Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 1 of 16
PI2061
Cool-Switch® Series
High Side High Voltage Load Disconnect Switch Controller IC
Description
The PI2061 is a high-speed electronic circuit breaker
controller IC designed for use with N-channel MOSFETs in
high side load disconnect switch solutions for medium
voltage applications. The PI2061 Cool-Switch® controller
enables an extremely low power loss solution with fast
dynamic response to an over current fault or EN Low
conditions.
Once enabled, the PI2061 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 low will reset the over current latch allowing retry. To
avoid false tripping by the in-rush current, the over
current level is approximately doubled during start up,
until SN approaches about 0.8V below VC. The PI2061
has an internal charge pump to drive the gate of a high
side N-Channel MOSFET above the VC input. There is an
internal shunt regulator that regulates the VC input with
respect to the SGND pin for applications higher than 11
volts.
Features
Programmable latching over-current detection
Fast 120ns disconnect response to a load short
Fast disable via EN pin, typically 200ns.
4A gate discharge current
Internal charge pump
Fault status indication
Applications
Transient
N+1 Redundant Power Systems
Servers & High End Computing
High Side Circuit Breaker and Load Disconnect
Package Information
The PI2061 is offered in the following package:
10 Lead 3mm x 3mm DFN package
Table of Contents:
Pin Description 2
Electrical Specifications 3
Functional Description 5
Block Diagram 6
State Diagram 7
Typical Characteristics Plots 8
Application Information 9
12V Typical Application Example 12
48V Typical application Example 13
Layout Recommendation 14
Package Drawings 15
Ordering Information 15
Typical Application:
Figure 1: PI2061 in High Side Disconnect switch application
Figure 2: PI2061 response time to output short fault condition
Vin
PGND
SN
SGND
PI2061
1
7
0.1µF 4
9
FT
EN
5
RTN
VC
3
LOAD
RPG
FT
VC
Vout
Iout
D1
RVC
GATE
6
2
SP
RS
D2
Event: Output Short
Vin
Vout
120ns
Over Current detection
MOSFET Turn Off Time
0A
0V
Normal operation
Output Current
Current Trip Level
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 2 of 16
Pin Description
Pin Name
Pin
Number
Description
PGND
1
Gate Driver Switch Return: This pin is the high current return path for the gate driver turn off switch.
Connect this pin to the low side of VC bypass capacitor and SGND.
GATE
2
Gate Drive Output: This pin drives the gate of the external N-channel MOSFET. Under normal
operating conditions, the GATE pin pulls high to approximately 2*VC with respect to SGND pin. The
controller turns the GATE off during an over-current fault that is above the overcurrent voltage
threshold (166mV during power up and 70mV in steady state).
VC
3
Controller Input Supply: This pin is the supply pin for the control circuitry and gate driver. Connect
a 0.
with respect to SGND by an internal shunt regulator. Connect a bias resistor (RVC) between the VC
pin and the supply input as shown in Figure 1.
SGND
4
VC Return: This pin is the return (ground) for the control circuitry. Connect this pin to the low side of
the VC bypass capacitor and high side of the RPG resistor as shown in Figure 1.
EN
5
Enable: Pull this pin low with 8µA or more to disable the gate driver and reset the latch. Tie this pin
to VC if the Enable/disable feature is not used.
SP
6
Positive Sense Input & Clamp: Connect SP pin to the positive side of the sense resistor. The
magnitude of the voltage difference between SP and SN provides an indication of the current
through the sense resistor.
SN
7
Negative Sense Input & Clamp: Connect SN pin to the negative side of the sense resistor. The
magnitude of the voltage difference between SP and SN provides an indication of the load current
through the sense resistor.
NC
8, 10
No Connect: Leave pins unconnected
FT
9
Fault Status Output: This open collector pin transitions to high resistance to indicate a fault. When
the controller input voltage is in under voltage, VC - SGND < 7V this pin is high resistance as well.
When the part is in a normal operating condition and gate driver is enabled this pin is low resistance.
