Datasheet LTC3878 (Analog Devices) - 3

LTC3878 e

lecTrical characTerisTics
The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 15V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
tOFF(MIN) Minimum Off-Time ION = 30µA 220 300 ns VSENSE(MAX) Valley Current Sense Threshold VRNG = 1V, VFB = 0.76V l 108 133 165 mV VPGND – VSW VRNG = 0V, VFB = 0.76V l 74 93 119 mV Peak Current = Valley + Ripple VRNG = INTVCC, VFB = 0.76V l 152 186 224 mV VSENSE(MIN) Minimum Current Sense Threshold VRNG = 1V, VFB = 0.84V –67 mV VPGND – VSW VRNG = 0V, VFB = 0.84V –47 mV Forced Continuous Operation VRNG = INTVCC, VFB = 0.84V –93 mV VRUN/SS RUN/SS Pin On Threshold VRUN/SS Rising 1.4 1.5 1.6 V Soft-Start Charging Current VRUN/SS = 0V –1.2 µA INTVCC(UVLO) INTVCC Undervoltage Lockout Falling l 3.3 3.9 V INTVCC(UVLOR) INTVCC Undervoltage Lockout Release Rising l 3.6 4 V TG Driver Pull-Up On-Resistance TG High 2.5 Ω TG Driver Pull-Down On-Resistance TG Low 1.2 Ω BG Driver Pull-Up On-Resistance BG High 2.5 Ω BG Driver Pull-Down On-Resistance BG Low 0.7 Ω TG Rise Time CLOAD = 3300pF (Note 5) 20 ns TG Fall Time CLOAD = 3300pF (Note 5) 20 ns BG Rise Time CLOAD = 3300pF (Note 5) 20 ns BG Fall Time CLOAD = 3300pF (Note 5) 20 ns TG/BG t1D Top Gate Off to Bottom Gate On Delay CLOAD = 3300pf Each Driver (Note 5) 15 ns Synchronous Switch-On Delay Time TG/BG t2D Bottom Gate Off to Top Gate On Delay CLOAD = 3300pf Each Driver (Note 5) 15 ns Synchronous Switch-On Delay Time
Internal VCC Regulator
Internal VCC Voltage 6V < VIN < 38V 5.15 5.3 5.45 V Internal VCC Load Regulation ICC = 0mA to 20mA –0.1 ±2 %
PGOOD Output
PGOOD Upper Threshold VFB Rising 5.5 7.5 9.5 % PGOOD Lower Threshold VFB Falling –5.5 –7.5 –9.5 % PGOOD Hysteresis VFB Returning 2 3.5 % PGOOD Low Voltage IPGOOD = 5mA 0.15 0.4 V PGOOD Turn-On Delay 12 µs
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
The LTC3878E is guaranteed to meet specifications from may cause permanent damage to the device. Exposure to any Absolute 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature Maximum Rating condition for extended periods may affect device range are assured by design, characterization and correlation with reliability and lifetime. statistical process controls. The LTC3878I is guaranteed to meet
Note 2:
TJ is calculated from the ambient temperature TA and power specifications over the full –40°C to 85°C operating temperature range. dissipation PD as follows:
Note 5:
Rise and fall time are measured using 10% and 90% levels. Delay TJ = TA + (PD • 110°C/W) times are measured using 50% levels.
Note 3:
The LTC3878 is tested in a feedback loop that adjusts VFB to achieve a specified error amplifier output voltage (ITH). 3878fa Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration order information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts