Datasheet LT3755, LT3755-1, LT3755-2 (Analog Devices) - 4

LT3755/LT3755-1/LT3755-2
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 24V, SHDN/UVLO = 24V, CTRL = 2V, PWM = 5V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
LED Current Sense Amplifier gm V(ISP – ISN) = 100mV 120 µS VC Output Impedance 1V < VC < 2V 15000 kΩ VC Standby Input Bias Current PWM = 0V –20 20 nA FB Regulation Voltage (VFB) 1.232 1.250 1.265 V ISP = ISN l 1.220 1.250 1.270 V J-Grade l 1.215 1.250 1.275 V FB Amplifier gm FB = VFB, ISP = ISN 480 µS FB Pin Input Bias Current Current Out of Pin 40 100 nA FB Open LED Threshold OPENLED Falling (LT3755 and LT3755-2) VFB – VFB – VFB – V 65mV 50mV 40mV FB Overvoltage Threshold PWMOUT Falling VFB + VFB + VFB + V 50mV 60mV 75mV VC Current Mode Gain – (∆VVC/∆VSENSE) 4 V/V
Oscillator
Switching Frequency RT = 100k l 90 100 125 kHz RT = 10k 925 1000 1050 kHz Minimum Off-Time 170 ns
Linear Regulator
INTVCC Regulation Voltage 7 7.15 7.3 V Dropout (VIN – INTVCC) IINTVCC = –10mA, VIN = 7V 350 mV INTVCC Undervoltage Lockout 3.9 4.1 4.3 V INTVCC Current Limit 29 34 40 mA INTVCC Current in Shutdown SHDN/UVLO = 0V, INTVCC = 7V 8 12 µA
Logic Inputs/Outputs
PWM Input High Voltage l 1.5 V PWM Input Low Voltage l 0.4 V PWM Pin Resistance to GND 45 60 kΩ PWMOUT Output Low (VOL) 0 50 mV PWMOUT Output High (VOH) INTVCC – V 0.05 SHDN/UVLO Threshold Voltage Falling E-, I-Grades l 1.185 1.220 1.245 V H-Grade l 1.175 1.245 V J-Grade l 1.159 1.260 V SHDN/UVLO Rising Hysteresis 20 mV SHDN/UVLO Input Low Voltage IVIN Drops Below 1µA 0.4 V SHDN/UVLO Pin Bias Current Low SHDN/UVLO = 1.15V 1.7 2.05 2.5 µA SHDN/UVLO Pin Bias Current High SHDN/UVLO = 1.30V 10 100 nA OPENLED Output Low (VOL) IOPENLED = 0.5mA (LT3755 and LT3755-2) 200 mV SYNC Pin Resistance to GND LT3755-1 Only 30 kΩ SYNC Input High LT3755-1 Only 1.5 V SYNC Input Low LT3755-1 Only 0.4 V Rev. E 4 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts