lt3470its8-trpbf Linear Technology Corporation, lt3470its8-trpbf Datasheet - Page 6

• Manufacturer Part Number: lt3470its8-trpbf
• Description: Micropower Buck Regulator With Integrated Boost And Catch Diodes
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
TYPICAL PERFOR A CE CHARACTERISTICS
SHDN (Pin 1/Pin 8): The SHDN pin is used to put the
LT3470 in shutdown mode. Tie to ground to shut down the
LT3470. Apply 2V or more for normal operation. If the
shutdown feature is not used, tie this pin to the V
NC (Pin 2/Pin 7): This pin can be left floating or connected
to V
V
LT3470’s internal regulator and to the internal power
switch. This pin must be locally bypassed.
GND (Pin 4/Pin 5): Tie the GND pin to a local ground plane
below the LT3470 and the circuit components. Return the
feedback divider to this pin.
SW (Pin 5/Pin 4): The SW pin is the output of the internal
power switch. Connect this pin to the inductor, catch diode
and boost capacitor.
LT3470
6
IN
600
800
700
500
400
300
200
100
900
U
0
IN
(Pin 3/Pin 6): The V
0
Boost Diode Forward Voltage
.
U
BOOST DIODE CURRENT (mA)
50
100
U
(ThinSOT/DD)
IN
150
W
pin supplies current to the
3470 G17
U
200
6.0
5.5
5.0
4.5
4.0
3.5
3.0
Minimum Input Voltage, V
0
T
A
= 25°C
IN
pin.
50
LOAD CURRENT (mA)
V
V
IN
IN
TO START
TO RUN
100
BOOST (Pin 6/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 7/Pin 2): The BIAS pin connects to the internal
boost Schottky diode and to the internal regulator. Tie to
V
3V the BIAS pin will supply current to the internal
regulator.
FB (Pin 8/Pin 1): The LT3470 regulates its feedback pin
to 1.25V. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
(1 + R1/R2) or R1 = R2 (V
Exposed Pad (DD, Pin 9): Ground. Must be soldered
to PCB.
OUT
when V
150
OUT
3470 G18
= 3.3V
OUT
200
> 2V or to V
8
7
6
5
4
0
Minimum Input Voltage, V
T
A
OUT
= 25°C
IN
/1.25 – 1).
otherwise. When V
50
LOAD CURRENT (mA)
V
V
IN
IN
TO START
TO RUN
100
OUT
150
OUT
= 1.25V
BIAS
= 5V
3470 G19
3470fc
200
>