Datasheet LTC1772 (Analog Devices) - 3

LTC1772
ELECTRICAL CHARACTERISTICS Note 1:
Absolute Maximum Ratings are those values beyond which the life Operation at high junction temperatures degrades operating lifetimes. of a device may be impaired. Operating lifetimes at junction temperatures greater than 125°C is derated
Note 2:
The LTC1772E is guaranteed to meet specifications from 0°C to to 1000 hours. 70°C. Specifications over the –40°C to 85°C operating temperature range
Note 4:
Dynamic supply current is higher due to the gate charge being are assured by design, characterization and correlation with statistical delivered at the switching frequency. process controls. The LTC1772I is guaranteed to meet specified
Note 5:
The LTC1772 is tested in a feedback loop that servos VFB to the performance from –40°C to 85°C. The LTC1772H is guaranteed to meet output of the error amplifier. specified performance from –40°C to 140°C.
Note 6:
Peak current sense voltage is reduced dependent on duty cycle to
Note 3:
TJ is calculated from the ambient temperature TA and power a percentage of value as given in Figure 2. dissipation PD according to the following formula: TJ = TA + (PD • θJA°C/W)
W U TYPICAL PERFOR A CE CHARACTERISTICS Reference Voltage Normalized Frequency Undervoltage Lockout Trip vs Temperature vs Temperature Voltage vs Temperature
825 10 2.14 VIN = 4.2V VIN = 4.2V VIN FALLING 820 8 2.10 815 6 2.06 810 4 2.02 805 2 1.98 800 0 1.94 VOLTAGE (mV) 795 –2 1.90 FBV TRIP VOLTAGE (V) 790 –4 1.86 785 NORMALIZED FREQUENCY (%) –6 1.82 780 –8 1.78 775 –10 1.74 –55 –35 –15 5 25 45 65 85 105 125 145 –55 –35 –15 5 25 45 65 85 105 125 145 –55 –35 –15 5 25 45 65 85 105 125 145 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1772 G01 1772 G02 1772 G03
Maximum (VIN – SENSE–) Voltage Shutdown Threshold vs Duty Cycle vs Temperature
130 550 VIN = 4.2V VIN = 4.2V 120 TA = 25°C 510 470 110 430 100 390 90 350 80 310 TRIP VOLTAGE (mV) TRIP VOLTAGE (V) 270 70 230 60 190 50 150 20 30 40 50 60 70 80 90 100 –55 –35 –15 5 25 45 65 85 105 125 145 DUTY CYCLE (%) TEMPERATURE (°C) 1772 G04 1772 G05 1772fb 3