LT1301
Micropower High Efficiency
5V/12V Step-Up DC/DC
Converter for Flash Memory
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTION
The LT1301 is a micropower step-up DC/DC converter that
utilizes Burst Mode鈩?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 120碌A(chǔ) and a shutdown pin which
reduces supply current to 10碌A(chǔ). 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.
12V at 120mA from 5V or 3.3V Supply
Supply Voltage as Low as 1.8V
Better High Current Efficiency Than CMOS
Up to 89% Efficiency
120碌A(chǔ) Quiescent Current
Shutdown to 10碌A(chǔ)
Programmable 5V or 12V Output
Low V
CESAT
Switch: 170mV at 1A Typical
I
LIM
Pin Programs Peak Switch Current
Uses Inexpensive Surface Mount Inductors
8-Lead DIP or SOIC Package
APPLICATIONS
s
s
s
s
s
s
Flash Memory V
PP
Generator
Palmtop Computers
Portable Instruments
Bar-Code Scanners
Personal Digital Assistants
PCMCIA Cards
TYPICAL APPLICATIONS
N
5V
OR
3.3V
V
IN
SELECT
L1
33碌H
D1
Output Voltage
12V
OUTPUT
12V
V
OUT
2V/DIV
SW
SENSE
47碌F
SHUTDOWN SHDN
PGND
+
C2
I
LIM
GND
N/C
33碌F
20V
0.1碌F*
SHUTDOWN
10V/DIV
1ms/DIV
LT1301 F1
EFFICIENCY (%)
+
C1
LT1301
*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
V
IN
= 5V, V
OUT
= 12V
LOAD = 100鈩?/div>
LT1301 TAO1
Figure 1. 3.3V/5V to 12V Step-Up Converter
U
U
U
Efficiency
90
88
86
84
82
80
78
76
74
72
0
1
10
100
LOAD CURRENT (mA)
300
LT1301 TA2
V
IN
= 5V
V
IN
= 3.3V
LT1300 F2
1
next