Datasheet LT3479 (Analog Devices) - 5

LT3479
PIN FUNCTIONS (DFN/TSSOP) SW (Pins 1, 2/Pins 1, 2):
Switch Pins. Collector of the
FBP (Pin 9/Pin 10):
The Noninverting Input to the Error internal NPN power switch. Connect the inductor and diode Amplifi er. Connect resistive divider tap here for negative here and minimize the metal trace area connected to this output voltage. pin to minimize electromagnetic interference.
FBN (Pin 10/Pin 11):
The Inverting Input to the Error
L (Pin 3/Pin 3):
Inductor Pin. Connect the inductor to Amplifi er. Connect resistive divider tap here for positive this pin. output voltage.
VS (Pin 4/Pin 4):
Inductor Supply. Must be locally bypassed.
VC (Pin 11/Pin 12):
Compensation Pin for Error Amplifi er. Powers the switch and the inductor. In case only one supply Connect a series RC from this pin to GND. Typical values voltage is available, tie VIN and VS together. are 10kΩ and 2.2nF.
VIN (Pin 5/Pin 5):
Input Supply. Must be locally bypassed.
SS (Pin 12/Pin 13):
Soft-Start. Place a soft-start capacitor Powers the internal control circuitry. here. Leave fl oating if not in use.
RT (Pin 6/Pin 6):
Timing Resistor Pin. Adjusts the switch-
GND (Pins 13, 14/Pins 8, 14, 15, 16):
Ground. Tie directly ing frequency. Do not leave this pin open. See Table 4 for to local ground plane. RT values and switching frequencies.
Exposed Pad (Pin 15/Pin 17):
Power Ground. Must be
SHDN (Pin 7/Pin 7):
Shutdown. Tie to 1.5V or greater to connected to electrical PCB ground. enable the device. Tie below 0.3V to turn off the device.
VREF (Pin 8/Pin 9):
Bandgap Voltage Reference. Internally set to 1.235V. Connect this pin to FBP if generating a posi- tive output, or to an external resistor divider if generating a negative voltage. This pin can provide up to 100μA of current and can be locally bypassed with a 100pF capacitor. 3479fc 5