LT1107_15 Datasheet, PDF (5/16 Pages) Linear Technology – Micropower DC/DC Converter Adjustable and Fixed 5V, 12V

TYPICAL PERFOR A CE CHARACTERISTICS
LT1107
Minimum/Maximum Frequency
vs ON Time, Step-Down Mode
100
90
80
0°C ≤ T_A ≤ 70°C
70
60
50
–55°C ≤ T_A ≤ 125°C
40
30
4 5 6 7 8 9 10 11 12 13 14
ON TIME (µs)
1107 G11
LT1107-5
Output Voltage
5.3
5.2
5.1
5.0
4.9
4.8
4.7
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1107 G16
Minimum/Maximum Frequency
vs ON Time, Step-Up Mode
100
90
0°C ≤ T_A ≤ 70°C
80
70
60
50
T_A = 25°C
40 ^{–55°C ≤ TA ≤ 125°C}
30
6 7 8 9 10 11 12 13 14 15 16
ON TIME (µs)
1107 G12
LT1107-12
Output Voltage
12.20
12.15
12.10
12.05
12.00
11.95
11.90
11.85
11.80
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1107 G17
Duty Cycle
Step-Down Mode
70
65
60
55
50
45
40
35
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
LT1107
Feedback Voltage
1107 G13
1.30
1.29
1.28
1.27
1.26
1.25
1.24
1.23
1.22
1.21
1.20
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1107 G18
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.
AO (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 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.
1107fa
5