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
PI2161
®
Cool-Switch Series
60 Volt, 12 Amp Full-Function Load Disconnect Switch Solution
Description
®
The Cool-Switch PI2161 is a complete full-function
Load Disconnect Switch solution for medium voltage
applications with a high-speed electronic circuit
breaker and a very low on-state resistance
MOSFET. It is designed to protect an input power
bus from output load fault conditions. The PI2161
Cool-Switch solution is offered in an extremely small,
thermally enhanced 7mm x 8mm LGA package. The
PI2161 enables an extremely low power loss
solution with fast dynamic response to an over
current fault or EN high conditions. The PI2161
senses a small portion of the total MOSFET current
and has a low voltage threshold allowing the use of
low power sense resistors.
The switch is closed when the EN input is low and
is open when EN is high. Once enabled, the PI2161
monitors the MOSFET current through a sense
resistor. If an over current level is sensed, the switch
is quickly latched off to prevent the power source
from being overloaded. Bringing the EN pin high
will reset the over current latch allowing retry. The
PI2161 has an internal 10kΩ bias resistor connected
between the Drain (D) and VC to eliminate need for
external resistor in a 44V bus application (41V to
48V).
Features







Integrated High Performance 12A, 8.5mΩ
MOSFET
Very small, high density fully-optimized solution
with simple PCB layout
Programmable latching over-current detection
Fast 120ns disconnect response to load failures
Low loss current sensing
Fast disable via EN pin, typically 200ns.
Load Status output (VO scaled load voltage)
Applications




N+1 Redundant Power Systems
Servers & High End Computing
Load Disconnect
High Side Circuit Breaker
Package Information
The PI2161 is offered in the following package:
 17-pin 7mm x 8mm thermally enhanced LGA
package, achieving <10°C/W RθJ-PCB
Typical Application:
Figure 1: PI2161 High Side Disconnect switch
Picor Corporation • picorpower.com
Figure 2: PI2161 response time to output short fault
condition
PI2161
Rev1.1, Page 1 of 18

Pin Description
Pin Name
Pin
Number
EN
1
Enable: Logic level input, active low allows switch to reach 8.5mΩ typical in the on state
within 2ms. A logic high input will turn the switch off in typically 200ns. Leave this pin open
to allow switch to turn on after application of input power.
VO
2
Load Status Output: This pin pulls to the load voltage once the switch is enabled through
an internal 150kΩ resistor. Connect a resistor from this pin to ground to scale the load
voltage to the appropriate logic or analog level. Ground this pin if unused.
VC
3
Voltage Bias: This pin is the supply pin for the control circuitry and gate driver. Connect a
0.1μF capacitor between the VC pin and the PG pin. Voltage on this pin is regulated to
11.7V with respect to PG by an internal shunt regulator. A 10kΩ internal resistor (RD-VC) is
connected between D pin and VC pin.
PG
4
Control Circuitry Return: PG is the floating return path for the controller circuitry. Connect
this pin via a resistor to the GND (ground), as shown in Figure 1.
SP
5
Sense-Positive Input: Connect the SP pin to the SL pin side of the sense resistor as a
Kelvin connection. The magnitude of the voltage difference between SP and SN provides
an indication of the current through the sense resistor and the SL section of the MOSFET.
SL
6,7
Source Low: A low percentage of the internal N-channel MOSFET source current passes
through this to the sense resistor. Refer to the Current Sense section in the Functional
Description.
SN
8
Sense-Negative Input: Connect the SN pin to the SH pin side of the sense resistor as a
Kelvin connection. The magnitude of the voltage difference between SP and SN provides
an indication of the current through the sense resistor and the SL section of the MOSFET.
Description
SH
9, 10, 11, Source High: The Source of the internal N-channel MOSFET section providing the majority
17
of the load current and alternate bias to the control circuitry.
D
12, 13, 14, Drain: The Drain of the internal N-channel MOSFET, connect to the input power source bus
16
voltage that provides the current to the load.
GND
15
Ground: This pin is the return (ground) for the enable circuitry. Connect this pin to the
logic/system power ground.
Package Pin-Outs
7mm x 8mm 17 Pin LGA
Top view pin-out
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PI2161
Rev1.1, Page 2 of 18

