PI2007 datasheet(14/19 Pages) VICOR

14 / 19 page



Picor Corporation • picorpower.com

PI2007

Rev 1.3

Page 14 of 19

Typical application Example 2:

Requirement:

+48V High Side Redundant

Bus Voltage = +48V (+36V to +60V, 100V for 100ms

transient)

Load Current = 5A load (assume through each

redundant path)

Maximum Ambient Temperature = 60°C

Solution:

A single PI2007 with a suitable MOSFET for each

redundant +48V power source should be used and

configured as shown in Figure 17 or Figure 18. Figure

17 is configured with the VC biased from the return

line through a bias resistor. Figure 18 is configured

with the VC biased from the return line through the

constant current circuit.

Select a suitable N-Channel MOSFET:

Select the

N-Channel MOSFET with voltage rating higher than

the input voltage, Vin, plus any expected transient

voltages, with a low RDS(on) that is capable of

supporting the full load current with margin. For

instance, a 100V rated MOSFET with 10A current

capability is suitable. An exemplary MOSFET having

these characteristic is IRF7853PbF from International

Rectifier.

From the IRF7853PbF datasheet:

N-Channel MOSFET

VDS= 100V

ID = 8.3A maximum continuous drain current at

25°C

ID-PULSE = 66A pulsed drain current

VGS(MAX) =

 20V

RθJA= 50°C/W on 1in

2 copper, t ≤ 10seconds

RθJA for continuous operation not provided

RDS(on)=14.4mΩ typical at VGS=10V, TJ=25°C

RDS(on)=18mΩ maximum at VGS=10V, TJ=25°C

Reverse current threshold is:

reverse

Vth

reverse

333

)

(











Power dissipation:

Rds(on) is 18mΩ maximum at 25°C & 10Vgs and will

increase as the temperature increases. Add 20°C to

maximum ambient temperature to compensate for the

temperature rise due to power dissipation. At 80°C

(60°C + 20°C) Rds(on) will increase by 40%.











)

(

maximum at 80°C

Maximum Junction temperature





























)

(

max

Recalculate maximum RDS(on) at 95°C.

At 95°C Rds(on) will increase by 50%:











)

(

maximum at 95°C

Maximum Junction temperature after 10s





























)

(

max

For continuous operation refer the MOSFET

datasheet for RθJA under continuous operation and

plug it in place of 50°C/W.

VC Bias: Since the bus voltage is higher than 14V,

connect VC pin to the high side of the input voltage

and connect a bias resistor (RPG) or a constant current

circuit between PI2007 SGND pin and ground (Vin

return), as shown in Figure 17 and Figure 18. Place a

low forward voltage drop Schottky diode and a 1μF

ceramic capacitor between SGND pin and VC pin.

Also connect PGND pin to SGND at the coupling

capacitor terminal.

Recommended Schottky: PMEG3005AEA from NXP

or equivalent

RPG selection:



















Max

CLMMax

min

Select RPG=11kΩ 1%

RPG maximum power dissipation:





PdR

CLMMin

218

)

(

max















Use ¼ W Resistor in 1206 package

Figure 17: PI2007 in high side +48V application, VC

is biased through a bias resistor

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