Datasheet LT1308A, LT1308B (Analog Devices) - 6

LT1308A/LT1308B
PIN FUNCTIONS (SO/TSSOP) VC (Pin 1/Pin 1):
Compensation Pin for Error Amplifi er.
SW (Pin 5/Pins 8, 9, 10):
Switch Pins. Connect induc- Connect a series RC from this pin to ground. Typical values tor/diode here. Minimize trace area at these pins to keep are 47kΩ and 100pF. Minimize trace area at VC. EMI down. For the TSSOP package, connect all SW pins together at the package.
FB (Pin 2/Pin 2):
Feedback Pin. Reference voltage is 1.22V. Connect resistive divider tap here. Minimize trace
VIN (Pin 6/Pins 11, 12):
Supply Pins. Must have local area at FB. Set VOUT according to: bypass capacitor right at the pins, connected directly to ground. For the TSSOP package, connect both V V IN pins OUT = 1.22V(1 + R1/R2). together at the package.
SHDN (Pin 3/Pin 3):
Shutdown. Ground this pin to turn
LBI (Pin 7/Pin 13):
Low-Battery Detector Input. 200mV off switcher. To enable, tie to 1V or more. SHDN does reference. Voltage on LBI must stay between –100mV not need to be at VIN to enable the device. and 1V. Low-battery detector does not function with
GND (Pin 4/Pins 4, 5, 6, 7):
Ground. Connect directly SHDN pin grounded. Float LBI pin if not used. to local ground plane. Ground plane should enclose all
LBO (Pin 8/Pin 14):
Low-Battery Detector Output. Open components associated with the LT1308. PCB copper collector, can sink 50μA. A 220kΩ pull-up is recommend- connected to these pins also functions as a heat sink. For ed. LBO is high impedance when SHDN is grounded. the TSSOP package, connect all pins to ground copper to get the best heat transfer. This keeps chip heating to a minimum. 1308abfb 6