LTC3429_15 Datasheet, PDF (1/12 Pages) Linear Technology – 600mA, 500kHz Micropower Synchronous Boost Converter with Output Disconnect

LTC3429/LTC3429B
600mA, 500kHz Micropower
Synchronous Boost Converter
with Output Disconnect
FEATURES
■ _{Up to 96% Efficiency}
■ _{True Output Load Disconnect}
■ _{Inrush Current Limiting and Internal Soft-Start}
■ _{Low Voltage Start-Up: 0.85V}
■ _{Automatic Burst Mode}^® _{Operation with IQ ~ 20µA}
■ _{Continuous Switching at Light Loads (LTC3429B)}
■ _{Internal Synchronous Rectifier}
■ _{Current Mode Control with Internal Compensation}
■ _{Short-Circuit Protection}
■ _{500kHz Fixed Frequency Switching}
■ _{Input Range: 0.5V to 4.4V}
■ _{Output Range: 2.5V to 4.3V (Up to 5V with Schottky)}
■ _{Shutdown Current: <1µA}
■ _{Antiringing Control Minimizes EMI}
■ _{Tiny External Components}
■ _{Low Profile (1mm) SOT-23 Package}
U
APPLICATIO S
■ _{MP3 Players}
■ _{Digital Cameras}
■ _{LCD Bias Supplies}
■ _{Handheld Instruments}
■ _{Wireless Handsets}
■ _{GPS Receivers}
DESCRIPTIO
The LTC^®3429/LTC3429B are high efficiency synchro-
nous, fixed frequency, step-up DC/DC converters with true
output load disconnect, inrush current limiting and soft-
start in a low profile 6-lead ThinSOT^TM package. These
devices are capable of supplying 100mA from a single AA
cell input or 250mA from a 2-cell AA with a 3.3V output.
A switching frequency of 500kHz minimizes overall solu-
tion footprint by allowing the use of tiny, low profile
inductors and ceramic capacitors. Current mode PWM
control with internal compensation reduces external parts
count thereby saving critical board real estate. The LTC3429
shifts automatically to power saving Burst Mode operation
at light loads while the LTC3429B features continuous
switching at light loads. Antiringing control circuitry re-
duces EMI concerns by damping the inductor in discon-
tinuous mode.
The devices also feature low shutdown current of under
1µA. The true output disconnect feature allows the output
to be completely discharged in shutdown. It also limits the
inrush of current during start-up, minimizing surge cur-
rents seen by the input supply.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Burst Mode is a registered
trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology
Corporation.
TYPICAL APPLICATIO
+
2-CELL
AA
4.7µH
4.7µF
OFF ON
SW
V_IN V_OUT
LTC3429
SHDN FB
GND
1.02M
604k
V_OUT
3.3V
250mA
10µF
3429 F01a
Figure 1. 2-Cell to 3.3V Synchronous Boost Converter
2-Cell to 3.3V Efficiency
100
100
V_IN = 3V
90 EFFICIENCY
10
V_IN = 2.4V
80
1
70
60
50
40
0.1
V_IN = 2.4V
0.1
V_IN = 3V _0.01
POWER LOSS
0.001
1
10
100
OUTPUT CURRENT (mA)
0.0001
1000
3429 F01b
3429fa
1