Absolute Maximum Ratings
Note: Unless otherwise specified, all voltage nodes are referenced to “PG”
Drain-to-Source Voltages (VD to VSH and VSL)
60V @ 25°C
Source Current (ISH+ISL) Continuous
12A @ 25°C
Source Current (ISH+ISL) Pulsed (10μs)
100A
Source Current (ISH+ISL) Pulsed (300ns)
(1)
150A
Single Pulse Avalanche Current (T AV<11μs)
(1)
33A
Junction-to-Ambient Thermal Resistance (RθJ-A)
45°C/W (0LFM)
Junction-to-PCB Thermal Resistance (RθJ-PCB)
10°C/W
SH, SL, SP, SN to PG
SH to SL
-0.3V to 13V / 20mA
(4)
± 1.5V
VC to PG
-0.3V to 13V / 10mA
Drain (D) to PG, Drain (D) to GND
-0.3V to 60V / 10mA
-0.3V to 60V / 1mA
VO, EN
o
o
Storage Temperature
-65 C to 150 C
Operating Junction Temperature
-40°C to 140°C
Internal MOSFET Operating Junction Temperature
-40°C to 150°C
o
Lead Temperature (Soldering, 20 sec)
250 C
ESD Rating
CDM Class IV
Electrical Specifications
Unless otherwise specified: -40C < TJ < 125C, VVC-PG =10.5V, VPG=VGND=0V, CVC=0.1μF
Parameter
Symbol
Min
VVC-PG
8.5
Typ
Max
Units
Conditions
10.5
V
1.7
2.1
mA
VC = 10.5V, SP=SN=VC
VC = 8.5V, SP=SN=PG
Control Circuit Supply (VC to PG)
Operating Supply Range
Quiescent Current
Quiescent Current at Start Up
IVC
No VC limiting Resistor
IVCSU
2.0
2.5
3.0
mA
Clamp Voltage
VVC-CLM
11
11.7
12.5
V
IVC=3mA
Clamp Shunt Resistance
RSHUNT
10

Under-Voltage Rising Threshold
VVCUVLO
6.2
7.32
8.5
V
Delta IVC=10mA
VD= VVC , measure when
VD=VSH
Under-Voltage Falling Threshold
VVCUVF
6
7.00
7.9
V
VVCUV-HS
240
320
400
mV
VVD-GND
41
44
48
V
RD-VC
8
10
14
kΩ
VVD-UVLO
27
33
38
V
Under-Voltage Hysteresis
Drain Supply
Operating Supply Range
D to VC resistance
D input UVLO Rising Threshold
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PI2161
RPG=6kΩ
RPG=6kΩ, ISH=-1mA
EN =0
Rev1.1, Page 3 of 18

