PI2002 View Datasheet(PDF) - Unspecified
Part Name
Description
MFG CO.
'PI2002' PDF : 23 Pages View PDF
I Ra
: Ra current.
Alternatively, a two-resistor voltage divider
configuration can be used and is shown in (Figure 18).
Figure 18: Two-resistor divider configuration
The UV resistor voltage divider can be obtained from
the following equations:
R1UV
= V (UVTH )
I RUV
Set R1UV value based on system allowable current
I RUV ≥ 100μA
R 2UV
=
R1UV
⎜⎜⎝⎛
V (UV )
V (UVTH
)
− 1⎟⎟⎠⎞
Where:
V (UVTH ) : UV threshold voltage
I RUV
: R1UV current
R1UV
= V (UVTH )
I RUV
Set R1OV value based on system allowable current
I RUV ≥ 100μA
R 2 OV
=
R1OV
⎜⎜⎝⎛
V (OV )
V (OVTH
)
−1⎟⎟⎠⎞
Where:
V (OVTH ) : OV threshold voltage
I ROV
: R1OV current
Typical application Example 1:
High Side Active ORing:
Requirement:
Redundant Bus Voltage = 3.3V
Load Current = 15A (assume through each redundant
path)
Maximum Ambient Temperature = 75°C
Auxiliary Voltage = 12V (11V to 13V)
Solution:
1. A single PI2002 with two suitable external
MOSFETs for each redundant 3.3V power source
should be used, configured as shown in the circuit
schematic in Figure 19
2. Select a suitable N-Channel MOSFET: Most
industry standard MOSFETs have a Vgs rating of
+/-12V or higher. Select an N-Channel MOSFET
with a low Rds(on) which is capable of supporting
the full load current with some margin, so a
MOSFET capable of at least 18A in steady state
is reasonable. An exemplary MOSFET having
these characteristic is FDS6162N7 from Fairchild.
From FDS6162N7 datasheet:
• N-Channel MOSFET
• VDS= 20V
• ID = 23A continuous drain current
• VGS(MAX)= ± 12V
• RθJA= 40°C/W
• RDS(on)=2.9mΩ typical at ID=23A, VGS≥4.5V,
TJ=25°C
Reverse current threshold is:
I RVS
=
VRVS −TH
2 * Rds(on)
=
− 6mV
2 * 2.9mΩ
=
−1.03A
Forward over-current threshold is:
I FOC
=
V FOC −TH
2 * Rds(on)
=
114mV
2 * 2.9mΩ
= 19.66A
Power dissipation final junction temperature for
each MOSFET:
Rds(on) is 3.5mΩ maximum at 25°C & 4.5Vgs and will
increase as the temperature increases. Add 25°C to
maximum ambient temperature to compensate for the
temperature rise due to power dissipation. At 100°C
(75°C + 25°C) Rds(on) will increase by 28%.
Rds(on) = 3.5mΩ∗1.28 = 4.48mΩ maximum at 100°C
Trise= RthJA ∗ Is2 ∗ Rds(on)
Maximum Junction temperature
TJ max = TA +Trise
TJ
max
=
75°C
+
⎜⎛
⎝
40°C
W
∗
(15A)2
∗
4.48mΩ⎟⎞
⎠
=
115°C
Picor Corporation • picorpower.com
PI2002
Rev1.1 Page 16 of 23
Share Link: 
