Datasheet LTC3785-1 (Analog Devices) - 3

LTC3785-1
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = ISVOUT = VDRV = VBST1 = VBST2 = 3.6V, RT = 49.9k, RILSET = 59k. PARAMETER CONDITIONS MIN TYP MAX UNITS VCC Regulator
VCC Maximum Regulating Voltage VIN = 5V, IVCC = –20mA l 4.15 4.35 4.55 V VCC Regulation Voltage VIN = 3.6V, IVCC = –20mA l 3.3 3.5 3.6 V VCC Regulator Sink Current ISVOUT = VCC = 5V 800 μA
Run/Soft-Start
RUN/SS Threshold When IC is Enabled l 0.35 0.7 1.1 V When EA is at Maximum Boost Duty Cycle 1.9 V RUN/SS Input Current RUN/SS = 0V –1 μA RUN/SS Discharge Current During Current Limit 20 30 μA
Current Limit
Current Limit Sense Threshold ISVIN to ISSW1, RILSET = 121k l 20 60 100 mV ISVIN to ISSW1, RILSET = 59k l 55 105 155 mV Reverse Current Limit Sense Threshold ISSW2 to ISVOUT, CCM > 2V l –50 –110 –170 mV ISSW2 to ISVOUT, CCM < 0.4V l –15 –35 mV Input Current ISVIN 80 150 μA ISVOUT 10 20 μA ISSW1, ISSW2 0.1 5 μA CCM Input Threshold (High) l 2.2 V CCM Input Threshold (Low) l 0.4 V CCM Input Current CMM = 3.6V 0.01 1 μA
Burst Mode Operation
Mode Threshold l 0.8 1.5 2.2 V Mode Input Current 0.01 1 μA tON Time 1.4 μs
Oscillator
Frequency Accuracy l 370 509 650 kHz
Switching Characteristics
Maximum Duty Cycle Boost (% Switch BG2 On) l 80 90 % Buck (% Switch TG1 On) 99 % TG1, TG2 Driver Impedance 2 Ω BG1, BG2 Driver Impedance 2 Ω TG1, TG2 Rise Time CLOAD = 3300pF (Note 3) 20 ns BG1, BG2 Rise Time CLOAD = 3300pF (Note 3) 20 ns TG1, TG2 Fall Time CLOAD = 3300pF (Note 3) 20 ns BG1, BG2 Fall Time CLOAD = 3300pF (Note 3) 20 ns Buck Driver Nonoverlap Time TG1 to BG1 100 ns Boost Driver Nonoverlap Time TG2 to BG2 100 ns
Power Good
Undervoltage Threshold VSENSE Falling, % Below FB Regulation Voltage –5 –7.5 –10.5 % Undervoltage Hysteresis 1.5 % Overvoltage Threshold VSENSE Rising % Above FB Regulation Voltage, 5 7.5 10.5 % MODE = 0V Overvoltage Hysteresis –2 % 37851fa 3