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PDF LTC3526 Data sheet ( Hoja de datos )
| Número de pieza | LTC3526 | |
| Descripción | 500mA 1MHz Synchronous Step-Up DC/DC Converters | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC3526 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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FEATURES
LTC3526/LTC3526B
500mA 1MHz Synchronous
Step-Up DC/DC Converters
in 2mm × 2mm DFN
DESCRIPTION
n Delivers 3.3V at 100mA from a Single Alkaline/
NiMH Cell or 3.3V at 200mA from Two Cells
n VIN Start-Up Voltage: 850mV
n 1.6V to 5.25V VOUT Range
n Up to 94% Efficiency
n Output Disconnect
wwwn.Da1tMaSHhzeeFti4xUe.cdoFmrequency Operation
n VIN > VOUT Operation
n Integrated Soft-Start
n Current Mode Control with Internal Compensation
n Automatic Burst Mode® Operation with 9μA
Quiescent Current (LTC3526)
n Low Noise PWM Operation (LTC3526B)
n Internal Synchronous Rectifier
n Logic Controlled Shutdown (IQ < 1μA)
n Anti-Ringing Control
n Low Profile (2mm × 2mm × 0.75mm) DFN Package
APPLICATIONS
n Medical Instruments
n Flash-Based MP3 Players
n Noise Canceling Headphones
n Wireless Mice
n Bluetooth Headsets
The LTC®3526/LTC3526B are synchronous, fixed frequency
step-up DC/DC converters with output disconnect. Syn-
chronous rectification enables high efficiency in the low
profile 2mm × 2mm DFN package. Battery life in single
AA/AAA powered products is extended further with an
850mV start-up voltage and operation down to 500mV
once started.
A switching frequency of 1MHz minimizes solution foot-
print by allowing the use of tiny, low profile inductors and
ceramic capacitors. The current mode PWM design is
internally compensated, reducing external parts count. The
LTC3526 features automatic Burst Mode operation at light
load conditions, while the LTC3526B features continuous
switching at light loads. Anti-ringing control circuitry also
reduces EMI concerns by damping the inductor in discon-
tinuous mode. Additional features include a low shutdown
current of under 1μA and thermal shutdown.
The LTC3526/LTC3526B are housed in a 2mm × 2mm ×
0.75mm DFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
4.7μH
VIN
1.6V TO 3.2V
1μF
OFF ON
SW
VIN VOUT
LTC3526
SHDN FB
GND
1.78M
VOUT
3.3V
200mA
4.7μF
1M
3526 TA01a
LTC3526 Efficiency and Power Loss vs Load Current
100
VIN = 2.4V
90
80
EFFICIENCY
1000
100
70
60 10
50
POWER LOSS
40 1
30
20 0.1
10
0
0.01
0.01
0.1 1 10 100 1000
LOAD CURRENT (mA)
3526 TA01b
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1
1 page  
TYPICAL PERFORMANCE CHARACTERISTICS
LTC3526/LTC3526B
VFB vs Temperature
0.50
NORMALIZED TO 25°C
0.25
0
–0.25
–0.50
–0.75
www.DataSheet4U.com
–1.00
–60 –40 –20 0 20 40 60 80 100
TEMPERATURE (°C)
3526 G13
Fixed Frequency Switching
Waveform and VOUT Ripple
Start-Up Voltage vs Temperature
1.00
LOAD = 1mA
0.95
0.90
0.85
0.80
0.75
0.70
–50 –30 –10 10 30 –50
TEMPERATURE (°C)
70 90
3526 G14
Burst Mode Waveforms
Burst Mode Current vs VOUT
10.0
9.5
9.0
8.5
8.0
7.5
7.0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
VOUT (V)
3526 G15
VOUT and IIN During Soft-Start
SW PIN
2V/DIV
VOUT
10mV/DIV
AC COUPLED
VIN = 1.2V
500ns/DIV
VOUT = 3.3V AT 100mA
COUT = 10μF
SW PIN
2V/DIV
VOUT
20mV/DIV
AC COUPLED
3526 G16
INDUCTOR
CURRENT
0.2A/DIV
VIN = 1.2V
VOUT = 3.3V
COUT = 10μF
10μs/DIV
VOUT
1V/DIV
INPUT
CURRENT
0.2A/DIV
SHDN PIN
1V/DIV
3526 G17
VOUT = 3.3V
COUT = 10μF
200μs/DIV
3526 G18
Load Step Response (from Burst
Mode Operation)
VOUT
100mV/DIV
AC COUPLED
LOAD
CURRENT
50mA/DIV
VIN = 3.6V
100μs/DIV
VOUT = 5V
20mA TO 170mA STEP
COUT = 10μF
3526 G19
Load Step Response
(Fixed Frequency)
VOUT
100mV/DIV
AC COUPLED
LOAD
CURRENT
50mA/DIV
VIN = 3.6V
100μs/DIV
VOUT = 5V
50mA TO 150mA STEP
COUT = 10μF
3526 G20
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5
5 Page 
LTC3526/LTC3526B
APPLICATIONS INFORMATION
inductor current without saturating. Molded chokes and
some chip inductors usually do not have enough core
area to support the peak inductor currents of 700mA
seen on the LTC3526/LTC3526B. To minimize radiated
noise, use a shielded inductor. See Table 1 for suggested
components and suppliers.
