PI2003-00-SOIG View Datasheet(PDF) - Vicor
Part Name
Description
Manufacturer
PI2003-00-SOIG Datasheet PDF : 16 Pages
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Functional Description:
The PI2003 Cool-ORing controller IC is designed to
drive single or paralleled N-channel MOSFETs in
Active ORing applications, and optimized for -48V
applications. The PI2003 used with an external
MOSFET can function as an ideal ORing diode in
low side of a redundant power system, significantly
reducing power dissipation and eliminating the need
for heatsinking.
An N-channel MOSFET in the conduction path offers
extremely low on-resistance resulting in a dramatic
reduction of power dissipation versus the
performance of a diode used in conventional ORing
applications. This can allow for the elimination of
complex heat sinking and other thermal
management requirements. While the gate remains
above the gate threshold voltage it will allow current
to flow in the forward and reverse direction. Ideal
ORing applications do not allow for reverse current
flow, so the controller detect reverse current caused
by input power source failures and turn off the the
MOSFET as quickly as possible. Once the gate
voltage falls below the gate threshold, the MOSFET
is off and the body diode will be reverse biased
preventing reverse current flow and subsequent
excessive voltage droop on the redundant bus.
During forward over-current conditions the controller
maintains gate drive to keep the MOSFET forward
drop and power dissipation as low as possible.
While conventional ORing solutions using diodes
offer no protection against forward over-current
conditions. The PI2003 will provide an active-low
fault flag to the system via the FT pin. The fault flag
is also issued during the reverse current condition,
and light load or shorted MOSFET conditions.
Differential Amplifier:
The PI2003 integrates a high-speed low offset
voltage differential amplifier to sense the difference
between the Sense Positive (SP) pin voltage and
Sense Negative (SN) pin voltage with high accuracy.
The amplifier output is connected to three
comparators: Reverse comparator, Forward
comparator, and Forward over-current comparator.
Reverse Current Comparator: RVS
The reverse current comparator provides the most
critical function in the controller, detecting negative
voltage caused by reverse current. When the SN
pin is 6mV higher than the SP pin, the reverse
comparator will enable the gate discharge circuit and
turn off the MOSFETs in typically 160ns.
The reverse comparator has typically 3mV of
hysteresis referenced to SP-SN.
Forward Voltage Comparator: FWD
The FWD comparator detects when a forward
current condition exists and SP is 6mV(typical)
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 150mV(typical) higher
than SN. When the GATE output voltage is greater
than 50% of the VC voltage and SP-SN is higher
than 150mV, the PI2003 will initiate a fault condition
via the FT pin.
VC and Internal Voltage Regulator:
The PI2003 has a separate input (VC) that provides
power to the control circuitry and the gate driver. An
internal regulator clamps the VC voltage (VVC-CLM ) to
11V.
VC may be tied to a voltage higher than VVC-CLM
through a resistor to limit VC current.
The internal regulator circuit has a comparator to
monitor VC voltage and initiates a FAULT condition
when VC is lower than the VC Under-Voltage
Threshold, 7.15V
Gate Driver:
The gate driver (GATE) output is configured to drive
an external N-channel MOSFET. In the high state,
the gate driver applies a 150µA current source to the
MOSFET gate limited to the VC voltage.
When a reverse current fault is initiated, the gate
driver pulls the GATE pin low and discharges the
FET gate with 4 Apeak capability.
When the input source voltage is applied before the
MOSFET is fully enhanced, a voltage greater than
the Forward Over Current (FOC) Threshold may be
present across the MOSFET. To avoid an erroneous
FOC detection, a VGS detector blanks the FOC and
FWD comparators from initiating a fault, until the
GATE pin reaches 50% of VC pin voltage.
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 and VG > ½ VC
Picor Corporation • picorpower.com
PI2003
Rev 1.0
Page 5 of 16
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