Electrical Specifications
Unless otherwise specified: -40C < TJ < 125C, VVC-PG =10.5V, VPG=VGND=0V, CVC=0.1μF
Parameter
Symbol
Min
Typ
Max
Units
Conditions
DIFFERENTIAL AMPLIFIER AND COMPARATORS
Common Mode Input Voltage
Differential Operating Input Voltage
VCM
(1)
VPG
VSP-SN
VVC
+0.3
250
mV
SP-SN
V
SP Input Bias Current
ISP
15
25
35
μA
SP=SN=VC
SN Input Bias Current
ISN
25
37
50
μA
SP=SN=VC
0.87
1.0
V
ISN=3mA
70
77
mV
120
200
ns
DBST Diode Forward Voltage
(SN to VC)
Low Range Overcurrent Threshold
Low Range Overcurrent Turn-off
Time
High Range Overcurrent Threshold
VDBST
VOC-THL
63
TOC-OFF
VC-SN=0V
VSP-SN = 0~200mV step to
90% of VSH max, SN=VC
VC-SN=6V
VOC-THH
133
166
200
mV
Overcurrent Hysteresis(1)
Over Current Range switch over
Threshold
Over Current Range switch over
delay(1): Low to high Threshold
Over Current Range switch over
delay: High to low threshold
Internal N-Channel MOSFET
VOC-HY
9
13
17
mV
VSOTH
0.5
0.8
1
V
VC-SN
TSOL2H
100
170
300
ns
VC-SN= -0.7V~1.7V
TSOH2L
80
125
190
ns
SN-VC= -1.7V~0.7V
Drain-to-Source Breakdown Voltage
BVDSS
60
V
ID=2mA , Tj=25°C;
Source Current Continuous
ISH+ISL
12
A
In ON state, Tj=25°C
Drain to source Off State Current
IDS-OFF
3.2
4.3
mA
Drain-to-Source On Resistance
RDSon
8.5
11
m
8
%
400
mV
153
k
5
μA
1.6
V
Current Sense Ratio (3)
KS
EN =3.3V, VD=44V, VSH=
VSL=0V
In ON state, ID=10A.
Tj=25°C
ISL/ (ISH+ISL), ID=10A(4)
Internal Schottky Diode (between PG and SH)
DClamp Forward voltage
VF
VF=10mA, Tj=25°C
Load Status Voltage (VO)
Source (SH) to VO resistance
Source to VO leakage
RSH-VO
147
150
IVOLK
Enable ( EN )
Threshold Voltage
V EN
Input bias @ 3.3V
I EN
0.4
50
μA
Note 1: These parameters are not production tested but are guaranteed by design, characterization, and correlation
with statistical process control.
Note 2: Current sourced by a pin is reported with a negative sign.
Note 3: Refer to the Current Sense section in the Functional Description
Note 4: A sense Resistor (Rs) has to be connected between SH and SL as shown in Figure 1, Rs ≤ 2Ω.
Picor Corporation • picorpower.com
PI2161
Rev1.1, Page 4 of 18

Functional Description:
The PI2161 integrated Cool-Switch product takes
advantage of two different technologies combining low
RDS(on) N-channel MOSFETs with high density control
circuitry to provide a high side fast Circuit Breaker
solution. The PI2161’s 8.5m on state resistance
MOSFET minimizes the voltage drop, at the maximum
rated current of 12A, significantly reducing power
dissipation and eliminating the need for heat sinking.
KS 
Where:
As shown in the typical application Figure 1 and the
block diagram Figure 5, the unique aspect of the load
current sensing scheme is that only a small portion of
the total MOSFET source current is routed through
the sense resistor (Rs). This allows using a much
lower power component compared to the conventional
method of sensing the total current to the load. Figure
5, Figure 6 and Figure 7 show the PI2161 block
diagram, timing diagram and state diagram
respectively.
Current Sense:
The PI2161 internal MOSFET source is split into two
portions, Source High current (SH) and Source Low
current (SL). SH conducts the majority of the current
and SL conducts a small portion of the load current.
SL current is routed through the sense Resistor (Rs)
for current sensing.
The value of the sense Resistor in the path of the
sense current, will create a voltage drop and have an
effect on the current ratio KS. The current ratio is
expressed in the following equation as a function of
RDS(on) and Rs.
Note that the MOSFET RDS(on) value is temperature
dependent and temperature will effect the current
ratio. For one RDS(on) value the current ratio is
constant with respect to the load current. Current
ratio vs. sense resistor over temperature performance
is shown in Figure 3.
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Rs :
Sense Resistor value in [mΩ]
RDS (on) :
MOSFET ON resistance value [mΩ]
KS :
Current sense ratio
I SL :
SL sense current [A]
I Load :
Load Current [A]
6.6
6.4
Typical Rds(on) at 25°C = 8.5mΩ
6.2
6.0
Current Sense Ratio (Ks) [%]
Differential Amplifier:
The PI2161 integrates a high-speed fixed offset
voltage differential amplifier to sense the difference
between the Sense Positive (SP) pin and Sense
Negative (SN) pin voltage. The amplifier output is
connected to the control logic that determines the
state of the fault latch. To avoid tripping the breaker
due to load capacitance during initial power up, a
higher threshold (VOC-THH) is used. The amplifier will
detect if the drop across the sense resistor reaches
166mV and discharge the gate of the MOSFET if
detected. Once the load voltage approaches the input
potential, the threshold (VOC-THL) is lowered to 70mV.
This allows for capacitive load charging and
continuous current sensing without the use of a sense
blanking timer.
12 * R DS ( on)
I SL

