ± .0015)
TYP
0.50
(.0197)
BSC
RECOMMENDED SOLDER PAD LAYOUT
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
10 9 8 7 6
0.497 ± 0.076
(.0196 ± .003)
REF
0.254
(.010)
DETAIL “A”
0° – 6° TYP
4.88 ± 0.10
(.192 ± .004)
3.00 ± 0.102
(.118 ± .004)
NOTE 4
GAUGE PLANE
12345
0.18
(.007)
0.53 ± 0.01
(.021 ± .006)
DETAIL “A”
1.10
(.043)
MAX
0.86
(.034)
REF
SEATING
PLANE 0.17 – 0.27
(.007 – .011)
0.50
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
(.0197)
TYP
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.13 ± 0.05
(.005 ± .002)
MSOP (MS) 1001
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.
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11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC3423.PDF ] | |
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