PI2126 datasheet(10/15 Pages) VICOR

10 / 15 page

Picor Corporation • picorpower.com

PI2126

Rev 1.1

Page 10 of 15

Application Information

The PI2126 is designed to replace high side ORing diodes in

high

current

low

voltage

bus

redundant

power

architectures. Replacing a traditional diode with a PI2126

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 PI2126 Active ORing solution.

Control Circuitry Bias:

The PI2126 control circuitry and the gate driver for the

internal MOSFET are biased through the VC pin or VR pin.

An internal regulator clamps the VC voltage (VVC-PG) to

11.7V typically. An internal bypass ceramic capacitor

(0.1μF) is connected between VC and PG to hold VVC-PG

steady.

In 12V system applications, where the input voltage (Vin) is

between 10V and 14V, connect the VR pin to Vin and

connect PG to the Vin return, Figure 1. A 420Ω internal

resistor (RBias) is connected between the VR pin and the VC

pin.

In high voltage applications above 14V, PG pin has to float

above ground and VC pin will be connected directly to Vin.

As shown in Figure 17, VR pin is disconnected and PG pin

float on a bias resistor (RPG). A low current low forward

voltage drop Schottky diode is required for the PI2126

when PI2126 is configured floating on PG. Connect one

terminal of RPG to the PG pin and the other end of RPG to

ground (Vin return). Connect the Schottky diode anode to

the PG pin and connect its cathode to the VC pin.

Figure 17: PI2126 in application above 14V

Recommended Schottky Diode:

PMEG3005AEA: from NXP or equivalent

RPG selection for input voltage greater than 14V:

Select the resistor (RPG) value at the minimum input

voltage to avoid a voltage drop that may reduce VVC-PG

lower than VC under voltage lockout.

Select the value of RPG using the following equations:

And RPG maximum power dissipation is:

Where:

Minimum applied input voltage

Maximum applied input voltage

: Controller maximum Under-Voltage Rising

Threshold, 8.5V

: Controller maximum clamp voltage, 12.5V

Controller maximum bias current, use 2.0mA

0.1mA is added for margin

RPG calculation example

Vin (minimum) = 11V and Vin (maximum) = 18V

Select a lower typical resistor value (1KΩ) and calculate its

power dissipation.

Internal N-Channel MOSFET BVDSS:

The PI2126’s internal N-Channel MOSFET breakdown

voltage (BVDSS) is rated for 30V at 25°C and will degrade to

28V at -40°C, refer to Figure 8. Drain to source voltage

should not exceed BVDSS in nominal operation. During a

fast switching transient the MOSFET can tolerate voltages

higher than its BVDSS rating under avalanche conditions,

refer to the Absolute Maximum Ratings table.

In Active ORing applications when one of the input power

sources is shorted, a large reverse current is sourced from

PI2126

Vin1

PI2126

Vin2

RPG

PMEG3005AEA

RPG

PMEG3005AEA

EOL

PI2126 Datasheet(PDF) 10 Page - Vicor Corporation

PI2126 Datasheet(HTML) 10 Page - Vicor Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Datasheet Download

Link URL