Datasheet LTC1871-1 (Analog Devices) - 6

LTC1871-1
TYPICAL PERFORMANCE CHARACTERISTICS Maximum Sense Threshold SENSE Pin Current Frequency vs Temperature vs Temperature vs Temperature
325 160 35 GATE HIGH 320 VSENSE = 0V 315 155 310 305 300 150 30 295 290 GATE FREQUENCY (kHz) 145 SENSE PIN CURRENT (μA) 285 MAX SENSE THRESHOLD (mV) 280 275 140 25 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 18711 G13 18711 G14 18711 G15
INTVCC Dropout Voltage INTVCC Load Regulation INTVCC Line Regulation vs Current, Temperature
5.4 500 VIN = 7.5V 450 150°C 5.2 400 125°C 350 5.3 75°C 300 25°C 250 VOLTAGE (V) VOLTAGE (V) CC 5.1 CC 200 0°C 5.2 INTV INTV 150 DROPOUT VOLTAGE (mV) –50°C 100 50 5.0 5.1 0 0 10 20 30 40 50 60 70 80 0 5 10 15 20 25 30 35 40 0 5 10 15 20 INTVCC LOAD (mA) VIN (V) INTVCC LOAD (mA) 18711 G16 18711 G17 18711 G18
PIN FUNCTIONS RUN (Pin 1):
The RUN pin provides the user with an
ITH (Pin 2):
Error Amplifi er Compensation Pin. The accurate means for sensing the input voltage and pro- current comparator input threshold increases with this gramming the start-up threshold for the converter. The control voltage. Nominal voltage range for this pin is 0V falling RUN pin threshold is nominally 1.248V and the to 1.40V. comparator has 100mV of hysteresis for noise immunity.
FB (Pin 3):
Receives the feedback voltage from the external When the RUN pin is below this input threshold, the IC resistor divider across the output. Nominal voltage for is shut down and the VIN supply current is kept to a low this pin in regulation is 1.230V. value (typ 10μA). The Absolute Maximum Rating for the voltage on this pin is 7V.
FREQ (Pin 4):
A resistor from the FREQ pin to ground programs the operating frequency of the chip. The nominal voltage at the FREQ pin is 0.6V. 18711fb 6