I Load 144 * R DS ( on)  ( Rs  17.5) * (11)
5.8
5.6
5.4
Jun
ctio
n
5.2
5.0
Jun
4.8
4.6
ctio
n
4.4
4.2
Te
m
pe
Tem
per
ra t
u re
4.0
atu
=2
re =
125
°C
5°C
3.8
3.6
3.4
3.2
30
40
50
60
70
80
90
100
110
120
130
140
150
Sense Resistor Value [mΩ]
Figure 3: Current ratio vs. sense resistor over
temperature
Figure 4 characterizes the trip current range between
25°C and 125°C over a range of sense resistor
values.
The equations and an example for calculating Rs
value for a trip current level and the equation for the
trip current at a given sense resistor value are
provided in the Application Information section.
Enable Input: ( EN )
This input provides control of the switch state enabling
and disabling with logic level signals. The active low
feature allows grounding or floating of the input
resulting in switch closure upon application of input
power. System control can disable the switch and
reset the over current latch by pulling this pin to a
logic high state.
Once enabled the load voltage will reach the input
voltage in typically 1 ms and the device will sense the
current continuously once the POR interval has
cleared relative to the VC to PG potential. The disable
control with this input is very fast, turning the switch
off in typically 200ns. The response to open during an
PI2161
Rev1.1, Page 5 of 18

over current event is typically 120ns and the switch
will latch off until reset by bringing this input high or
recycling of the input power.
of the MOSFET. The VC pin will be biased through
the load potential once the MOSFET is enabled.
In a high voltage application as shown in Figure 1 the
lower bias resistor RPG placed between the PG pin
and system ground is required. RPG creates an offset
voltage at the PG pin to regulate VC with respect to
PG when the MOSFET is enabled and the load
voltage reaches the input voltage.
The PI2161 has an integrated charge pump that
approximately doubles the regulated VC with respect
to PG enhancing the N-Channel MOSFET gate to
source voltage.
The internal gate driver controls the N-channel
MOSFET such that in the on state, the gate driver
applies current to the MOSFET gate driving it to bring
the load up to the input voltage and into the RDS(on)
condition.
Figure 4: Over current trip vs. sense resistor over
temperature.
When an over current condition is sensed the gate
driver pulls the gate low to PG and discharges the
MOSFET gate with 4A peak capability.
Load Status: (VO)
VC Voltage Regulator and MOSFET Drive:
The biasing scheme in the PI2161 uniquely enables
the gate control relative to the PG pin via the resistor
RPG shown in Figure 1. The VC input provides power
to the control circuitry, the charge pump and the gate
driver. An internal regulator clamps the VC voltage to
11.7V with respect to PG.
When the Gate is enabled, a 150k resistor is
connected to the MOSFET source and VO. An
external resistor between VO and ground creates a
voltage divider that scales the load voltage down to
the desired level to interface with the diagnostic circuit
to represent a logic state or analog voltage level. The
external resistor RVO can be calculated using the
following equation:
The internal regulator circuit has a comparator to
monitor VC voltage and pulls the gate low when VC to
PG is lower than the VC Under-Voltage Threshold.
RVO  150 K 
During start up or in a fault condition when the output
(Load) is shorted, the VC pin is biased through a
10KΩ (RD-VC) internal resistor connected to the drain
Where:
VO :
V SH :
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PI2161
VO
VSH  VO
Desired voltage level at VO pin
Enabled load or SH voltage
Rev1.1, Page 6 of 18

Figure 5: PI2161 block diagram
Figure 6: PI2161 timing diagram, referenced to Figure 1.
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PI2161
Rev1.1, Page 7 of 18

Figure 7: PI2161 State Diagram, referenced to Figure 1.
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PI2161
Rev1.1, Page 8 of 18

Typical Characteristics:
Figure 8: Controller bias current vs. temperature.
Figure 11: Internal MOSFET drain to source
breakdown voltage vs. temperature.
Figure 9: Low Range Overcurrent Threshold vs.
temperature.
Figure 12: Internal MOSFET on-state resistance vs.
temperature
Figure 10: Low Range Overcurrent Turn-off time vs.
temperature.
Figure 13: Internal MOSFET source to drain diode
forward voltage (pulsed ≤300µs).
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PI2161
Rev1.1, Page 9 of 18

