LTC3402_15 Datasheet, PDF (1/16 Pages) Linear Technology – 2A, 3MHz Micropower Synchronous Boost Converter

FEATURES
■ _{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 (VOUT < 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}
U
APPLICATIO S
■ _{Cellular Telephones}
■ _{Handheld Computers}
■ _{MP3 Players}
■ _{2-Way Pagers}
■ _{GPS Receivers}
■ _{Battery Backup Supplies}
■ _{CCFL Backlights}
LTC3402
2A, 3MHz Micropower
Synchronous Boost Converter
DESCRIPTIO
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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
All Ceramic Capacitor 2-Cell to 3.3V at 1A Step-Up Converter
V_IN = 1.8V to 3V
L1
2.2μH
+
2
CELLS
C1
10μF
LTC3402
3
4
V_IN
SW
10
SHDN
7
V_OUT
2
8
MODE/SYNC FB
6
PGOOD
1
R_t
9
V_C
5
GND
R_t
30.1k
R2
909k
V_OUT
3.3V
1A
C3
470pF
R5
82k
R1
549k
C4
4.7pF
C2
44μF
(2 × 22μF)
0 = FIXED FREQ
1 = Burst Mode OPERATION
C1: TAIYO YUDEN JMK212BJ106MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: COILCRAFT: D03316P-222
3402 TA01
Efficiency
100
Burst Mode
90 OPERATION
80
1MHz
70
CONSTANT
FREQUENCY
60
50
40
30
20
10
V_IN = 2.4V WITH SCHOTTKY
0
0.1
1
10
100
I_OUT (mA)
1000
3402 TA02
3402fb
1