lt3470a Linear Technology Corporation, lt3470a Datasheet - Page 7

• Manufacturer Part Number: lt3470a
• Description: Micropower Buck Regulator With Integrated Boost And Catch Diodes
• Manufacturer: Linear Technology Corporation

PIN FUNCTIONS
SHDN (Pin 8): The SHDN pin is used to put the LT3470A in
shutdown mode. Tie to ground to shut down the LT3470A.
Apply 2V or more for normal operation. If the shutdown
feature is not used, tie this pin to the V
NC (Pin 7): This pin can be left fl oating, connected to V
or tied to GND.
V
internal regulator and to the internal power switch. This
pin must be locally bypassed.
GND (Pin 5): Tie the GND pin to a local ground plane
below the LT3470A and the circuit components. Return
the feedback divider to this pin.
SW (Pin 4): The SW pin is the output of the internal power
switch. Connect this pin to the inductor, catch diode and
boost capacitor.
IN
(Pin 6): The V
IN
pin supplies current to the LT3470A’s
IN
pin.
IN
,
BOOST (Pin 3): The BOOST pin is used to provide a drive
voltage, which is higher than the input voltage, to the
internal bipolar NPN power switch.
BIAS (Pin 2): The BIAS pin connects to the internal boost
Schottky diode and to the internal regulator. Tie to V
when V
BIAS pin will supply current to the internal regulator.
FB (Pin 1): The LT3470A regulates its feedback pin to
1.25V. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
+ R1/R2) or R1 = R2 (V
Exposed Pad (Pin 9): Ground. Must be soldered to PCB.
OUT
> 2.5V or to V
IN
OUT
otherwise. When V
/1.25 – 1).
LT3470A
OUT
BIAS
= 1.25V (1
> 3V the
3470af
7
OUT