LT1111_15 Datasheet, PDF (5/16 Pages) Linear Technology – Micropower DC/DC Converter Adjustable and Fixed 5V, 12V

LT1111
TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current
400
380
360
340
320
300
280
260
240
220
200
0 3 6 9 12 15 18 21 24 27 30
INPUT VOLTAGE (V)
LT1111 • TPC10
Quiescent Current
500
450
400
350
300
250
200
150
100
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
LT1111 • TPC11
Maximum Switch Current
vs R_LIM
1.5
1.4
1.3
1.2
1.1
1.0
STEP-UP
0.9
2V ≤ V_IN ≤ 5V
0.8
0.7
0.6
STEP-DOWN
0.5
0.4
V_IN = 12V
0.3
0.2
0.1
10
100
R_LIM (Ω)
1000
LT1111 • TPC12
Set Pin Bias Current
100
90
80
70
60
50
40
30
20
10
0
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
LT1111 • TPC13
Feedback Bias Current
100
90
80
70
60
50
40
30
20
10
0
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
LT1111 • TPC14
PI FU CTI S
I_LIM (Pin 1): Connect this pin to V_IN for normal use. Where
lower current limit is desired, connect a resistor between
I_LIM and V_IN. A 220Ω resistor will limit the switch current
to approximately 400mA.
V_IN (Pin 2): Input Supply Voltage.
SW1 (Pin 3): Collector of Power Transistor. For step-up
mode connect to inductor/diode. For step-down mode
connect to V_IN.
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.
GND (Pin 5): Ground.
A0 (Pin 6): Auxiliary Gain Block (GB) Output. Open collector,
can sink 300µA.
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.
1111fd
5