PI2001 Datasheet, PDF (18/23 Pages) Vicor Corporation – Universal Active ORing Controller IC

4. SP and SN pins: Since the PI2001 controller
GND pin is connected to the input (Vin) which is
also the MOSFET source, connect the SP pin
directly to the PI2001 GND pin to reduce the
parasitic between the SP pin and the GND pin to
avoid negative voltages on the SP pin with
respect to GND pin. Connect the SN pin to the
MOSFET drain pin.
5. BK pin: Connect the BK pin to the GND pin to
achieve the minimum reverse current response
time.
6. SL pin: Not required, so leave floating.
7. FT pin: The FT pin output is referenced to the
PI2001 GND pin which is connected to Vin. A
level shift circuit can be added to make the FT
pin output referenced to the system ground. The
recommended level shift circuit is shown in Figure
16, The level shift circuit uses a Dual Bias
Resistor Transistor circuit which is available as a
small device that contains two transistors and
their bias resistors, part number
NSBC114EPDXV6T1.
8. UV and OV inputs: In floating applications these
pins can not be used to monitor Vin. Connect UV
to the VC pin and OV to the GND pin to disable
their function.
Typical application Example 3:
Requirement:
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:
1. A single PI2001 with a suitable MOSFET for each
redundant -48V power source should be used and
configured as shown in figure 17. The VC is
biased from the return line through a bias resistor.
2. 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 Si4486EY
from Vishay Siliconix.
From Si4486EY datasheet:
• N-Channel MOSFET
• V_DS= 100V
• I_D = 23A continuous drain current at 125°C
• VGS(MAX) = ± 20V
• R_θJA= 50°C/W
• R_DS(on)=20mΩ typical at V_GS=10V, T_J=25°C
Reverse current threshold is:
Is.reverse = ^Vth.reverse = ^{− 6mV} = −300mA
Rds(on) 20mΩ
Power dissipation:
Rds(on) is 25mΩ maximum at 25°C & 10Vgs and will
increase as the temperature increases. Add 40°C to
maximum ambient temperature to compensate for the
temperature rise due to power dissipation. At 100°C
(60°C + 40°C) Rds(on) will increase by 63%.
Rds(on) = 25mΩ∗1.63 = 41mΩ maximum at 100°C
Maximum Junction temperature
T_J
max
=
60°C
+
⎜⎛
⎝
50°C
W
∗
(5.0
A)²
∗
41mΩ⎟⎞
⎠
=
111°C
Recalculate based on calculated Junction
temperature, 115°C.
At 115°C Rds(on) will increase by 72%.
Rds(on) = 25mΩ∗1.72 = 43mΩ maximum at 115°C
T_J
max
=
60°C
+
⎜⎛
⎝
50°C
W
∗
(5.0
A)²
∗
43mΩ⎟⎞
⎠
=
113°C
Picor Corporation • picorpower.com
PI2001
Rev 1.0 Page 18 of 23