Datasheet LTC1624 (Analog Devices) - 4

LTC1624
W U TYPICAL PERFORMANCE CHARACTERISTICS ITH/RUN Pin Source Current vs VITH vs Output Current I Temperature
ITH
ITH vs VITH
µA) /RUN PIN SOURCE CURRENT WITH V 200 300 5 2.4 = 1V ( ITH 250 4 200 ITH/RUN = 1V 150 3 µA) ( ITH/RUN = 0V /RUN (V) ACTIVE 150 MODE ITH I ITH 2 V 50 100 1.2 ACTIVE ITH 0.8 1 MODE 50 = 0V ( SHUTDOWN SHUTDOWN 0 3 /RUN PIN SOURCE CURRENT WITH V 0 µ 0 A) 0 I 0 OUT(MAX) I 0 0.8 1.2 2.4 I TH –40 –15 10 35 60 85 110 135 IOUT VITH (V) TEMPERATURE (°C)
(a) (b)
1624 G01 1624 G14 1624 G02
Operating Frequency vs Maximum Current Sense Frequency vs Feedback Voltage Temperature Threshold vs Temperature
250 250 170 168 VOUT IN REGULATION 200 200 166 164 150 150 162 160 100 100 158 FREQUENCY (kHz) FREQUENCY (kHz) 156 50 50 154 VFB = 0V CURRENT SENSE THRESHOLD (mV) 152 0 0 150 0 0.25 0.50 0.75 1.00 1.25 –40 –15 10 35 60 85 110 135 –40 –15 10 35 60 85 110 135 FEEDBACK VOLTAGE TEMPERATURE (°C) TEMPERATURE (°C) 1624 G03 1448 G12 1448 G13
U U U PIN FUNCTIONS SENSE – (Pin 1):
Connects to the (–) input for the current shutdown all functions are disabled and TG pin is held low. comparator. Built-in offsets between the SENSE – and VIN
V
pins in conjunction with R
FB (Pin 3):
Receives the feedback voltage from an exter- SENSE set the current trip thresh- nal resistive divider across the output. olds. Do not pull this pin more than 15V below VIN or more than 0.3V below ground.
GND (Pin 4):
Ground. Connect to the (–) terminal of COUT, the Schottky diode and the (–) terminal of C
I
IN.
TH/RUN (Pin 2):
Combination of Error Amplifier Compen- sation Point and Run Control Inputs. The current com-
SW (Pin 5):
Switch Node Connection to Inductor. In step- parator threshold increases with this control voltage. down applications the voltage swing at this pin is from a Nominal voltage range for this pin is 1.19V to 2.4V. Forcing Schottky diode (external) voltage drop below ground to this pin below 0.8V causes the device to be shut down. In VIN. 4