Datasheet

LTC3429/LTC3429B
1
3429fa
MP3 Players
Digital Cameras
LCD Bias Supplies
Handheld Instruments
Wireless Handsets
GPS Receivers
600mA, 500kHz Micropower
Synchronous Boost Converter
with Output Disconnect
Figure 1. 2-Cell to 3.3V Synchronous Boost Converter
SW
4.7µH
V
OUT
LTC3429
FB
V
IN
SHDN
3429 F01a
1.02M
604k
10µF
4.7µF
2-CELL
AA
+
V
OUT
3.3V
250mA
GND
OFF
ON
2-Cell to 3.3V Efficiency
OUTPUT CURRENT (mA)
60
EFFICIENCY (%)
80
100
50
70
90
0.1 10 100 1000
3429 F01b
40
1
V
IN
= 3V
V
IN
= 3V
V
IN
= 2.4V
V
IN
= 2.4V
0.01
POWER LOSS (W)
1
100
0.001
0.1
10
0.0001
EFFICIENCY
POWER LOSS
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 I
Q
~ 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
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
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.

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