Package Pin-Outs
10 Lead DFN (3mm x 3mm)
Top view
1
2
3
4
5
10
9
8
7
6
GATE
VC
NCPGND
EN
SGND SN
NC
FT
SP
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 3 of 16
Absolute Maximum Ratings
Note: All voltage nodes are referenced to SGND
VC
-0.3V to 17.3V / 40mA
SP, SN, FT, EN
-0.3V to 17.3V / 10mA
GATE
-0.3V to 24V / 5A peak
PGND
-0.3V to 3V / 5A peak
SGND
40mA
Storage Temperature
-65oC to 150oC
Operating Junction Temperature
-40oC to 140°C
Soldering Temperature for 20 seconds
260°C
ESD Rating
2kV HBM
Electrical Specifications
Unless otherwise specified: -40C < TJ < 125C, VC=EN=10.5V, CVc =0.1uF, CGATE_PGND =1nF, SGND=PGND
Parameter
Symbol
Min
Typ
Max
Units
Conditions
VC Supply
Operating Supply Range
VVC-SGND
8.5
10.5
V
No VC limiting Resistor
Quiescent Current
IVC
1.7
2.1
mA
VC = 10.5V, SP=SN=VC
Quiescent Current Start Up
IVCSU
2.0
2.5
3.0
mA
VC = 8.5V, SP=SN=SGND
VC Clamp Voltage
VVC-CLM
11
11.7
12.5
V
IVC=3mA
VC Clamp Series Resistance
RVC
10
Delta IVC=10mA
VC Under-Voltage Rising Threshold
VVCUVR
6.2
7.32
8.5
V
VC Under-Voltage Falling Threshold
VVCUVF
6
7.00
7.9
V
VC Under-Voltage Hysteresis
VVCUV-HS
240
320
400
mV
DIFFERENTIAL AMPLIFIER AND COMPARATORS
Common Mode Input Voltage
VCM
VSGND
VVC +0.3
V
Differential Operating Input Voltage(1)
VSP-SN
250
mV
SP-SN
SP Input Bias Current
ISP
15
25
35
SP=SN=VC
SN Input Bias Current
ISN
25
37
50
SP=SN=VC
DBST Forward Voltage
VDBST
0.87
1.0
V
ISN=3mA
Low Range Overcurrent Threshold
VOC-THL
63
70
77
mV
VC-SN=0V
Low Range Overcurrent Turn-off Time
TOC-OFF
120
200
ns
VSP-SN = 0V to 200mV step to 90%
of VG max, SN=VC
High Range Overcurrent Threshold
VOC-THH
133
166
200
mV
VC-SN=6V
Overcurrent Hysteresis(1)
VOC-HY
9
13
17
mV
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 4 of 16
Electrical Specifications
Unless otherwise specified: -40C < TJ < 125C, VC=EN=10.5V, CVc =0.1uF, CGATE_PGND =1nF, SGND=PGND
Parameter
Symbol
Min
Typ
Max
Units
Conditions
DIFFERENTIAL AMPLIFIER AND COMPARATORS (continued)
Over Current Range switch over
Threshold
VSOTH
0.5
0.8
1
V
VC-SN
Over Current Range switch over delay(1):
Low to high threshold
TSOL2H
100
170
300
ns
VC-SN= -0.7V~1.7V
Over Current Range switch over delay(1):
High to low threshold
TSOH2L
80
125
190
ns
SN-VC= -1.7V~0.7V
GATE DRIVER
Gate Source Current
IG-SC
-15
-10
µA
VG=VG-Hi-1, IVC=3mA
Pull Down Peak Current to PGND(1)
IG-PD
1.5
4.0
A
Pull-down Gate Resistance to PGND(1)
RG-PD
0.3
VG = 1.5V @ 25C
AC Gate Pull-down Voltage to PGND(1)
VG-PGND
0.2
V
DC Gate Pull-down Voltage
VG-SGND
0.8
1.2
V
IG=100mA, in OC Fault
Gate Drive Voltage to VC
VG-Hi
7.0
8.0
11
V
IGVC=3mA
8.0
9.0
11
V
IGVC=3mA
Gate Fall Time
tG-F
10
25
ns
90% to 10% of VG max.
