Datasheet LT3508 (Analog Devices) - 3

LT3508
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 12V unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage, VIN1 l 3.4 3.7 V Minimum Operating Voltage, VIN2 VIN1 = 12V l 2.5 3.0 V VIN1 Quiescent Current Not Switching 4.3 5.2 mA VIN2 Quiescent Current Not Switching 320 500 μA Shutdown Current (VIN1 + VIN2) VSHDN = 0.3V 0.1 2 μA FB Voltage 0.790 0.800 0.814 V l 0.784 0.816 V FB Pin Bias Current (Note 3) VFB = 0.800V, VC = 0.5V l 50 300 nA FB Voltage Line Regulation 5V < VIN < 40V 0.01 %/V Error Amp Transconductance 300 μS Error Amp Voltage Gain 600 V/V VC to Switch Current Gain 2.5 A/V Switching Frequency RT = 33.2k l 0.92 1 1.06 MHz Switching Phase RT = 33.2k 150 180 210 Deg Maximum Duty Cycle (Note 4) RT = 33.2k l 84 90 % RT = 7.50k 80 % RT = 169k 98 % Foldback Frequency RT = 33.2k, VFB = 0V 120 kHz Switch Current Limit (Note 5) Duty Cycle = 15% l 2.0 2.6 3.2 A Switch VCESAT ISW = 1.5A 300 mV Switch Leakage Current 0.01 1 μA Minimum Boost Voltage 1.7 2.5 V Boost Pin Current ISW = 1.5A, VBOOST = 17V 35 50 mA TRACK/SS Pin Current VTRACK/SS = 0V 0.8 1.2 2.2 μA PG Threshold Offset VFB Rising 56 75 110 mV PG Voltage Output Low VFB = 0.6V, IPG = 250μA 0.13 0.4 V PG Pin Leakage VPG = 2V 0.01 1 μA SHDN Threshold Voltage 2.53 2.63 2.73 V SHDN Input Current (Note 6) VSHDN = 60mV Above Threshold Voltage 6 8 10 μA SHDN Threshold Current Hysteresis 5.5 7.5 9.5 μA SYNC Threshold Voltage 1 1.25 1.5 V SYNC Input Frequency 0.25 2.5 MHz
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 3:
Current fl ows out of pin. may cause permanent damage to the device. Exposure to any Absolute
Note 4:
VBOOST =12V. Circuitry increases the maximum duty cycle of the Maximum Rating condition for extended periods may affect device LT3508 when VBOOST > VIN + 2.5V. See Minimum Operating Voltage in the reliability and lifetime. Applications Information section for details.
Note 2:
The LT3508E is guaranteed to meet performance specifi cations
Note 5:
Current limit is guaranteed by design and/or correlation to static from 0°C to 125°C junction temperature. Specifi cations over the –40°C test. Slope compensation reduces current limit at higher duty cycles. to 125°C operating junction temperature range are assured by design,
Note 6:
Current fl ows into pin. characterization and correlation with statistical process controls. The
Note 7:
This IC includes overtemperature protection that is intended LT3508I is guaranteed over the full –40°C to 125°C operating junction to protect the device during momentary overload conditions. Junction temperature range. The LT3508H is guaranteed over the full –40°C to temperature will exceed the maximum operating junction temperature 150°C operating junction temperature range. High junction temperatures range when overtemperature protection is active. Continuous operation degrade operating lifetimes. Operating lifetime is derated at junction above the specifi ed maximum operating junction temperature may impair temperatures greater than 125°C. device reliability. 3508fd 3 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION 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