LTC4215-2_15 Datasheet, PDF (9/28 Pages) Linear Technology – Hot Swap Controller with I2C Compatible Monitoring

LTC4215/LTC4215-2
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 (QFN Package): 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 cur-
rent source is required. Internally tied to SDAI in SSOP
package.
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. Internally tied to SDAO in
SSOP package.
SDA (SSOP Package): Serial Bus Data Input/Output Line.
Formed by internally tying the SDAO and SDAI lines to-
gether. An external pull-up resistor or current source is
required.
SENSE⁺ (QFN Package): 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. Internally
tied to V_DD in SSOP package.
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.
SS: Soft Start Input. Sets the inrush current slew rate at
start-up. Connect a 68nF capacitor to provide 5mV/ms as
the slew rate for the sense voltage in start-up. This cor-
responds to 1A/ms with a 5mΩ sense resistor. Note that
a large soft-start capacitor and a small TIMER capacitor
may result in a condition where the timer expires before
the inrush current has started. Allow an additional 10nF
of timer capacitance per 1nF of soft-start capacitor to
ensure proper start-up. Use 1nF minimum to ensure an
accurate inrush current.
TIMER: Start-Up Timer Input. Connect a capacitor be-
tween 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. Allow an additional 10nF of
timer capacitance per 1nF of soft-start (SS) capacitor to
ensure proper start-up. The minimum value for the TIMER
capacitor is 10nF.
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.
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