Datasheet LTC1871X (Analog Devices) - 4

LTC1871X
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = VINTVCC = 5V, VRUN = 1.5V, RFREQ = 80k, VMODE/SYNC = 0V, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
fSYNC/fOSC Recommended Maximum Synchronized fOSC = 300kHz (Note 6) 1.25 1.30 Frequency Ratio fOSC = 300kHz (Note 6), (Note 2) l 1.25 1.30 tSYNC(MIN) MODE/SYNC Minimum Input Pulse Width VSYNC = 0V to 5V 25 ns tSYNC(MAX) MODE/SYNC Maximum Input Pulse Width VSYNC = 0V to 5V 0.8/fOSC ns VIL(MODE) Low Level MODE/SYNC Input Voltage 0.3 V (Note 2) l 0.3 V VIH(MODE) High Level MODE/SYNC Input Voltage 1.2 V (Note 2) l 1.2 V RMODE/SYNC MODE/SYNC Input Pull-Down Resistance 50 kΩ VFREQ Nominal FREQ Pin Voltage 0.62 V
Low Dropout Regulator
VINTVCC INTVCC Regulator Output Voltage VIN = 7.5V 5.0 5.2 5.4 V ∆VINTVCC INTVCC Regulator Line Regulation 7.5V ≤ VIN ≤ 15V 8 25 mV ∆VIN1 ∆VINTVCC INTVCC Regulator Line Regulation 15V ≤ VIN ≤ 30V 70 200 mV ∆VIN2 VLDO(LOAD) INTVCC Load Regulation 0 ≤ IINTVCC ≤ 20mA, VIN = 7.5V –2 –0.2 % VDROPOUT INTVCC Regulator Dropout Voltage VIN = 5V, INTVCC Load = 20mA 280 mV IINTVCC Bootstrap Mode INTVCC Supply Current in RUN = 0V, SENSE = 5V 10 20 μA Shutdown
GATE Driver
tr GATE Driver Output Rise Time CL = 3300pF (Note 7) 17 100 ns tf GATE Driver Output Fall Time CL = 3300pF (Note 7) 8 100 ns
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
The dynamic input supply current is higher due to power MOSFET may cause permanent damage to the device. Exposure to any Absolute gate charging (QG • fOSC). See Applications Information. Maximum Rating condition for extended periods may affect device
Note 5:
The LTC1871X is tested in a feedback loop which servos VFB to reliability and lifetime. the reference voltage with the ITH pin forced to the midpoint of its voltage
Note 2:
The LTC1871X is guaranteed over the full –40°C to 175°C range (0.3V ≤ VITH ≤ 1.2V, midpoint = 0.75V). operating junction temperature range. High junction temperatures degrade
Note 6:
In a synchronized application, the internal slope compensation operating lifetimes. Operating lifetime is derated at junction temperatures gain is increased by 25%. Synchronizing to a significantly higher ratio will greater than 125°C. reduce the effective amount of slope compensation, which could result in
Note 3:
TJ is calculated from the ambient temperature TA and power subharmonic oscillation for duty cycles greater than 50%. dissipation PD according to the following formula:
Note 7:
Rise and fall times are measured at 10% and 90% levels. TJ = TA + (PD • 120°C/W) 1871xf 4 For more information www.linear.com/LTC1871X Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Application Related Parts