LT1301 Datasheet, PDF (1/12 Pages) Linear Technology – Micropower High Efficiency 5V/12V Step-Up DC/DC Converter for Flash Memory

LT1301
Micropower High Efficiency
5V/12V Step-Up DC/DC
Converter for Flash Memory
FEATURES
s _{12V at 120mA from 5V or 3.3V Supply}
s _{Supply Voltage as Low as 1.8V}
s _{Better High Current Efficiency Than CMOS}
s _{Up to 89% Efficiency}
s _{120µA Quiescent Current}
s _{Shutdown to 10µA}
s _{Programmable 5V or 12V Output}
s _{Low VCESAT Switch: 170mV at 1A Typical}
s _{ILIM Pin Programs Peak Switch Current}
s _{Uses Inexpensive Surface Mount Inductors}
s _{8-Lead DIP or SOUIC Package}
APPLICATIONS
s _{Flash Memory VPP Generator}
s _{Palmtop Computers}
s _{Portable Instruments}
s _{Bar-Code Scanners}
s _{Personal Digital Assistants}
s _{PCMCIA Cards}
DESCRIPTION
The LT1301 is a micropower step-up DC/DC converter that
utilizes Burst Mode™ operation. The device can deliver 5V
or 12V from a two-cell battery input. It features program-
mable 5V or 12V output via a logic-controlled input, no-
load quiescent current of 120µA and a shutdown pin which
reduces supply current to 10µA. The on-chip power switch
has a low 170mV saturation voltage at a switch current of
1A, a four-fold reduction over prior designs. A 155kHz
internal oscillator allows the use of extremely small sur-
face mount inductors and capacitors. Operation is guaran-
teed at 1.8V input. This allows more energy to be extracted
from the battery, increasing operating life. The I_LIM pin can
be used for soft start or to program peak switch current
with a single resistor allowing the use of even smaller
inductors in lighter load applications. The LT1301 is
available in an 8-lead SOIC package, minimizing board
space requirements. For a selectable 3.3V/5V step-up
converter, please see the LT1300. For higher output
power, see the LT1302.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIONS N
5V
OR
3.3V
+ _C1
47µF
L1
33µH
D1
V_IN
SELECT
SW
SENSE
LT1301
SHUTDOWN SHDN
PGND
I_LIM N/C
GND
*REQUIRED FOR 5V OUTPUT
L1 = COILCRAFT DO3316-333
OR SUMIDA CD73-330KC
D1 = 1N5817 OR MOTOROLA
MBRS130LT3
C1 = AVX TPSD476M016R0100
OR SANYO OS-CON 165A47M
C2 = AVX TPSD336M020R0100
OR SANYO OS-CON 205A33M
12V
OUTPUT
12V
V_OUT
2V/DIV
Output Voltage
+ C2
33µF
20V
0.1µF*
LT1301 F1
SHUTDOWN
10V/DIV
V_IN = 5V, V_OUT = 12V
LOAD = 100Ω
1ms/DIV
Figure 1. 3.3V/5V to 12V Step-Up Converter
LT1301 TAO1
Efficiency
90
88
86
84
82
80
78
76
74
72
0
1
V_IN = 5V
V_IN = 3.3V
10
100 300
LOAD CURRENT (mA)
LT1301 TA2
LT1300 F2
1