Datasheet

LTC4280
9
4280f
PIN FUNCTIONS
SCL: Serial Bus Clock Input. Data at the SDA pin is shifted
in or out on rising edges of SCL. This is a high impedance
pin that is generally driven by an open-collector output
from a master controller. An external pull-up resistor or
current source is required.
SDAO: Serial Bus Data Output. Open-drain output for
sending data back to the master controller or acknowledging
a write operation. Normally tied to SDAI to form the SDA
line. An external pull-up resistor or current source is
required.
SDAI: Serial Bus Data Input. A high impedance input for
shifting in address, command or data bits. Normally tied
to SDAO to form the SDA line.
SENSE
+
: Positive Current Sense Input. Connect this pin to
the input of the current sense resistor. Must be connected
to the same trace as V
DD
.
SENSE
–
: Negative Current Sense Input. Connect this pin to
the output of the current sense resistor. This pin provides
sense voltage feedback and monitoring for the current
limit, circuit breaker and ADC.
SOURCE: N-Channel MOSFET Source and ADC Input.
Connect this pin to the source of the external N-channel
MOSFET switch for gate drive return. This pin also serves as
the ADC input to monitor output voltage. The pin provides
a return for the gate pulldown circuit.
TIMER: Start-Up Timer Input. Connect a capacitor
between this pin and ground to set a 12.3ms/µF duration
for start-up, after which an overcurrent fault is logged if
the inrush is still current limited. The duration of the off
time is 600ms/µF when overcurrent auto-retry is enabled,
resulting in a 1:50 duty cycle. An internal timer provides
a 100ms start-up time and 5 seconds auto-retry time if
this pin is tied to INTV
CC
.
UV: Undervoltage Comparator Input. Connect this pin
to an external resistive divider from V
DD
. If the voltage
at this pin falls below 1.155V, an undervoltage fault is
detected and the GATE turns off. Pulling this pin below
0.4V resets all faults and allows the GATE to turn back on.
Tie to INTV
CC
if unused.
V
DD
: Supply Voltage Input. This pin has an undervoltage
lockout threshold of 2.84V and overvoltage lockout
threshold of 15.6V.