Gate Voltage @ VC=4.5V
VG-UVLO
0.7
1
V
IG =10µA, SP= SN=open
Enable (EN)
EN Threshold Voltage to VC pin
VVC_EN
0.70
1.35
1.80
V
Disable pull down current
Idis
8
15
22
µA
Fault Status: FT
FT Output Low Voltage
VFT
0.2
0.5
V
IFT=200µA, VC>8.5V
FT Output High Leakage Current
IFT
10
VFT=14V
FT Delay time
TFT-DLY
2.5
5.5
12
µs
VSP-SN = 0~200mV step to 10% of
VFT max, SN=VC
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.
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 5 of 16
Functional Description:
The PI2061 Cool-Switch is designed to drive an N-channel
MOSFET in a high side Circuit Breaker application. As
shown in Figure 1, the load current is sensed through the
sense resistor (Rs). At power up the controller has a
higher threshold voltage compared to steady state
operation to allow capacitive load charging without
nuisance tripping of the breaker.
Differential Amplifier:
The PI2061 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 with high accuracy. 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 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 is
lowered to 70mV. This allows for capacitive load
charging and continuous current sensing without the use
of a fixed sense blanking timer where excessive currents
may develop glitching the input bus prior to breaking.
VC Voltage Regulator and MOSFET Drive:
The biasing scheme in the PI2061 uniquely enables the
gate control relative to SGND and PGND pins 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 SGND.
The VC pin is connected through an external resistor to
the input power source and drain of the MOSFET. VC
switches over to the load potential once the gate drive is
enabled and over current condition is not present.
The internal regulator circuit has a comparator to
monitor VC voltage and pulls the gate low when VC to
SGND is lower than the VC Under-Voltage Threshold. As
shown in Figure 1 the lower bias resistor, RPG is placed
between the SGND connection and the system ground.
Gate Driver:
The PI2061 has an integrated charge pump that
approximately doubles the regulated VC with respect to
SGND 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.
When an over current condition is sensed the gate driver
pulls the gate low to PGND and discharges the MOSFET
gate with 4A peak capability. A Schottky diode (D1 in
Figure 1) from PGND to the MOSFET source is required to
direct the Gate high discharge current into the Source.
The PI2061 applies high gate discharge current for fast
MOSFET turn off when a fault condition occurs to
prevent system disruption. Fast MOSFET turn off may
produce high voltage ringing due to parasitic inductance.
To prevent negative peaks at SN from injecting substrate
current, Schottky diode D2 (from SGND/PGND to SN pin
as shown in Figure 1) is required.
Enable Input: (EN)
This input provides control of the switch state enabling
and disabling with low current level signals. The active
high feature allows pulling/sinking a low current from
this input to disable the breaker. System control can
disable the switch and reset the over current latch by
pulling this pin to a logic low state.
Once enabled, the Gate pin will charge the MOSFET gate
to turn the load on. The load voltage will rise, reach the
input voltage and the device will sense the current
continuously once the POR interval has cleared relative
to the VC to SGND potential. The disable control with this
input is very fast, turning the switch off in typically
200ns. The response to open during an over current
event is typically 120ns and the switch will latch off until
reset by bringing this input low or recycling of the input
power.
Fault Status: (FT)
This open collector pin transitions to high resistance after
n over-current
fault or disable signal occurs. When the controller input
voltage is in under voltage, (VC - SGND < 7V) this pin is
high resistance as well. When the part is in a normal
operating condition and gate driver is enabled this pin is
low resistance. In high voltage applications this output
must be translated to the system return with external
circuitry. Leave this pin open if unused.
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 6 of 16
Figure 3: PI2061 Block Diagram
Figure 4: PI2061 Timing Diagram, referenced to Figure 1.
SGND
Gate
Driver
Gate
ENABLE
Q
6
SP
7
SN Set
EN
Differential
Amplifier
Reset
VC
7.15V +
-
Fault Latch
3
11.7V
+
-
+
-
2X
Charge
Pump
4
DISABLE
PGND
1
+
-
VSOTH
-
+
-+
166mV
70mV
-
+
NC
5
GATE
2
FT
9
DIS
Delay
POR
DBST
8 10
NC
Gate
VC
Iout
EN
Vin
Initial Power-up Disabled Over Current
Latched
Reset
Vout
Over Current Threshold
FT
Latched
VOC-THL
VOC-THH
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 7 of 16
.
