LT1111 LINER [Linear Technology], LT1111 Datasheet - Page 5

• Manufacturer Part Number: LT1111
• Description: Micropower DC/DC Converter Adjustable and Fixed 5V, 12V
• Manufacturer: LINER [Linear Technology]

TYPICAL PERFOR
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.
LIM
LIM
IN
340
320
280
400
380
360
300
260
240
220
200
U
(Pin 2): Input Supply Voltage.
(Pin 1): Connect this pin to V
and V
0
Quiescent Current
FU
3
IN
6
U
. A 220 resistor will limit the switch current
IN
100
INPUT VOLTAGE (V)
C
9
90
80
70
60
50
40
30
20
10
.
0
–50
TI
12 15 18 21 24 27 30
Set Pin Bias Current
O
–25
U
S
0
TEMPERATURE ( C)
W
LT1111 • TPC10
25
A
IN
50
U
for normal use. Where
CE
75
LT1111 • TPC13
C
100
500
450
400
350
300
250
200
150
100
HARA TERISTICS
–50
125
Quiescent Current
–25
C
0
TEMPERATURE ( C)
25
GND (Pin 5): Ground.
A0 (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 LT1111 (adjustable) this pin
goes to the comparator input. On the LT1111-5 and
LT1111-12, this pin goes to the internal application resistor
that sets output voltage.
50
75
LT1111 • TPC11
100
100
90
80
70
60
50
40
30
20
10
125
0
–50
Feedback Bias Current
–25
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
TEMPERATURE ( C)
10
Maximum Switch Current
vs R
25
STEP-DOWN
LIM
V
IN
50
= 12V
75
STEP-UP
2V V
R
LIM
LT1111 • TPC14
100
100
( )
IN
125
5V
LT1111
LT1111 • TPC12
5
1000