PI2123 Datasheet, PDF (7/20 Pages) Vicor Corporation – 15 Volt, 15 Amp Full-Function Active ORing Solution

Forward Voltage Comparator: FWD
The FWD comparator detects when a forward
current condition exists and SP is 6mV positive with
respect to SN. When SP-SN is less than 6mV, the
FWD comparator will assert the Fault flag to report a
fault condition indicative of a light load or “load not
present” condition or possible shorted MOSFET.
Forward Over Current Comparator: FOC
The FOC comparator indicates an excessive forward
current condition when SP is 66mV (typical) higher
than SN. When the FET is in the on-state and SP-
SN is higher than 66mV (typical) the PI2123 will
initiate a fault condition via the FT pin.
Slave:
In high current applications that exceed the single
PI2123 current handling capability, multiple PI2123’s
can be paralleled and synchronized by using the
slave function.
The Slave function synchronizes multiple PI2123’s
together and allows for localized control of each
paralleled MOSFET. One PI2123 will be designated
as the master and it will control the response of the
slaved PI2123’s.
condition when VC is lower than the VC Under-
Voltage Threshold
UV:
The Under-Voltage (UV) input trip point can be
programmed through an external resistor divider to
monitor the input voltage. The UV comparator
initiates a fault condition and pulls the FT pin low,
when UV falls below the Under-Voltage Falling
Threshold. If the PI2123 is configured in a floating
application, where the GND pin is connected to the
input voltage, the UV pin cannot detect the input
voltage. In this case, the UV pin should be disabled
by connecting it to the VC pin.
OV:
The Over-Voltage (OV) input trip point can be
programmed through an external resistor divider to
monitor the input voltage. The OV comparator
initiates a fault condition and pulls the FT pin low
when OV rises above the Over-Voltage Rising
Threshold. If the PI2123 is configured in a floating
application, where the GND pin is connected to the
input voltage, the OV pin cannot detect the input
voltage. In this case, the OV pin should be disabled
by connecting it to the control GND pin.
When the PI2123 is configured in the “Master Mode”
by connecting the BK to ground, the SL will be an
output having the same signal characteristics as the
internal Gate Driver. In this configuration, the
SL output is capable of driving up to ten PI2123’s,
configured in “Slave Mode”, through their
corresponding SL pins. Logic high for the SL pin is
limited to 5.5V (max).
When the BK pin is tied to VC, the PI2123 becomes
a slave and the SL pin will be an input. The internal
Gate driver section and reverse current section are
the only active circuits in the slaved PI2123 while the
master performs the diagnostics and gate drive
control.
VC and Internal Voltage Regulator:
The PI2123 has a separate input (VC) to provides
power to the controller circuitry and the internal gate
driver. An internal regulator clamps the VC voltage
to 15.5V.
For high side applications, the VC input should be at
least 6V above the bus voltage (Vin) to properly
enhance the internal N-channel MOSFET.
The internal regulator circuit has a comparator to
monitor the VC voltage and initiates a FAULT
Over-Temperature Detection:
The internal Over-Temperature block monitors the
junction temperature of the controller. The over-
temperature threshold is set to 160°C with -10°C of
hysteresis. When the controller temperature
exceeds this threshold, the over-temperature circuit
initiates a fault condition and pulls the FT pin low.
Fault:
The fault circuit output is an open collector with 40μs
delay to prevent any false triggering. The FT pin
will be pulled low when any of the following faults
occur:
• Reverse Current
• Forward Over-Current
• Forward Low Current
• Over-Temperature
• Input Under-Voltage
• Input Over-Voltage
• VC pin Under-Voltage
A gate voltage detector prevents FOC or FWD from
initiating a fault when the MOSFET is in an OFF
condition.
The only fault condition that initiates gate turn-off of
the MOSFET (as well as a fault flag signal) is when
the reverse current fault conditions are met. All other
fault conditions issue only a fault flag signal via the
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PI2123
Rev 1.0 Page 7 of 20