Figure 5: PI2061 State Diagram
Reset Latch
Enable Gate
VOC-THH
FT = Low
Gate Low
FT : High
Gate Low
FT : High
VVC-SGND >7.32V
VVC-SGND< 7.0V
VVC-SGND< 7.0V
VVC-SGND < 7.32V
SP-SN < 70mV
FT = Low
VOC-THL
Hold Gate High
SP-SN > 70mV
VVC-SGND< 7.0V
Pull Gate Low
& Latch
FT = High
SP-SN < 166mV
SP-SN > 166mV
VVC-SGND< 7.0V
VC-SN < 0.8V
VC-SN > 0.8V
EN=Low
EN=High
EN=High
EN=Low
EN=Low
EN=Low
EN=Low
EN=Low
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 8 of 16
Typical Characteristics:
Figure 6: Controller quiescent current vs. temperature.
Figure 7: VC Under-Voltage Rising threshold vs.
temperature
Figure 8: Gate source current vs. temperature
Figure 9: Gate drive voltage to VC vs. temperature.
Figure 10: Low Range Overcurrent Turn-off time vs.
temperature.
Figure 11: Low Range Overcurrent Threshold vs.
temperature.
1.58
1.60
1.62
1.64
1.66
1.68
1.70
1.72
-50 -25 025 50 75 100 125 150
VC Quiescent Current [mA]
Junction Temperature [°C]
7.24
7.26
7.28
7.30
7.32
7.34
7.36
-50 -25 025 50 75 100 125 150
VC UVLO Rising Threshold [V]
Junction Temperature [°C]
-17
-16
-15
-14
-13
-12
-11
-50 -25 025 50 75 100 125 150
Gate Source Current [A]
Junction Temperature [°C]
8.7
8.8
8.9
9.0
9.1
9.2
9.3
-50 -25 025 50 75 100 125 150
Gate Drive Voltage to VC [V]
Junction Temperature [°C]
118
120
122
124
126
128
130
132
-50 -25 025 50 75 100 125 150
Low Range OCTurn-off time [ns]
Junction Temperature [°C]
68.0
68.5
69.0
69.5
70.0
70.5
71.0
-50 -25 025 50 75 100 125 150
Low Overcurrent Threshold [mV]
Junction Temperature [°C]
VVC-SGND=10.5V
IG=2μA
IVC=3mA
VVC-SGND=10.5V
VG=VG-Hi-1V
IVC=3mA
VVC-SGND=10.5V
VSP-SN =0V to 200mV step
VC=SN
VVC-SGND=10.5V
VC=SN
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 9 of 16
Application Information
The PI2061 Cool-Switch is a wide input voltage high side
load disconnect switch.
This section describes in detail the procedure to follow
when designing with the PI2061 load disconnect switch.
Biasing sequence Functionality
When Vin is applied and the load is at zero volts, the VC
capacitor will charge via current flowing through RVC, D1,
load resistance and RPG. If the load resistance is much
lower than RPG, most of the charge and bias current flows
through the load.
As VC to SGND voltage rises above the Under-Voltage
Rising Threshold (VVCUVR) while the EN pin is High, the
controller will charge the MOSFET gate and monitor the
voltage across the sense resistor (VSP-SN). As the MOSFET
turns on, the load voltage (Vout) will rise until the MOSFET
is in RDS(on) and Vload=Vin. If the voltage across the sense
resistor () is higher than the High Range Overcurrent
Threshold (VOC-THH166mV) while the load rises, the gate
will be discharged to PGND and latch off; otherwise Vout
will keep rising, D1 becomes reverse biased and the
controller bias current returns to ground through RPG.
When Vout reaches the Over Current Range switch over
threshold, the over current threshold switches to the Low
Range Over Current threshold (VOC-THL 70mV). VC will be
biased from Vout through the SN pin when Vout is a diode
drop (DBST) above VC as the load reaches Vin.
Upper and lower bias resistors should be selected to keep
PI2061 bias voltage in regulation.
Upper Side Bias Resistor selection: RVC
RVC is placed between Vin and VC to limit the current into
the clamp under a shorted load condition. This will allow
VC to regulate with respect to SGND/PDND node when the
MOSFET is in off condition and SGND/PGND node is pulled
low via D1, Rs and low load resistance.
