Datasheet LT3745 (Analog Devices) - 3

LT3745
e lecTrical characTerisTics The
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denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, VCC = 3.3V, VEN/UVLO = 1.5V, VFB = 1.5V, VISP = VISN = 0V, RT = 105k, RISET = 60.4k, CCAP = 0.47µF to VIN, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply
VIN VIN Operating Voltage l 6 55 V IVIN VIN Supply Current VEN/UVLO = 0V 0.2 2 µA No Switching 0.4 0.55 mA VCC VCC Operating Voltage l 3 5.5 V IVCC VCC Supply Current (Note 4) VEN/UVLO = 0V 0.1 1 µA LED Channel Off, 30MHz Data Off 3.1 3.6 mA LED Channel On, 30MHz Data Off 7 mA LED Channel On, 30MHz Data On 16 mA
Undervoltage Lockout (UVLO)
VCC UVLO Threshold VCC Rising 2.82 2.89 2.96 V VCC Falling 2.61 2.68 2.75 V EN/UVLO Shutdown Threshold IVCC <20µA 0.35 V UVLO Threshold VEN/UVLO Rising 1.28 1.31 1.34 V VEN/UVLO Falling 1.19 1.22 1.25 V IEN/UVLO EN/UVLO Bias Current VEN/UVLO = VCC = 3.3V 0.1 1 µA (VIN – VCAP) UVLO Threshold (VIN – VCAP) Rising 4.6 4.9 5.2 V (VIN – VCAP) Falling 4.2 4.5 4.8 V
Soft-Start (SS)
ISS Soft-Start Charge Current VSS = 1V –16 –12 –8 µA Soft-Start Discharge Current VSS = VCC, VEN/UVLO = 1V 330 µA VSS(TH) Soft-Start Reset Threshold 0.35 V
Oscillator
VRT RT Pin Voltage 1.186 1.205 1.224 V IRT RT Pin Current Limit VRT = 0V –80 µA fOSC Oscillator Frequency RT = 280k 188 200 212 kHz RT = 105k 475 500 525 kHz RT = 46.4k 965 1015 1065 kHz fSYNC Sync Frequency Range (Note 5) RT = 348k 200 1000 kHz SYNC LOGIC VCC = 3V to 5.5V High Level Voltage 2.4 VCC V Low Level Voltage 0 0.6 V
Error Amplifiers and Loop Dynamics
VFB FB Regulation Voltage VISN = 5V l 1.186 1.210 1.234 V IFB FB Input Bias Current VISN = 5V, VFB Regulated –120 nA LED Regulation Voltage VISN = 5V, VFB = 1V 0.63 0.715 0.8 V TOFF(MIN) Minimum GATE Off-Time VISP = VISN = 5V, VFB = 1V 120 ns TON(MIN) Minimum GATE On-Time (VISP – VISN) = 60mV, VISN = 5V, VFB = 1V 200 ns
Current Sense Amplifier
ISP/ISN Pin Common Mode VISP = VISN l 0 36 V VIN to ISN Dropout Voltage (VIN – VISN) VISP = VISN, VFB = 1V l 1.7 2.1 V Current Limit Sense Threshold (VISP – VISN) VFB = 1V 34 46.5 59 mV IISP ISP Input Bias Current –24 µA IISN ISN Input Bias Current –48 µA 3745f 3 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Timing Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Package Description Typical Application Related Parts