Datasheet
LT1109
2
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Quiescent Current Switch Off ● 320 550 µA
Minimum Start-Up Voltage 1.6 V
at V
OUT
Pin (Z Package)
V
IN
Input Voltage (N8, S8 Package) ● 3V
Comparative Trip Point Voltage LT1109 ● 1.20 1.25 1.30 V
V
OUT
Output Voltage LT1109-5; 3V ≤ V
IN
≤ 5V ● 4.75 5.00 5.25 V
LT1109-12; 3V ≤ V
IN
≤ 12V ● 11.52 12.00 12.55 V
Comparator Hysteresis LT1109 ● 8 12.5 mV
Output Voltage Ripple LT1109-5 ● 25 50 mV
LT1109-12
● 60 120 mV
f
OSC
Oscillator Frequency 100 120 140 kHz
● 90 150 kHz
t
ON
Switch ON Time 3.3 4.2 5.3 µs
● 3.0 5.5 µs
DC Duty Cycle Full Load ● 45 50 60 %
V
CESAT
Switch Saturation Voltage I
SW
= 500mA 0.4 0.7 V
LT1109-5: V
IN
= 3V; LT1109-12: V
IN
= 5V ● 0.5 0.8 V
T
A
= 25°C, V
IN
= 3V (LT1109CN8, LT1109CS8), unless otherwise specified.
E
LECTR
IC
AL C CHARA TERIST
ICS
WU
U
PACKAGE
/
O
RDER I FOR ATIO
1
2
3
4
8
7
6
5
TOP VIEW
VIN
NC
SW
GND
SENSE
SHUTDOWN
NC
NC
N8 PACKAGE
8-LEAD PLASTIC DIP
LT1109 • PO102
1
2
3
4
8
7
6
5
TOP VIEW
SENSE
SHUTDOWN
NC
NC
V
IN
NC
SW
GND
S8 PACKAGE
8-LEAD PLASTIC SOIC
LT1109 • PO103
T
JMAX
= 100°C, θ
JA
= 130°C/W
T
JMAX
= 100°C, θ
JA
= 150°C/W
T
JMAX
= 100°C, θ
JA
= 160°C/W
GND
2
SW
3 1
Z PACKAGE
3-LEAD TO-92 PLASTIC
BOTTOM VIEW
OUT
V
LT1109 • POI01
LT1109CZ-5
LT1109CZ-12
ORDER PART
NUMBER
ORDER PART
NUMBER
S8 PART
MARKING
ORDER PART
NUMBER
LT1109CS8
LT1109CS8-5
LT1109CS8-12
LT1109CN8
LT1109CN8-5
LT1109CN8-12
1109
10905
10912
Operating Temperature Range ..................... 0°C to 70°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................. 300°C
Switch Current........................................................ 1.2A
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
(Voltages Referred to GND Pin)
Supply Voltage (V
OUT
) .............................. –0.4V to 20V
SW Pin Voltage..........................................–0.4V to 50V
SHUTDOWN Pin Voltage......................................... 6.0V
Maximum Power Dissipation ............................. 300mW