Datasheet LT1308A, LT1308B (Analog Devices) - 4

LT1308A/LT1308B
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. Industrial Grade –40°C to 85°C. VIN = 1.2V, VSHDN = VIN, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
fOSC Switching Frequency l 500 600 750 kHz Maximum Duty Cycle l 82 90 % Switch Current Limit Duty Cycle = 30% (Note 4) 2 3 4.5 A Switch VCESAT ISW = 2A (25°C, – 40°C), VIN = 1.5V 290 350 mV ISW = 2A (85°C), VIN = 1.5V 330 400 mV Burst Mode Operation Switch Current Limit VIN = 2.5V, Circuit of Figure 1 400 mA (LT1308A) Shutdown Pin Current VSHDN = 1.1V l 2 5 μA VSHDN = 6V l 20 35 μA VSHDN = 0V 0.01 0.1 μA LBI Threshold Voltage 196 200 204 mV l 193 200 207 mV LBO Output Low ISINK = 50μA l 0.1 0.25 V LBO Leakage Current VLBI = 250mV, VLBO = 5V l 0.01 0.1 μA LBI Input Bias Current (Note 5) VLBI = 150mV 33 100 nA Low-Battery Detector Gain 3000 V/V Switch Leakage Current VSW = 5V l 0.01 10 μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
Switch current limit guaranteed by design and/or correlation to may cause permanent damage to the device. Exposure to any Absolute static tests. Duty cycle affects current limit due to ramp generator (see Maximum Rating condition for extended periods may affect device Block Diagram). reliability and lifetime.
Note 5:
Bias current fl ows out of LBI pin.
Note 2:
The LT1308ACS8, LT1308ACF, LT1308BCS8 and LT1308BCF are
Note 6:
Connect the four GND pins (Pins 4–7) together at the device. designed, characterized and expected to meet the industrial temperature Similarly, connect the three SW pins (Pins 8–10) together and the two V limits, but are not tested at –40°C and 85°C. I grade devices are IN pins (Pins 11, 12) together at the device. guaranteed over the –40°C to 85°C operating temperature range.
Note 3:
Bias current fl ows into FB pin.
TYPICAL PERFORMANCE CHARACTERISTICS LT1308B LT1308A LT1308A 3.3V Output Effi ciency 3.3V Output Effi ciency 5V Output Effi ciency
95 95 95 VIN = 4.2V 90 V 90 90 V IN = 2.5V IN = 1.8V V V IN = 2.5V IN = 3.6V 85 85 VIN = 1.8V 85 80 80 80 75 VIN = 1.2V 75 V 75 VIN = 1.5V IN = 1.2V VIN = 2.5V 70 70 70 EFFICIENCY (%) 65 EFFICIENCY (%) 65 EFFICIENCY (%) 65 60 60 60 55 55 55 50 50 50 1 10 100 1000 1 10 100 1000 1 10 100 1000 LOAD CURRENT (mA) LOAD CURRENT (mA) LOAD CURRENT (mA) 1308A/B G01 1308A/B G02 1308A/B G03 1308abfb 4