Thermal Characteristics:
Figure 14: MOSFET Junction Temperature vs. Input
Current for a given ambient temperature
(0LFM)
Figure 16: MOSFET Junction Temperature vs. Input
Current for a given ambient temperature
(200LFM)
Figure 15: PI2161 input current de-rating based on
the MOSFET maximum TJ=150°C vs.
ambient temperature
Figure 17: PI2161 input current de-rating vs. PCB
temperature, for the MOSFET maximum TJ
at 125°C and 150°C
MOSFET
PI2161
2
Figure 18: PI2161 mounted on a 1in pad of 0.5 oz copper. Thermal Image picture, Iout=10A,
TA=25°C, Air Flow=0LFM
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PI2161
Rev1.1, Page 10 of 18

Figure 19: PI2161 response to an increase in load current
Application Information
The PI2161 Cool-Switch is a medium voltage high
side load disconnect switch.
The RPG worst case condition for power dissipation is
a function of the maximum BUS voltage and minimum
VC clamp voltage.
This section describes in detail the procedure to follow
when designing with the PI2161 load disconnect
switch.
Lower Bias Resistor selection: RPG
As described in Functional Description section, in a
floating application as shown in Figure 1 the lower
bias resistor RPG placed between the PG pin and
system ground is required. RPG creates an offset
voltage at the PG pin to regulate VC with respect to
PG when the MOSFET is enabled.
Pd RPG 
R PG
Where:
VVD UVLO min : Drain input UVLO minimum voltage, 27V
Vin max :
Vin maximum voltage, 48V
VC ClampMax : Controller maximum VC clamp voltage,
12.5V
V DBST  MAX : Maximum DBST Forward Voltage, 1.0V
The RPG resistor can be calculated using the following
expression:
R PG 
(Vin max  VC clampMIN ) 2
VC ClampMin : Controller minimum VC clamp voltage, 11V
VVD UVLO min  VC clampMAX  V DBST  MAX
I VCMAX  100 A
I VCMAX :
Controller maximum VC bias current.
100A :
2.1mA
100μA is added for a margin
Example: 41V < Vin < 48V
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PI2161
Rev1.1, Page 11 of 18

Make sure that the PI2161 to turn on below the
minimum required voltage, use 27V for the minimum
voltage to calculate RPG.
R PG 
27V  12.5V  1V
 6.136 K or 6.04KΩ
2.1mA  100 A
Pd RPG 
I TRIP 
Pd RS
(48V  11V )
 227 mW
6.04 K
The current trip point is a function of the Low Range
Overcurrent Threshold (VOC-THL), the internal MOSFET
on resistance (RDS(on)) and current sense resistor (Rs).
To insure that PI2161 will not trip within the expected
nominal operating current range, include the variation
of VOC-THL and RDS(on) in the calculation when selecting
Rs. VOC-THL is 70mV typical, 63mV minimum and
77mV maximum. The RDS(on) typical value at 25°C is
8.5mΩ and 11mΩ maximum. RDS(on) will increase with
temperature as shown in Figure 12, and can be
calculated by multiplying the RDS(on) value at 25°C by
the normalized factor in Figure 12 at the expected
operating junction temperature or use the following
equation.

RDS ( on) (TJ )  RDS ( on) (25C ) * 0.873 * e 3.75*TJ *10  0.041
2
Current sense resistor [mΩ]
I TRIP :
Current trip point [A]
VOC _ THL :
Low Range Overcurrent Threshold [mV],
This input provides control of the switch state enabling
and disabling with logic level signals.
Current Sense Resistor Selection: Rs
The Rs value can be selected from Figure 4 to set the
nominal trip current at junction temperature for internal
MOSFET of 25°C or 125°C. To set the minimum trip
current at specific junction temperature use the
following procedure.
V
 TH  MAX
Rs
Where:
Rs :
Enable Input: ( EN )
3
12 * Rs * RDS ( on)
Sense resistor Maximum power dissipation is:
2