The RVC resistor can be calculated using the following
expression:
And RVC maximum power dissipation is:
Where:
: Vin minimum voltage (Vin to Rtn)
: Vin maximum voltage (Vin to Rtn)
: VC maximum clamp voltage, 12.5V
: VC minimum clamp voltage, 11V
: VC maximum quiescent current at startup,
use 3.0mA
: D1 voltage drop, use 0.3V
: 0.1mA is added for margin
Lower Side Bias Resistor selection: RPG
RPG is placed between SGND/PGND and return to limit the
clamp current and allow VC regulation when the MOSFET
is in the on condition.
The RPG resistor can be calculated using the following
expression:
And RVC maximum power dissipation is:
Where:
: Boot Strap diode minimum forward
voltage, use 0.8V
: Boot Strap diode minimum forward
voltage, use 1.0V
: VC maximum quiescent current, use
2.1mA
RVC and RPG calculation example
Vin (minimum) = 40V and Vin (maximum) = 50V
Note that in the case of a light load while the PI2061 is
disabled, a voltage will appear at Vout due to the
resistance between the VC pin and the SP and SN pins.
The approximate value will be:
Where:
: Output load resistance when the load is inactive
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 10 of 16
Schottky Diodes Selection: D1 and D2
Diode D1 (See Figure 1 & Figure 14.) must be a low reverse
leakage Schottky diode capable of supporting 4A of peak
gate discharge current for 10ns. Diode D2 must be a low
reverse leakage Schottky diode capable of supporting 1A
peak. Both diodes will have a reverse voltage of 13V
during normal operation.
Recommended diode for D1 and D2: PMEG4005EJ from
NXP
Sense Resistor Selection: Rs
In typical load switch application the sense resistor is
based on minimum trip current to allow maximum normal
load current without interruption. Calculate Rs value at
minimum Low Range Overcurrent Threshold voltage
(VOC-THL):
Where:
: Minimum Low Range Overcurrent
Threshold voltage, 63mV
: Required minimum trip current
Enable Input Circuit: EN
EN pin can be tied directly to VC OR LEFT FLOATING if
PI2061 should be enabled when the power is applied. If
the user wants to control the device enable function, then
EN pin can be pulled low with a resistor and signal FET,
signal transistor or open collector logic as shown in Figure
12. Note that the enable control signal phase must be
inverted.
Use an enable resistor (REN
with voltage rating that meets maximum input
voltage.
Figure 12: Enable circuit
Fault Indication: FT
FT is an open collector output and its return is referenced
to SGND. When the SGND pin is floating on a bias resistor
(RPG) or in a constant current circuit, a level shift circuit can
be added to create an output referenced to the system
ground. See Figure 13.
Figure 13: FT level shift circuit
Alternative Bias Circuit: Constant current circuit for high
voltage application.
In a wide operating input voltage range the size of RVC and
RPG may be become large to support power dissipation. A
simple constant current circuit, shown in Figure 14 can be
used instead of RVC and RPG to allow the circuit to operate
between 18V and 80V (100V/100ms transient) with low
power dissipation components. Please refer to Picor
application notes for more details on how to design a
floating bias with the constant current circuit.
Figure 14: Constant current bias circuit
Vin
PGND
SNGATE
SGND
PI2061
6
1
72
SP
4
EN
5
RTN
VC
3
RPG
RS
VC
Vout
D2
RVC
REN
EN QEN
D1
100k
100k
100k
FT
Q2
Vin
PGND
SNGATE
SGND
PI2061
1
72
4
EN
5
RTN
VC
3
RPG
RS
VC
Vout
RVC
FT
VC
Q1
6
SP
15k
D2 D1
Vin
PGND
SNGATE
SGND
PI2061
6
1
72
SP
4
EN
5
VC
3
RS
Vout
D1
6.8V
50k
1k
Q1
2.6k
50k
Q2
6.8V
RTN
1µF
FJV1845
FJV1845
2k
PMEG4005EJ
IRF7853PbF
M1
10m
CVC
PMEG4005EJ
D2
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 11 of 16
N-Channel MOSFET Selection:
Several factors affect MOSFET selection including cost and
following ratings; on-state resistance (RDS(on)), DC current,
short pulse current, avalanche, power dissipation, thermal
conductivity, drain-to-source breakdown voltage (BVDSS),
gate-to-source voltage (VGS), and gate threshold voltage
(VGS (TH)).