Table 1. Recommended Inductors
VENDOR
PART/STYLE
Coilcraft
(847) 639-6400
wwww.Dwawt.acSohilcereaftt4.cUo.mcom
LPO4815
LPS4012, LPS4018
MSS5131
MSS4020
MOS6020
ME3220
DS1605, DO1608
Coiltronics
www.cooperet.com
SD10, SD12, SD14, SD18, SD20,
SD52, SD3114, SD3118
FDK
(408) 432-8331
www.fdk.com
MIP3226D4R7M, MIP3226D3R3M
MIPF2520D4R7
MIPWT3226D3R0
Murata
(714) 852-2001
www.murata.com
LQH43C
LQH32C (-53 series)
301015
Sumida
(847) 956-0666
www.sumida.com
CDRH5D18
CDRH2D14
CDRH3D16
CDRH3D11
CR43
CMD4D06-4R7MC
CMD4D06-3R3MC
Taiyo-Yuden
www.t-yuden.com
NP03SB
NR3015T
NR3012T
TDK
(847) 803-6100
www.component.tdk.com
VLP
VLF, VLCF
Toko
(408) 432-8282
www.tokoam.com
D412C
D518LC
D52LC
D62LCB
Wurth
(201) 785-8800
www.we-online.com
WE-TPC type S, M
Output and Input Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used to minimize the output voltage ripple. Multilayer
ceramic capacitors are an excellent choice as they have
extremely low ESR and are available in small footprints.
A 4.7μF to 10μF output capacitor is sufficient for most
applications. Larger values up to 22μF may be used to
obtain extremely low output voltage ripple and improve
transient response. X5R and X7R dielectric materials are
preferred for their ability to maintain capacitance over
wide voltage and temperature ranges. Y5V types should
not be used.
The internal loop compensation of the LTC3526 is designed
to be stable with output capacitor values of 4.7μF or greater
(without the need for any external series resistor). Although
ceramic capacitors are recommended, low ESR tantalum
capacitors may be used as well.
A small ceramic capacitor in parallel with a larger tantalum
capacitor may be used in demanding applications that have
large load transients. Another method of improving the
transient response is to add a small feed-forward capacitor
across the top resistor of the feedback divider (from VOUT
to FB). A typical value of 22pF will generally suffice.
Low ESR input capacitors reduce input switching noise
and reduce the peak current drawn from the battery. It
follows that ceramic capacitors are also a good choice
for input decoupling and should be located as close as
possible to the device. A 2.2μF input capacitor is sufficient
for most applications, although larger values may be
used without limitations. Table 2 shows a list of several
ceramic capacitor manufacturers. Consult the manufactur-
ers directly for detailed information on their selection of
ceramic capacitors.
Table 2. Capacitor Vendor Information
SUPPLIER
PHONE
WEBSITE
AVX
(803) 448-9411
www.avxcorp.com
Murata
(714) 852-2001
www.murata.com
Taiyo-Yuden (408) 573-4150
www.t-yuden.com
TDK
(847) 803-6100
www.component.tdk.com
Samsung
(408) 544-5200
www.sem.samsung.com
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11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC3526.PDF ] | |
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