VOC _ THL * 144 * RDS ( on)  11 * ( Rs  17.5) 
63mV minimum
VTH  MAX :
Maximum Overcurrent Threshold [mV],
77mV
Current trip calculation example:
Minimum current tripping point = 12A
Maximum MOSEFET junction temperature = 100°C.
The lowest tripping current will occur at the internal
MOSFET maximum RDS(on) and its maximum junction
temperature, and minimum Low Range Overcurrent
Threshold (VOC-THL).
The MOSET maximum RDS(on) is 11mΩ at 25°C and at
maximum junction temperature will be

3

RDS ( on) (100)  11m * 0.873 * e 3.75*100*10  0.041
R DS ( on) (100)  14.42m
Select Rs at minimum VOC-THL =63mV
Rs 
63 * 144 * 14.42  192.5
 103.32m
12 * 12 * 14.42  11 * 63
Rs maximum power dissipation:
2
Where:
Internal MOSFET Junction temperature
TJ :
R DS ( on) (TJ ) : Internal MOSFET RDS(on) at TJ in °C
R DS ( on) (25C ) : Internal MOSFET RDS(on) at TJ = 25°C
The sense resistor can be calculated from the
following equation as a function of the trip current:
Rs 
VOC _ THL * 144 * R DS ( on)  192.5
Pd RS 
This is a low power dissipation resistor and any
package size work as far by selecting the nearest
standard value. The closest resistor available value in
1% accuracy in an 0603 or 0805 package is 0.10Ω
(100mΩ).
If 0603 0.10Ω 1% resistor selected, then the minimum
trip current is:
12 * I TRIP * RDS ( on)  11 * VOC _ THL
I TRIP 
And the trip current can be calculated from the
following equation:
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VTH  MAX
0.077 2

 57.6mW
Rs
0.103
PI2161
63 * 144 * 14.42  11 * (100  17.5) 
 12.26 A
12 * 100 * 14.42
Rev1.1, Page 12 of 18

Internal N-Channel MOSFET BVDSS:
The
PI2161’s
internal
N-Channel
MOSFET
breakdown voltage (BVDSS) is rated for 60V at 25°C
and will degrade to 55.5V at -40°C, refer to Figure 11.
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 load disconnect switch applications when the load
is shorted, a large current is sourced from the input
supply through the MOSFET. Depending on the input
impedance of the system and the parasitic
inductance, the current in the MOSFET may exceed
the source pulsed current rating (150A) just before the
PI2161 MOSFET is turned off.
The peak current during an output short condition is
calculated as follows, assuming that the output has
very low impedance and it is not a limiting factor:
I PEAK 
V D * t OC OFF
L PARASITIC
Where:
I PEAK :
Peak current in PI2161 MOSFET before it is
turned off.
:
Input voltage or load voltage at D pin before
VD
input short condition did occur.
t OC  OFF : Low Range Overcurrent Turn-off Time.
LPARASITIC : Circuit parasitic inductance
The high peak current during an output short and
before the MOSFET turns off, stores energy in the
circuit parasitic inductance, and as soon as the
MOSFET turns off, the stored energy at the drain side
of the internal MOSFET will be released to produce a
voltage higher than the input voltage while the
MOSFET source is at ground. This event will create a
high voltage difference between the drain and source
of the MOSFET. The MOSFET will avalanche, but
this avalanche will not affect the MOSFET
performance because the PI2161 has a fast
response time to the input fault condition and the
stored energy will be well below the MOSFET
avalanche capability.
MOSFET avalanche energy during an output short
event is calculated as follows:
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E AS 
1.3 * BV DSS
1
2
*
* LPARASITIC * I PEAK
2 1.3 * BV DSS  VS
Where:
E AS :
Avalanche energy
BV DSS :
MOSFET maximum rated voltage (60V)
Power dissipation:
In Load Disconnect Switch applications, the MOSFET
is on in steady state operation and the power
dissipation is derived from the total source current and
the on-state resistance of the MOSFET.
The PI2161 internal MOSFET power dissipation can
be calculated with the following equation:
Pd MOSFET  Is 2  R DS ( on)
Where:
Is:
Source Current
Pd MOSFET :MOSFET power dissipation
RDS(on): MOSFET on-state resistance
Note: For the worst case condition, calculate with
maximum rated RDS(on) at the MOSFET maximum
operating junction temperature because RDS(on) is
temperature dependent. Refer to Figure 12 for
normalized RDS(on) values over temperature. The
PI2161 maximum RDS(on) at 25°C is 11mΩ and will
increase by 43% at 125°C junction temperature.
The Junction Temperature rise is a function of power
dissipation and thermal resistance.
Trise  RJA  Pd MOSFET  RJA  Is 2  R DS (on)
Where:
RJA :
Junction-to-Ambient thermal resistance
(45°C/Watt)
This calculation may require iteration to get to the final
junction temperature. Figure 14 and Figure 16 show
the PI2161 internal MOSFET final junction
temperature curves versus conducted current at
maximum RDS(on), given ambient temperatures and air
flow.
Load Status Resistor Selection: (RVO)
RVO can be calculated using the following equation:
RVO  150 K 
PI2161
VO
VSH  VO
Rev1.1, Page 13 of 18

