5

LTC3408

3408f

Output Ripple Waveform

Load Step Response

REF Transient

10mV/DIV

100mA/DIV

200ns/DIV

3408 G16

100mV/DIV

500mA/DIV

500mA/DIV

20

µs/DIV

3408 G17

0

1.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

3408 G19

0.5

1.5

PI FU CTIO S

resistive divider divides the output voltage down by 3 for

comparison to the external reference voltage. The drain of

the P-channel bypass MOSFET is connected to this pin.

coupled to GND, Pin 3, with a 10

µF or greater ceramic

capacitor.

GND (Pin 3): Ground Pin.

SW (Pin 4): Switch Node Connection to Inductor. This pin

connects to the drains of the internal main and synchro-

nous power MOSFET switches.

RUN (Pin 5): Run Control Input. Forcing this pin above

1.5V enables the part. Forcing this pin below 0.3V shuts

down the device. In shutdown, all functions are disabled

drawing <1

µA supply current. Do not leave RUN floating.

REF (Pin 6): External Reference Input. Controls the output

voltage to 3

× the applied voltage at REF. Also turns on the

Exposed Pad (Pin 9): Connect to GND, Pin 3.

0.5V/DIV

1V/DIV

40

µs/DIV

3408 G18