Datasheet LT1107 (Analog Devices) - 5

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