LTC3642 datasheet(6/20 Pages) LINER

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LTC3642

3642f

PIN FUNCTIONS

SW (Pin 1): Switch Node Connection to Inductor. This

pin connects to the drains of the internal power MOSFET

switches.

VIN (Pin 2): Main Supply Pin. A ceramic bypass capacitor

should be tied between this pin and GND (Pin 8).

ISET (Pin 3): Peak Current Set Input. A resistor from this

pin to ground sets the peak current trip threshold. Leave

ﬂoating for the maximum peak current (115mA). Short

this pin to ground for the minimum peak current (25mA).

A 1μA current is sourced out of this pin.

SS (Pin 4): Soft-Start Control Input. A capacitor to ground

at this pin sets the ramp time to full current output dur-

ing start-up. A 5μA current is sourced out of this pin. If

left ﬂoating, the ramp time defaults to an internal 0.75ms

soft-start.

RUN (Pin 5): Run Control Input. A voltage on this pin

above 1.2V enables normal operation. Forcing this pin

below 0.7V shuts down the LTC3642, reducing quiescent

current to approximately 3μA.

VOUT/VFB (Pin 6): Output Voltage Feedback. For the ﬁxed

output versions, connect this pin to the output supply. For

the adjustable version, an external resistive divider should

be used to divide the output voltage down for comparison

to the 0.8V reference.

HYST (Pin 7): Run Hysteresis Open-Drain Logic Output.

This pin is pulled to ground when RUN (Pin 5) is below

1.2V. This pin can be used to adjust the RUN pin hysteresis.

See Applications Information.

GND (Pin 8): Chip Ground.

Exposed Pad (Pin 9):

Ground. Must be soldered to PCB

ground for optimal electrical and thermal performance.

LTC3642 Datasheet(PDF) 6 Page - Linear Technology