Typical Application Example:
Load Disconnect Switch
Requirement:
Bus Voltage = 45V ±5V
Maximum Load Operating Current = 9A
Minimum Trip Current = 10A
Maximum Ambient Temperature = 60°C, no air flow
(0LFM)
The current flow parasitic inductance is 60nH.
System logic voltage is 3.3V and logic high = 2.0V
Solution:
In this application, PI2161 is used to protect the power
source from load failure, configured as shown in the
circuit schematic in Figure 21.
Power Dissipation and Junction Temperature:
First use Figure 14 (MOSFET Junction Temperature
vs. Input Current) to find the final junction temperature
for 9A load current at 60°C ambient temperature. In
Figure 14 (illustrated in Figure 20) draw a vertical line
from 9A to intersect the 60°C ambient temperature
line. At the intersection draw a horizontal line towards
the Y-axis (Junction Temperature). The Junction
Temperature at maximum load current (9A) and 60°C
ambient is 115°C.
RDS(on) is 11mΩ maximum at 25°C and will increase as
the Junction temperature increases. From Figure 12,
at 115°C RDS(on) will increase by 38%, then
RDS ( on)  11m 1.38  15.18m maximum at 115°C
Maximum power dissipation is:
RPG Selection:
For a margin purpose, select RPG to operate at input
voltage below the required operating voltage, use 27V
minimum operating voltage:
R PG 
R PG
Pd max  Iin 2  RDS ( on)  (9 A)2 15.18m  1.23W
Recalculate TJ:
 45C

TJ max  60C  
 (9 A)2 15.18m   115.3C
 W

VVD UVLO min  VC clampMAX  V DBST  MAX
I VCMAX  100 A
27V  12.5V  1V

 6.136k
2.1mA  0.1mA
The closest 1% resistor available is 6.04kΩ, RPG
power dissipation will be:
PdR PG 
(VS  max  VS  PGMin ) 2 50V  11V 2

 252mW
RPG
6.04k
The selected resistor should be capable of supporting
the total power at maximum operating temperature,
60°C. An 0805 (2012) will support the power
requirement.
VO pin:
In this application use the minimum voltage output
VSH = 40V, and for VO use the logic high voltage
(2.0V) with margin, VO = 2.1V
RVO  150 K *
2.1V
 8 .3 K 
40V  2.1V
Closest 1% resistor is 8.45kΩ to the high side
Calculate VO at VSH = 40V and RVO=8.45kΩ
Figure 20: Example 1 final MOSFET junction
temperature at 9A/60°C TA
Select Rs:
The minimum trip current will occur at maximum
MOSFET junction temperature and VOC-THL = 63mV:
RVO
150 K  RVO
8.45 K
VO  40V *
 2.133
150 K  8.45 K
VO  VSH *
Picor Corporation • picorpower.com
PI2161
Rev1.1, Page 14 of 18

MOSFET Junction Temperature for 10A at 60°C can
be estimated using the graph in Figure 14 as
illustrated in Figure 20. Draw a vertical line from 10A
to intersect the 60°C ambient temperature line. At the
intersection draw a horizontal line towards the Y-axis
(Junction Temperature). The Junction Temperature at
maximum load current (10A) and 60°C ambient is
133°C.

