Datasheet LT3746 (Analog Devices) - 3

LT3746
elecTrical characTerisTics The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 24V, 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 3.3 4.0 mA LED Channel On, 30MHz Data Off 10 mA LED Channel On, 30MHz Data On 19 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 0.1 1 µA (VIN – VCAP) UVLO Threshold (VIN – VCAP) Rising 4.6 4.9 5.2 V (VIN – VCAP) Falling 4.1 4.4 4.7 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, VIN = 12V 185 205 225 kHz RT = 105k, VIN = 12V 470 510 550 kHz RT = 46.4k, VIN = 12V 950 1050 1150 kHz fSYNC Sync Frequency Range (Note 5) RT = 348k, VIN = 12V 200 1000 kHz SYNC LOGIC VIN = 12V, 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 VISP = VISN = 5V l 1.186 1.210 1.234 V IFB FB Input Bias Current VISP = VISN = 5V, VFB Regulated –120 nA LED Regulation Voltage VISP = VISN = 5V, VFB = 1V 0.44 0.54 0.64 V TOFF(MIN) Minimum GATE Off Time VIN = 12V, VISP = VISN = 5V, VFB = 1V 120 ns TON(MIN) Minimum GATE On Time VIN = 12V, (VISP – VISN) = 60mV, VISN = 5V, 200 ns VFB = 1V
Current Sense Amplifier
ISP/ISN Pin Common Mode VISP = VISN l 0 13 V VIN to ISN Dropout Voltage (VIN – VISN) VIN = 12V, VISP = VISN, VFB = 1V l 1.7 2 V Current Limit Sense Threshold (VISP – VISN) VFB = 1V 34 46.5 59 mV IISP ISP Input Bias Current –23 µA IISN ISN Input Bias Current –48 µA 3746fa For more information www.linear.com/3746 3 Document Outline Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Pin Functions Block Diagram Applications Information Typical Application Related Parts