PI2002 Datasheet, PDF (17/23 Pages) Vicor Corporation – Active ORing Controller IC with Load Disconnect Feature

Recalculate based on calculated Junction
temperature, 115°C.
At 115°C Rds(on) will increase by 32%.
Rds(on) = 3.5mΩ∗1.32 = 4.62mΩ
T_J
max
=
75°C
+
⎜⎛
⎝
40°C
W
∗
(15A)²
∗
4.62mΩ⎟⎞
⎠
=
116.5°C
3. Vaux: Make sure Vaux voltage is higher than Vin
(power source output) by the voltage required to
fully enhance the MOSFET. Minimum required
Vaux = Vin + Vgs + 0.5V = 3.3V + 4.5V + 0.5V =
8.3V. Since 8.3V is less than the 11V minimum
Aux supply voltage, there is sufficient voltage
available to drive the gate of the MOSFET.
4. SP and SN pins: Connect the SP pin to the
MOSFET drain pin at the input and the SN pin to
the MOSFET drain pin at the load side.
5. OCT pin: Connect 18nF capacitor between OCT
pin and the GND pin to achieve the maximum off
time after forward over-current condition occurs.
6. SCD pin: Connect the SCD pin to the GND pin
for fast MOSFET enhancement.
7. FT pin: Connect to the logic input and to the
logic power supply via a 10KΩ resistor.
8. Program UV and OV to monitor input voltage:
Program UV at 3.0V and OV at 3.6V
Use the three-resistor divider configuration:
I _Ra = 200μA
Ra = ^{V (UVTH )}
I _Ra
=
500mV
200μA
= 2.5kΩ
or
2.49kΩ 1%
Rb
=
Ra_{⎜⎜⎝⎛}
V
V
(OV
(UV
)
)
− 1_{⎟⎟⎠⎞}
=
2.49kΩ⎜⎛
⎝
3.6V
3.0V
− 1⎟⎞
⎠
= 498Ω
or 499Ω 1%
Rc
=
(Ra
+
Rb
)_{⎜⎜⎝⎛}
V (UV )
V (UV_TH
)
−
1_{⎟⎟⎠⎞}
= (2.49kΩ
+
499Ω)⎜⎛
⎝
3.0V
500mV
− 1⎟⎞ = 14.95kΩ
⎠
or 15kΩ 1%
Figure 19: High side Active ORing function.
Figure 20: PI2002 performance in example 1, applied short at Vin1.
Picor Corporation • picorpower.com
PI2002
Rev1.1 Page 17 of 23