Datasheet LT3470 (Analog Devices) - 6

LT3470
Typical perForMance characTerisTics Boost Diode Forward Voltage Minimum Input Voltage, VOUT = 3.3V Minimum Input Voltage, VOUT = 5V
900 6.0 8 TA = 25°C T V A = 25°C 800 IN TO START V 5.5 IN TO START 700 7 (V) 600 5.0 F 500 4.5 6 400 VIN TO RUN SCHOTTKY V 300 INPUT VOLTAGE (V) 4.0 V INPUT VOLTAGE (V) IN TO RUN 5 200 3.5 100 0 3.0 4 0 50 100 150 200 0 50 100 150 200 0 50 100 150 200 BOOST DIODE CURRENT (mA) LOAD CURRENT (mA) LOAD CURRENT (mA) 3470 G17 3470 G18 3470 G19
pin FuncTions (ThinSOT/DD) SHDN (Pin 1/Pin 8):
The SHDN pin is used to put the
BOOST (Pin 6/Pin 3):
The BOOST pin is used to provide LT3470 in shutdown mode. Tie to ground to shut down a drive voltage, which is higher than the input voltage, to the LT3470. Apply 2V or more for normal operation. If the the internal bipolar NPN power switch. shutdown feature is not used, tie this pin to the VIN pin.
BIAS (Pin 7/Pin 2):
The BIAS pin connects to the internal
NC (Pin 2/Pin 7):
This pin can be left floating or connected boost Schottky diode and to the internal regulator. Tie to to VIN. VOUT when VOUT > 2V or to VIN otherwise. When VBIAS >
V
3V the BIAS pin will supply current to the internal regulator.
IN (Pin 3/Pin 6):
The VIN pin supplies current to the LT3470’s internal regulator and to the internal power
FB (Pin 8/Pin 1):
The LT3470 regulates its feedback pin switch. This pin must be locally bypassed. to 1.25V. Connect the feedback resistor divider tap to this
GND (Pin 4/Pin 5):
Tie the GND pin to a local ground plane pin. Set the output voltage according to VOUT = 1.25V below the LT3470 and the circuit components. Return the (1 + R1/R2) or R1 = R2 (VOUT/1.25 – 1). feedback divider to this pin.
Exposed Pad (DD, Pin 9):
Ground. Must be soldered to
SW (Pin 5/Pin 4):
The SW pin is the output of the internal PCB. power switch. Connect this pin to the inductor, catch diode and boost capacitor. 3470fd 6 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 Typical Applications Package Description Revision History Related Parts