Datasheet LTC1778, LTC1778-1 (Analog Devices) - 3

LTC1778/LTC1778-1
ELECTRICAL CHARACTERISTICS The
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25
°
C. VIN = 15V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
tOFF(MIN) Minimum Off-Time ION = 30µA 250 400 ns VSENSE(MAX) Maximum Current Sense Threshold VRNG = 1V, VFB = 0.76V ● 113 133 153 mV VPGND – VSW VRNG = 0V, VFB = 0.76V ● 79 93 107 mV VRNG = INTVCC, VFB = 0.76V ● 158 186 214 mV VSENSE(MIN) Minimum Current Sense Threshold VRNG = 1V, VFB = 0.84V – 67 mV VPGND – VSW VRNG = 0V, VFB = 0.84V – 47 mV VRNG = INTVCC, VFB = 0.84V – 93 mV ∆VFB(OV) Output Overvoltage Fault Threshold 5.5 7.5 9.5 % VFB(UV) Output Undervoltage Fault Threshold 520 600 680 mV VRUN/SS(ON) RUN Pin Start Threshold ● 0.8 1.5 2 V VRUN/SS(LE) RUN Pin Latchoff Enable Threshold RUN/SS Pin Rising 4 4.5 V VRUN/SS(LT) RUN Pin Latchoff Threshold RUN/SS Pin Falling 3.5 4.2 V IRUN/SS(C) Soft-Start Charge Current VRUN/SS = 0V – 0.5 – 1.2 –3 µA IRUN/SS(D) Soft-Start Discharge Current VRUN/SS = 4.5V, VFB = 0V 0.8 1.8 3 µA VIN(UVLO) Undervoltage Lockout VIN Falling ● 3.4 3.9 V VIN(UVLOR) Undervoltage Lockout Release VIN Rising ● 3.5 4 V TG RUP TG Driver Pull-Up On Resistance TG High 2 3 Ω TG RDOWN TG Driver Pull-Down On Resistance TG Low 2 3 Ω BG RUP BG Driver Pull-Up On Resistance BG High 3 4 Ω BG RDOWN BG Driver Pull-Down On Resistance BG Low 1 2 Ω TG tr TG Rise Time CLOAD = 3300pF 20 ns TG tf TG Fall Time CLOAD = 3300pF 20 ns BG tr BG Rise Time CLOAD = 3300pF 20 ns BG tf BG Fall Time CLOAD = 3300pF 20 ns
Internal VCC Regulator
VINTVCC Internal VCC Voltage 6V < VIN < 30V, VEXTVCC = 4V ● 4.7 5 5.3 V ∆VLDO(LOADREG) Internal VCC Load Regulation ICC = 0mA to 20mA, VEXTVCC = 4V – 0.1 ±2 % VEXTVCC EXTVCC Switchover Voltage ICC = 20mA, VEXTVCC Rising ● 4.5 4.7 V ∆VEXTVCC EXTVCC Switch Drop Voltage ICC = 20mA, VEXTVCC = 5V 150 300 mV ∆VEXTVCC(HYS) EXTVCC Switchover Hysteresis 200 mV
PGOOD Output (LTC1778 Only)
∆VFBH PGOOD Upper Threshold VFB Rising 5.5 7.5 9.5 % ∆VFBL PGOOD Lower Threshold VFB Falling – 5.5 – 7.5 – 9.5 % ∆VFB(HYS) PGOOD Hysteresis VFB Returning 1 2 % VPGL PGOOD Low Voltage IPGOOD = 5mA 0.15 0.4 V
Note 1:
Absolute Maximum Ratings are those values beyond which the life of
Note 4:
The LTC1778E is guaranteed to meet performance specifications from a device may be impaired. 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature
Note 2:
T range are assured by design, characterization and correlation with statistical J is calculated from the ambient temperature TA and power dissipation P process controls. The LTC1778I is guaranteed over the full – 40°C to 125°C D as follows: LTC1778E: T operating temperature range. J = TA + (PD • 130°C/W)
Note 3:
The LTC1778 is tested in a feedback loop that adjusts VFB to achieve a specified error amplifier output voltage (ITH). 1778fb 3