1
LTC3402
3402fb
2A, 3MHz Micropower
Synchronous Boost Converter
The LTC
®
3402 is a high efficiency, fixed frequency, step-
up DC/DC converter that operates from an input voltage
below 1V. The device includes a 0.16Ω N-channel MOSFET
switch and a 0.18Ω P-channel synchronous rectifier.
Switching frequencies up to 3MHz are programmed with
an external timing resistor and the oscillator can be
synchronized to an external clock. An external Schottky
diode is optional but will slightly improve efficiency.
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 fixed frequency
switching is enabled.
Other features include a 1μA shutdown, antiringing con-
trol, open-drain power good output, thermal shutdown
and current limit. The LTC3402 is available in the 10-lead
thermally enhanced MSOP package. Lower current appli-
cations should use the 1A rated LTC3401 synchronous
boost converter. Applications that require V
OUT
< 2.6V
should use the LTC3424.
All Ceramic Capacitor 2-Cell to 3.3V at 1A Step-Up Converter
■
Cellular Telephones
■
Handheld Computers
■
MP3 Players
■
2-Way Pagers
■
GPS Receivers
■
Battery Backup Supplies
■
CCFL Backlights
■
Synchronous Rectification: Up to 97% Efficiency
■
2A Switch Current Rating
■
Fixed Frequency Operation Up to 3MHz
■
Wide Input Range: 0.5V to 5V
■
Very Low Quiescent Current: 38μA (Burst Mode
®
Operation)
■
2.6V to 5.5V Adjustable Output Voltage
■
0.85V (Typ) Start-Up Voltage
■
No External Schottky Diode Required (V
OUT
< 4.3V)
■
Synchronizable Switching Frequency
■
Burst Mode Enable Control
■
Antiringing Control Reduces Switching Noise
■
PGOOD Output
■
OPTI-LOOP
®
Compensation
■
Very Low Shutdown Current: <1μA
■
Small 10-Pin MSOP Package
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
I
OUT
(mA)
0.1
0
EFFICIENCY (%)
10
30
40
50
100
70
3402 TA02
20
80
90
60
110
100
1000
Burst Mode
OPERATION
1MHz
CONSTANT
FREQUENCY
V
IN
= 2.4V WITH SCHOTTKY
Efficiency
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
3
10
2
6
1
3402 TA01
LTC3402
V
IN
SHDN
MODE/SYNC
PGOOD
R
t
SW
V
OUT
FB
V
C
GND
4
7
8
9
5
C3
470pF
C4
4.7pF
2
CELLS
C1
10μF
R5
82k
R
t
30.1k
R2
909k
R1
549k
V
OUT
3.3V
1A
L1
2.2μH
C2
44μF
(2 × 22μF)
C1: TAIYO YUDEN JMK212BJ106MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: COILCRAFT: D03316P-222
V
IN
= 1.8V to 3V
0 = FIXED FREQ
1 = Burst Mode OPERATION
+
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.