LTC3808 ELECTRICAL CHARACTERISTICS The ● indicates specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 ° C. VIN = 4.2V unless otherwise noted.PARAMETERCONDITIONSMINTYPMAXUNITS Overvoltage Protect Hysteresis 20 mV Auxiliary Feedback Threshold 0.325 0.4 0.475 V Top Gate (TG) Drive Rise Time CL = 3000pF 40 ns Top Gate (TG) Drive Fall Time CL = 3000pF 40 ns Bottom Gate (BG) Drive Rise Time CL = 3000pF 50 ns Bottom Gate (BG) Drive Fall Time CL = 3000pF 40 ns Maximum Current Sense Voltage (∆VSENSE(MAX)) IPRG = Floating (Note 6) ● 110 125 140 mV (SENSE+ – SW) IPRG = 0V (Note 6) ● 70 85 100 mV IPRG = VIN (Note 6) ● 185 204 223 mV Soft-Start Time (Internal) Time for VFB to Ramp from 0.05V to 0.55V 0.5 0.74 0.9 ms Oscillator and Phase-Locked Loop Oscillator Frequency Unsynchronized (SYNC/MODE Not Clocked) PLLLPF = Floating 480 550 600 kHz PLLLPF = 0V 260 300 340 kHz PLLLPF = VIN 650 750 825 kHz Phase-Locked Loop Lock Range SYNC/MODE Clocked Minimum Synchronizable Frequency 200 250 kHz Maximum Synchronizible Frequency 750 1000 kHz Phase Detector Output Current Sinking fOSC > fSYNC/MODE –3 µA Sourcing fOSC < fSYNC/MODE 3 µA Spread Spectrum Frequency Range Minimum Switching Frequency 460 kHz Maximum Switching Frequency 635 kHz SYNC/MODE Pull-Down Current SYNC/MODE = 2.2V 2.6 µA PGOOD Output PGOOD Voltage Low IPGOOD Sinking 1mA 50 mV PGOOD Trip Level VFB with Respect to Set Output Voltage VFB < 0.6V, Ramping Positive –13 –10.0 –7 % VFB < 0.6V, Ramping Negative –16 –13.3 –10 % VFB > 0.6V, Ramping Negative 7 10.0 13 % VFB > 0.6V, Ramping Positive 10 13.3 16 % Note 1: Absolute Maximum Ratings are those values beyond which the life Note 4: Dynamic supply current is higher due to gate charge being of a device may be impaired. delivered at the switching frequency. Note 2: The LTC3808E is guaranteed to meet specified performance from Note 5: The LTC3808 is tested in a feedback loop that servos ITH to a 0°C to 70°C. Specifications over the –40°C to 85°C operating range are specified voltage and measures the resultant VFB voltage. assured by design characterization, and correlation with statistical process Note 6: Peak current sense voltage is reduced dependent on duty cycle to controls. a percentage of value as shown in Figure 1. Note 3: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • θJA °C/W) 3808f 3
