Datasheet LT8645S, LT8646S (Analog Devices) - 4

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ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN TYP MAX UNITS
LT8646S VC Pin to Switch Current Gain 8 A/V LT8646S VC Clamp Voltage 2.6 V BIAS Pin Current Consumption VBIAS = 3.3V, fSW = 2MHz 22 mA Minimum On-Time ILOAD = 2A, SYNC = 0V l 40 65 ns ILOAD = 2A, SYNC = 2V l 35 60 ns Minimum Off-Time 80 110 ns Oscillator Frequency RT = 221k l 180 210 240 kHz RT = 60.4k l 665 700 735 kHz RT = 18.2k l 1.8 1.95 2.1 MHz Top Power NMOS On-Resistance ISW = 1A 36 mΩ Top Power NMOS Current Limit l 10.5 14 17.5 A Bottom Power NMOS On-Resistance VINTVCC = 3.4V, ISW = 1A 25 mΩ Bottom Power NMOS Current Limit VINTVCC = 3.4V 8.5 11 13.5 A SW Leakage Current VIN = 42V, VSW = 0V, 42V –1.5 1.5 µA EN/UV Pin Threshold EN/UV Rising l 0.95 1.01 1.07 V EN/UV Pin Hysteresis 45 mV EN/UV Pin Current VEN/UV = 2V –20 20 nA PG Upper Threshold Offset from VFB VFB Falling l 5 7.5 10 % PG Lower Threshold Offset from VFB VFB Rising l –10.5 –8 –5.5 % PG Hysteresis 0.4 % PG Leakage VPG = 3.3V –40 40 nA PG Pull-Down Resistance VPG = 0.1V l 750 2000 Ω SYNC/MODE Threshold SYNC/MODE DC and Clock Low Level Voltage l 0.7 0.9 V SYNC/MODE Clock High Level Voltage l 1.2 1.4 V SYNC/MODE DC High Level Voltage l 2.2 2.55 2.9 V Spread Spectrum Modulation RT = 60.4k, VSYNC = 3.3V 24 % Frequency Range Spread Spectrum Modulation Frequency VSYNC = 3.3V 2.5 kHz TR/SS Source Current l 1.2 1.9 2.6 µA TR/SS Pull-Down Resistance Fault Condition, TR/SS = 0.1V 220 Ω
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 3:
θ values determined per JEDEC 51-7, 51-12. See Applications may cause permanent damage to the device. Exposure to any Absolute Information Section for information on improving the thermal resistance Maximum Rating condition for extended periods may affect device and for actual temperature measurements of a demo board in typical reliability and lifetime. operating conditions.
Note 2:
The LT8645SE/LT8646SE is guaranteed to meet performance
Note 4:
This IC includes overtemperature protection that is intended to specifications from 0°C to 125°C junction temperature. Specifications over protect the device during overload conditions. Junction temperature will the –40°C to 125°C operating junction temperature range are assured by exceed 150°C when overtemperature protection is active. Continuous design, characterization, and correlation with statistical process controls. operation above the specified maximum operating junction temperature The LT8645SI/LT8646SI is guaranteed over the full –40°C to 125°C will reduce lifetime. operating junction temperature range. The junction temperature (TJ, in °C) is calculated from the ambient temperature (TA in °C) and power dissipation (PD, in Watts) according to the formula: TJ = TA + (PD • θJA) where θJA (in °C/W) is the package thermal impedance. Rev. B 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 Package Description Revision History Typical Applications Related Parts