Datasheet LT3478, LT3478-1 (Analog Devices) - 3

LT3478/LT3478-1
The ELECTRICAL CHARACTERISTICS
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denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. SW = open, VIN = VS = L = VOUT =
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S
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H
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D
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N = 2.7V, LED = open, SS = open, PWM = CTRL1, CTRL2 = 1.25V, VREF = open, VC = open, RT = 31.6k. PARAMETER CONDITIONS MIN TYP MAX UNITS
Frequency: fOSC 2.25MHz RT = 9.09k 2 2.25 2.6 MHz Line Regulation fOSC RT = 31.6k, 2.7V < VIN < 36V 0.05 0.2 %/V Nominal RT Pin Voltage 0.64 V Maximum Duty Cycle RT = 31.6k ● 80 88 % RT = 200k 97 % RT = 9.09k 73 % LED Current to VC Current Gain (Note 6) 770 µA/A LED Current to VC Voltage Gain (Note 6) 400 V/A VC to Switch Current Gain 13 A/V VC Source Current (Out of Pin) CTRL1 = 0.4V, VC = 1V 40 µA VC Sink Current CTRL1 = 0V, VC = 1V 40 µA VC Switching Threshold 0.65 V VC High Level (VOH) CTRL1 = 0.4V 1.5 V VC Low Level (VOL) CTRL1 = 0V 0.2 V Inductor Current Limit 2.7V < VS < 36V ● 4.5 6 6.8 A Switch Current Limit ● 4.5 6.3 7.5 A Switch VCE SAT ISW = 4.5A 270 mV Switch Leakage Current SW = 42V, VC = 0V 1 µA VOUT Overvoltage Protection (OVP) OVPSET = 1V 41 V (Rising) OVPSET = 0.3V 12.3 V Full Scale LED Current (LT3478-1) CTRL1 = VREF, Current Out of LED Pin 1010 1050 1090 mA 700mA LED Current (LT3478-1) CTRL1 = 700mV, Current Out of LED Pin ● 655 700 730 mA 350mA LED Current (LT3478-1) CTRL1 = 350mV, Current Out of LED Pin 325 350 375 mA 100mA LED Current (LT3478-1) CTRL1 = 100mV, Current Out of LED Pin 70 100 130 mA Full Scale LED Current VSENSE (LT3478) CTRL1 = VREF, VSENSE = VVOUT – VLED 101 105 109 mV CTRL1 = 700mV, VSENSE (LT3478) CTRL1 = 700mV, VSENSE = VVOUT – VLED ● 67 70.5 74 mV CTRL1 = 350mV, VSENSE (LT3478) CTRL1 = 350mV, VSENSE = VVOUT – VLED 33 35.5 38 mV CTRL1 = 100mV, VSENSE (LT3478) CTRL1 = 100mV, VSENSE = VVOUT – VLED 7 10 13 mV CTRL1, 2 Input Currents CTRL1 = 100mV, CTRL2 = 1.25V or 40 nA CTRL2 = 100mV, CTRL1 = 1.25V (Current Out of Pin) OVPSET Input Current OVPSET = 1V, VOUT = 41V (Current Out of Pin) 200 nA PWM Switching Threshold 0.8 1 1.2 V VC Pin Current in PWM Mode VC = 1V, PWM = 0 1 50 nA OUT Pin Current in PWM Mode PWM = 0 1 100 nA SS Low Level (VOL) I(SS) = 20µA 0.15 V SS Reset Threshold VC = 0V 0.25 V SS High Level (VOH) VC = 0V 1.5 V Soft-Start (SS) Pin Charge Current SS = 1V, Current Out of Pin, VC = 0V 12 µA Soft-Start (SS) Pin Discharge Current SS = 0.5V, VC = 0V 350 µA 34781f 3