The first step is to select a suitable MOSFET based on the
BVDSS requirement for the application. The BVDSS voltage
rating should be higher than the applied Vin voltage plus
expected transient voltages. Stray parasitic inductance in
the circuit can also contribute to significant transient
voltage condition, particularly during MOSFET turn-off
after an over current fault has been detected.
In a disconnect switch application when the output is
shorted, a large current is sourced from the power source
through the MOSFET. Depending on the input impedance
of the system, the current may get very high before the
MOSFET is turned off. Make sure that the MOSFET pulse
current capability can withstand the peak current. Also,
such high current conditions will store energy even in a
small parasitic inductance. The PI2061 has a very fast
response time to terminate a fault condition achieving
120ns typical and 200ns maximum. This fast response time
will minimize the peak current to keep stored energy and
MOSFET avalanche energy very low to avoid damage
(electrical stress) to the MOSFET.
Peak current during output short is calculated as follows,
assuming that the input power source has very low
impedance and it is not a limiting factor:
Where:
: Peak current in the MOSFET right before
it is turned off.
: Input voltage at MOSFET drain before
output short condition occurred.
: Over current turn-off time. This will
include PI2061 delay and the MOSFET
turn off time.
: Circuit parasitic inductance
The MOSFET avalanche energy during an input short is
calculated as follows:
Where:
: Avalanche energy
: MOSFET breakdown voltage
MOSFET RDS(on) and maximum steady state power
dissipation are closely related. Generally the lower the
MOSFET RDS(on), the higher the current capability and the
lower the resultant power dissipation for a given current.
This leads to reduced thermal management overhead, but
will ultimately be higher cost compared to higher RDS(on)
parts. It is important to understand the primary design goal
objectives for the application in order to effectively trade
off the performance of one MOSFET versus another.
Power dissipation in load switch circuits is derived from the
total drain current and the on-state resistance of the
selected MOSFET.
MOSFET power dissipation:
Where :
: MOSFET Drain Current
: MOSFET on-state resistance
Note:
In the calculation use RDS(on) at maximum MOSFET
temperature because RDS(on) is temperature dependent.
Refer to the normalized RDS(on) curves in the MOSFET
manufacturer’s datasheet. Some MOSFET RDS(on) values
may increase by 50% at 125°C compared to values at 25°C.
The Junction Temperature rise is a function of power
dissipation and thermal resistance.
Where:
: MOSFET Junction-to-Ambient thermal
resistance
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 12 of 16
Typical Application Example 1:
12V Load Switch
Requirement:
Input Bus Voltage = 12V (±10% , 10.8V to 13.2V)
Maximum Load Current = 10A
Minimum Trip current = 12A
Maximum Ambient Temperature = 75°C
Solution:
PI2061 with a suitable external MOSFET should be used,
configured as shown in the circuit schematic in .
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 the Si4630DY from Siliconix.
From Si4630DY datasheet:
N-Channel MOSFET
VDS= 25V
ID = 32A continuous drain current
ID(Pulse) = 70A Pulsed drain current
VGS(MAX)=±16V
R= 80°C/W under Steady State condition
RDS(on)=2.
ID=20A, VGS=10V, TJ=25°C
Select Sense Resistor:
Rs power dissipation at maximum operating current
Maximum trip current
Power dissipation:
RDS(on) is 2.7 10 VGS 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 115°C (75°C
+ 40°C) RDS(on) will increase by 37%.
maximum at 115°C
Maximum Junction temperature
VC Bias: Vin maximum input is 13.2V, this is higher than
the 11V VC minimum Clamp Voltage (VVC-SGND) minimum,
but the minimum input voltage is greater than VVC-SGND
minimum. Use 3 VC and RPG to
minimize regulator clamp current.
Power dissipation of RVC and RPG:
Both resistors have very low power dissipation, less than
50mW. Any package size resistor, 0201 (0603 metric) or
larger, can be used.
EN:
Tie EN pin to VC since Enable function is always on.
FT:
Fault function is not required, leave fault pin unconnected.
