LT1107 WUTYPICAL PERFOR A CE CHCARA TERISTICSMinimum/Maximum FrequencyMinimum/Maximum FrequencyDuty Cyclevs ON Time, Step-Down Modevs ON Time, Step-Up ModeStep-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 LT1107-5LT1107-12LT1107Output VoltageOutput VoltageFeedback 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 UUOUPIFU CTISILIM (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