LT1309 Datasheet, PDF (1/8 Pages) Linear Technology – 500kHz Micropower DC/DC Converter for Flash Memory

LT1309
500kHz Micropower
DC/DC Converter
for Flash Memory
FEATURES
s _{60mA Output Current at 12V from 3V or 5V Supply}
s _{Shutdown to 9µA}
s _{VPP VALID Comparator}
s _{Up to 85% Efficiency}
s _{Switching Frequency: 500kHz (Typical)}
s _{Quiescent Current: 650µA}
s _{Low VCESAT Switch: 300mV at 0.5A (Typical)}
s _{Soft Start Reduces Supply Current Transients}
s _{Uses Low Value, Small Size,}
Surface Mount Inductors
s _{Available in 8-Lead SO Package}
APPLICATI S
s _{Flash Memory VPP Generators}
s _{Type II and III PCMCIA Card DC/DC Converters}
s _{3V to 12V, 5V to 12V Converters}
s _{Portable Computers and Instruments}
s _{Cellular Telephones}
s _{DC/DC Converter Module Replacements}
DESCRIPTIO
The LT ^®1309 is a 500kHz micropower DC/DC converter
for Flash Memory. The regulator features Burst Mode^TM
operation with a 0.5A, 300mV switch, enabling 85%
efficiency at the fixed 12V output. High frequency opera-
tion permits the use of small value, and therefore small
size, surface mount inductors and capacitors. The LT1309
comes in an 8-lead SO package allowing extremely
compact PC board layouts. These features make the
device attractive for PCMCIA cards, cellular phones and
other applications where PC board space is limited.
Quiescent current is 650µA decreasing to 9µA when the
part shuts down. The device includes a soft start feature
which limits supply current transients during turn-on.
The LT1309 contains a VPP VALID comparator with a
logic output that goes low when the output voltage is
ready to program 12V Flash Memory. This comparator
simplifies the interface to external control logic.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATI
12V, 60mA Flash Memory Programming Supply
V_IN
3.3V TO 5V
L1*
10µH
D1^† _{VPP 12V, 60mA}
V_IN
V_SW
VPP VALID VPP VALID SENSE
LT1309
+ _C1
ON/OFF
ON/OFF
PGND
SOFT
START
GND
R1
4.7µF
1M
C3
0.1µF
C2
1µF**
*MURATA ERIE LQH3C100K0YM00
** CERAMIC
†
MOTOROLA MBR0530
LT1309 • TA01
12V Output Efficiency
86
V_IN = 5V
84
82
80
V_IN = 3.3V
78
76
74
72
70
1
10
LOAD CURRENT (mA)
100
LT1309 • TA02
1