LTC3642
PIN FUNCTIONS
SW (Pin 1): Switch Node Connection to Inductor. This
pin connects to the drains of the internal power MOSFET
switches.
V
/V (Pin 6): Output Voltage Feedback. For the fixed
OUT FB
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.
V (Pin 2): Main Supply Pin. A ceramic bypass capacitor
IN
should be tied between this pin and GND (Pin 8).
HYST (Pin 7): Run Hysteresis Open-Drain Logic Output.
This pin is pulled to ground when RUN (Pin 5) is below
1.2V.ThispincanbeusedtoadjusttheRUNpinhysteresis.
See Applications Information.
I
(Pin 3): Peak Current Set Input. A resistor from this
SET
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 1ꢀA current is sourced out of this pin.
GND (Pin 8): Chip Ground.
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 5ꢀA current is sourced out of this pin. If
left floating, the ramp time defaults to an internal 0.75ms
soft-start.
Exposed Pad (Pin 9): Ground. Must be soldered to PCB
ground for optimal electrical and thermal performance.
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 3ꢀA.
3642f
6
Linear [ Linear ]
