LT1107 Linear Technology, LT1107 Datasheet - Page 5

• Manufacturer Part Number: LT1107
• Description: Micropower DC/DC Converter Adjustable and Fixed 5V/ 12V
• Manufacturer: Linear Technology

PI
I
lower current limit is desired, connect a resistor between
I
to approximately 400mA.
V
SW1 (Pin 3): Collector of Power Transistor. For step-up
mode connect to inductor/diode. For step-down mode
connect to V
SW2 (Pin 4): Emitter of Power Transistor. For step-up
mode connect to ground. For step-down mode connect to
inductor/diode. This pin must never be allowed to go more
than a Schottky diode drop below ground.
TYPICAL PERFOR
LIM
LIM
IN
100
5.3
5.2
5.1
5.0
4.9
4.8
4.7
90
80
70
60
50
40
30
U
(Pin 2): Input Supply Voltage.
(Pin 1): Connect this pin to V
and V
–55
Minimum/Maximum Frequency
vs ON Time, Step-Down Mode
LT1107-5
Output Voltage
4
–55 C
FU
–35
5
IN
–15
6
U
. A 220 resistor will limit the switch current
T
IN
A
C
7
TEMPERATURE (°C)
.
5
125 C
TI
ON TIME ( s)
8
25
O
9
45
U
10
0 C
S
65
11
T
85 105
W
12
A
70 C
1107 G16
A
13 14
1107 G11
IN
U
125
for normal use. Where
CE
C
12.20
12.15
12.10
12.05
12.00
11.95
11.90
11.85
11.80
HARA TERISTICS
100
90
80
70
60
50
40
30
–55
Minimum/Maximum Frequency
vs ON Time, Step-Up Mode
LT1107-12
Output Voltage
6
–55 C
–35
7
–15
T
C
8
A
T
= 25 C
A
9
TEMPERATURE (°C)
5
125 C
ON TIME ( s)
10
25
11
GND (Pin 5): Ground.
AO (Pin 6): Auxiliary Gain Block (GB) Output. Open collector,
can sink 300 A.
SET (Pin 7): GB Input. GB is an op amp with positive input
connected to SET pin and negative input connected to
1.25V reference.
FB/SENSE (Pin 8): On the LT1107 (adjustable), this pin
goes to the comparator input. On the LT1107-5 and
LT1107-12, this pin goes to the internal application resistor
that sets output voltage.
0 C
45
12
T
65
A
13
70 C
85 105
14
1107 G17
15 16
1107 G12
125
1.30
1.29
1.28
1.27
1.26
1.25
1.24
1.23
1.22
1.21
1.20
70
65
60
55
50
45
40
35
–55
–55
Duty Cycle
Step-Down Mode
LT1107
Feedback Voltage
–35
–35
–15
–15
TEMPERATURE (°C)
TEMPERATURE (°C)
5
5
25
25
45
45
65
65
LT1107
85 105
85 105
1107 G13
1107 G18
5
125
125