3
The minimum trip current is:
I TRIP 
I TRIP 
VOC _ THL * 144 * RDS ( on)  11 * ( Rs  17.5) 
12 * Rs * RDS ( on)
63 * 144 * 16.26  11 * (130  17.5) 
 9.85 A
12 * 130 * 16.26

RDS ( on) (TJ )  RDS ( on) (25C ) * 0.873 * e 3.75*TJ *10  0.041

3

RDS (on) (133)  11m * 0.873 * e 3.75*133*10  0.041
R DS ( on) (133)  16.26m
Rs 
Rs 
VOC _ THL * 144 * R DS ( on)  192.5
12 * I TRIP * RDS ( on)  11 * VOC _ THL
63 * 144 * 16.26  192.5
 126.9m
12 * 10 * 16.26  11 * 63
The closest 1% resistor available off-the-shelf is
130mΩ.
Figure 21: PI2161 configured for 10A minimum trip
current
Layout Recommendation:
Use the following general guidelines when designing
printed circuit boards. An example of the typical land
pattern for the PI2161 is shown in Figure 22.

Use a solid ground (return) plane to reduce circuit
parasitic.

Connect Rs terminal at SN pin side and all S pads
together with a wide trace to reduce trace
parasitics and to accommodate the high current
output, and also connect all D pads together with
a wide trace to accommodate the high current
input.

Kelvin connect SP pin and SN pin to Rs terminals
to the S pins.

Connect SL pins together with a wide trace
connect them to Rs.

Place CVC very close to PI2161 to have very short
traces to PI2161 pins without any PCB via in
between.

Use 1oz of copper or thicker if possible to reduce
trace resistance and reduce power dissipation.
Picor Corporation • picorpower.com
Figure 22: PI2161 layout recommendation
PI2161
Rev1.1, Page 15 of 18

Package Drawings
All dimensions are in mm
Ordering Information
Part Number
Package
PI2161-01-LGIZ
7mm x 8mm 17-pin LGA
Picor Corporation • picorpower.com
Transport Media
T&R
PI2161
Rev1.1, Page 16 of 18

Footprint Recommendation:
Picor Corporation • picorpower.com
PI2161
Rev1.1, Page 17 of 18

Warranty
Vicor products are guaranteed for two years from date of shipment against defects in material or workmanship when
in normal use and service. This warranty does not extend to products subjected to misuse, accident, or improper
application or maintenance. Vicor shall not be liable for collateral or consequential damage. This warranty is
extended to the original purchaser only.
EXCEPT FOR THE FOREGOING EXPRESS WARRANTY, VICOR MAKES NO WARRANTY, EXPRESS OR
LIMITED, INCLUDING, BUT NOT LIMITED TO, THE WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
Vicor will repair or replace defective products in accordance with its own best judgment. For service under this
warranty, the buyer must contact Vicor to obtain a Return Material Authorization (RMA) number and shipping
instructions. Products returned without prior authorization will be returned to the buyer. The buyer will pay all charges
incurred in returning the product to the factory. Vicor will pay all reshipment charges if the product was defective
within the terms of this warranty.
Information published by Vicor has been carefully checked and is believed to be accurate; however, no responsibility
is assumed for inaccuracies. Vicor reserves the right to make changes to any products without further notice to
improve reliability, function, or design. Vicor does not assume any liability arising out of the application or use of any
product or circuit; neither does it convey any license under its patent rights nor the rights of others. Vicor general
policy does not recommend the use of its components in life support applications wherein a failure or malfunction
may directly threaten life or injury. Per Vicor Terms and Conditions of Sale, the user of Vicor components in life
support applications assumes all risks of such use and indemnifies Vicor against all damages.
Vicor’s comprehensive line of power solutions includes high density AC-DC and DC-DC
modules and accessory components, fully configurable AC-DC and DC-DC power
supplies, and complete custom power systems.
Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor
for its use. Vicor components are not designed to be used in applications, such as life support systems, wherein a
failure or malfunction could result in injury or death. All sales are subject to Vicor’s Terms and Conditions of Sale,
which are available upon request.
Specifications are subject to change without notice.
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25 Frontage Road
Andover, MA 01810
USA
Picor Corporation
51 Industrial Drive
North Smithfield, RI 02896
USA
Customer Service: [email protected]
Technical Support: [email protected]
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Picor Corporation • picorpower.com
PI2161
Rev1.1, Page 18 of 18
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