LT3957A ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temp-erature range, otherwise specifications are at TA ≈ TJ = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted.PARAMETERCONDITIONSMINTYPMAXUNITS INTVCC Current Limit VIN = 40V 32 40 55 mA VIN = 15V 95 mA INTVCC Load Regulation (ΔVINTVCC / VINTVCC) 0 < IINTVCC < 20mA, VIN = 8V –1 –0.5 % INTVCC Line Regulation (ΔVINTVCC / [ΔVIN • VINTVCC]) 6V < VIN < 40V 0.02 0.05 %/V Dropout Voltage (VIN – VINTVCC) VIN = 5V, IINTVCC = 20mA, VC = 0V 450 mV INTVCC Current in Shutdown EN/UVLO = 0V, INTVCC = 6V 17 μA INTVCC Voltage to Bypass Internal LDO 5.5 V Logic Inputs EN/UVLO Threshold Voltage Falling VIN = INTVCC = 6V l 1.17 1.22 1.27 V EN/UVLO Voltage Hysteresis 20 mV EN/UVLO Input Low Voltage IVIN Drops Below 1μA 0.4 V EN/UVLO Pin Bias Current Low EN/UVLO = 1.15V 1.7 2 2.5 μA EN/UVLO Pin Bias Current High EN/UVLO = 1.33V 20 100 nA Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 3: The LT3957A is tested in a feedback loop which servos VFBX to the may cause permanent damage to the device. Exposure to any Absolute reference voltages (1.6V and –0.8V) with the VC pin forced to 1.3V. Maximum Rating condition for extended periods may affect device Note 4: FBX overvoltage lockout is measured at VFBX(OVERVOLTAGE) relative reliability and lifetime. to regulated VFBX(REG). Note 2: The LT3957AE is guaranteed to meet performance specifications Note 5: For 3V ≤ VIN < 6V, the EN/UVLO pin must not exceed VIN. from the 0°C to 125°C operating junction temperature. Specifications over Note 6: EN/UVLO = 1.33V when VIN = 3V. the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3957AI is guaranteed over the full –40°C to 125°C operating junction temperature range. TYPICAL PERFORMANCE CHARACTERISTICS TA ≈ TJ = 25°C, unless otherwise noted.Positive Feedback VoltageNegative Feedback VoltageQuiescent Currentvs Temperature, VINvs Temperature, VINvs Temperature, VIN 1605 –788 1.8 –790 VIN = INTVCC = 3V VIN = 40V SHDN/UVLO = 1.33V 1600 VIN = 24V –792 1.7 VIN = 40V –794 V V IN = 8V IN = 24V V 1590 IN = 8V –796 1.6 –798 V V 1585 IN = INTVCC = 3V, VIN = 40V IN = INTVCC = 3V SHDN –800 /UVLO = 1.33V VIN = 24V QUIESCENT CURRENT (mA) 1.5 –802 REGULATED FEEDBACK VOLTAGE (mV) REGULATED FEEDBACK VOLTAGE (mV) 1580 –804 1.4 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3957A G01 3957A G02 3957A G03 3957afa 4