LTC3537(RevA) Просмотр технического описания (PDF) - Linear Technology
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LTC3537 Datasheet PDF : 20 Pages
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LTC3537
2.2 MHz, 600mA
Synchronous Step-Up DC/DC
Converter and 100mA LDO
FEATURES
n High Efficiency Step-Up DC/DC Converter and LDO
Step-Up
n VIN: 0.68V to 5V, VOUT: 1.5V to 5.25V
IOUT: 100mA at 3.3V, VIN >0.8V
n 2.2MHz Fixed Frequency Operation
n Synchronous Rectifier with Output Disconnect
n Burst Mode Operation (Pin Selectable)
Linear LDO Regulator
n VIN: 1.8V to 5.5V, VOUT: 0.6V to 5V
IOUT: 100mA
n 100mV Dropout Voltage at 50mA
n 24dB Ripple Rejection at fSW
Combined
n Power Good Indicators
n Low-Battery Comparator
n 30μA IQ
n Low Profile 3mm × 3mm × 0.75mm Package
APPLICATIONS
n Wireless Microphones
n Portable Medical instruments
n Noise Cancelling/Portable Headsets
n RF and Audio Power
DESCRIPTION
The LTC®3537 combines a high efficiency, 2.2MHz step-up
DC/DC converter with an idependent 100mA low dropout
regulator (LDO). The step-up converter starts from an input
voltage as low as 0.68V and contains an internal 0.4Ω
switch and a 0.6Ω synchronous rectifier that disconnects
from the output when disabled in shutdown.
A switching frequency of 2.2MHz minimizes solution
footprint by allowing the use of tiny, low profile inductors
and ceramic capacitors. The current mode PWM design
is internally compensated, reducing external parts count.
Fixed frequency switching is maintained until a light load
current is sensed, at which point Burst Mode® operation is
engaged to maximize efficiency. For low noise operation,
Burst Mode Operation can be disabled. Anti-ring circuitry
reduces EMI by damping the inductor in discontinuous
mode. Additional features include a low shutdown current
of under 1μA and thermal overload protection.
The integrated LDO regulator provides a very low noise,
programmable low dropout supply.
L, 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
ALKALINE +
0.8V
TO
1.6V
R6
665k
R5
1.0M
1μF
OFF ON
PWM BURST
2.2μH
VINB
SW VOUTB
LBI LTC3537 VINL
LBO
PGDB
FBB
PGDL
ENLDO
VOLDO
ENBST
MODE
FBL
SGND PGND
R2
1.74M
VOUTB
3.3V
4.7μF
R4
2.05M
R1 R3
1M 511k
VOLDO
3V
1μF
3537 TA01a
Efficiency and Power Loss
vs Load Current
100
1000
90
80
100
EFFICIENCY
70
60
10
50
40
POWER LOSS 1
30
20
0.1
10
0
0.01
VIN, MODE = 1.8V
0.01
0.1
1
10 100 1000
LOAD CURRENT (mA)
3537 TA01b
3537fa
1
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