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PI2121

Rev. 1.2 Page 13 of 21

Figure 18: Plot of PI2121 response time to reverse current detection (Example 1, Figure 22)

Application Information

The PI2121 is designed to replace ORing diodes in

high

current,

low

voltage

redundant

power

architectures. Replacing a traditional diode with a

PI2121 will result in significant power dissipation

reduction as well as board space reduction,

efficiency improvement and additional protection

features.

This section describes in detail the

procedure to follow when designing with the PI2121

Active ORing solution. Two Active ORing design

examples are presented.

Fault Indication:

The

FT output pin is an open collector and should

be pulled up to the logic voltage or to the controller

VC via a resistor (10KΩ).

Blanking Timer:

Connect the blanking timer pin (BK) to GND to

program the device for the fastest reverse

comparator response time of 160ns typical.

To

increase the blanking time, connect the BK pin to

GND via a resistor to avoid the fault response to

short reverse current pulses. Refer to the plot in the

Functional Description section for resistor values

versus the reverse blanking time.

Auxiliary Power Supply (Vaux):

Vaux is an independent power source required to

supply power to the VC input. The Vaux voltage

should be 5V higher than Vin (redundant power

source output voltage) to fully enhance the internal

MOSFET.

A bias resistor (Rbias) is required if Vaux is higher

than 15V. Rbias should be connected between the

VC pin and Vaux.

Minimize the resistor value for low Vaux voltage

levels to avoid a voltage drop that may reduce the

VC voltage lower than required to drive the gate of

the internal MOSFET.

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