Datasheet

4
LT1109A
CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
W
IDAGRA
B
L
O
C
K
S
LT1109A (Adjustable)
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
12.3
12.2
12.1
12.0
11.9
11.8
11.7
25 75
1109A G09
–25 0
50 100 125
LT1109A-12
Output Voltage
LT1109A-5, LT1109A-12
–
+
V
IN
1.25V
REF
R2
250k
COMP
A1
R1*
SWSENSE
DRIVER
SHUTDOWN
–
+
V
IN
1.25V
REF
COMP
A1
SW
FB
DRIVER
*LT1109A-5: R1 = 83k
LT1109A-12: R1 = 29k
1109A BD
120kHz
OSC
120kHz
OSC
GND
PGND PGND
SHUTDOWN
Q1
Q1
GND
t
ON
(µs)
3.0
OSCILLATOR FREQUENCY (kHz)
160
150
140
130
120
110
100
90
80
7.0
1109A G10
4.0
5.0
6.0
8.0
3.5 4.5
5.5 6.5 7.5
0°C ≤ T
A
≤ 70°C
T
A
= 25°C
Minimum/Maximum
Oscillator Frequency vs t
ON