Figure 15: PI2061 in 12V Bus high side load switch
application.
Vin
PGND
SN
GATE
SGND
PI2061
6
1
72
0.1µF
SP
4
EN
5
RTN
VC
3
300
5m
VC
Vout
300
Si4630DY
RS
M1
D1
PMEG4005EJ
D2
PMEG4005EJ
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 13 of 16
Typical application Example 2:
Requirement:
+48V Load Switch with Enable Function
Bus Voltage = +48V (+36V to +55V)
Maximum Load Current = 5A
Minimum Trip current = 6A
Maximum Ambient Temperature = 60°C
Solution:
PI2061 with a suitable MOSFET should be used and
configured as shown in Figure 16.
Select a suitable N-Channel MOSFET: Select a 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
R= 50°C/W on 1in2
R for continuous operation not provided
RDS(on)GS=10V, TJ=25°C
RDS(on)GS=10V, TJ=25°C
Select Sense Resistor:
Rs power dissipation at maximum operating current
Maximum trip current
Power dissipation:
RDS(on) VGS 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%.
at maximum at 80°C
Maximum Junction temperature
Recalculate maximum RDS(on) at 95°C.
At 95°C RDS(on) will increase by 50%:
at maximum at 95°C
Maximum Junction temperature after 10s
For continuous operation refer the MOSFET datasheet for
R under continuous operation and use in place of
50°C/W.
VC Bias Resistors:
Select 10
Power dissipation of RVC and RPG:
Recommended Schottky: PMEG4005EJ from NXP or
equivalent
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 14 of 16
Enable Input Circuit: EN
Pull EN pin to ground (return) to disable. This can be
accomplished with a signal transistor (Q1) in open
collector configuration and a pull-up resistor REN.
A 5% 36can be used to pull down on EN pin.
Note that the control signal phase is inverted.
Figure 16: PI2061 in high side +48V application, VC is
biased through a bias resistor
Layout Recommendation:
Use the following general guidelines when designing
printed circuit boards. An example of the typical land
pattern for the PI2061 is shown in Figure 17.
Use a solid ground (return) plane to reduce circuit
parasitics.
Connect Rs terminal at SP pin side, D1 cathode and all
MOSFET source pins together with a wide trace to
reduce trace parasitics and to accommodate the high
current output. Connect Rs terminal at SN pin side to
the load with a wide trace. Also connect all MOSFET
drain pins together with a wide trace to accommodate
the high current input
Kelvin connect SP pin and SN pin to Rs terminals.
The VC bypass capacitor should be located as close as
possible to the VC and SGND pins. Place the PI2061
and VC bypass capacitor on the same layer of the
board. The VC pin and CVC PCB trace should not
contain any vias.
Dedicate a small copper area on lower layer
underneath the controller for PGND and SGND to
make a single point connection and simplify layout
inter connect. Make sure that Vin to Vout current
return path is solid underneath the MOSFET (M1) and
the sense resistor (R1).
Make sure D1 and D2 connecting traces are very short
to reduce parasitic inductance that might produce
voltage drop due MOSFET fast turn off.
Use 1oz of copper or thicker if possible to reduce trace
resistance and power dissipation.
Figure 17: PI2061 layout recommendation
Vin
PGND
SN
GATE
SGND
PI2061
6
1
72
0.1µF
SP
4
EN
5
RTN
VC
3
10K
10m
VC
Vout
D1
7.5K
IRF7853PbF
RS
M1
REN
EN
360K
FT
PMEG4005EJ
D2
PMEG4005EJ
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 15 of 16
Package Drawings:
10 Lead DFN
Ordering Information
Part Number
Package
Transport Media
PI2061-00-QEIG
3mm x 3mm 10 Lead DFN
T&R
Picor Corporation • picorpower.com
PI2061
Rev 1.4
Page 16 of 16
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
malfunc
upon request.
Specifications are subject to change without notice.
Vicor Corporation Picor Corporation
25 Frontage Road 51 Industrial Drive
Andover, MA 01810 North Smithfield, RI 02896
USA USA
Customer Service: custserv@vicorpower.com
Technical Support: apps@vicorpower.com
Tel: 800-735-6200
Fax: 978-475-6715
