PI2122-00-LGIZ [VICOR]
12Amp Active ORing Solution With Load Disconnect; 12Amp有源ORing解决方案连负载切断
| 型号： | PI2122-00-LGIZ |
| 厂家： | 
VICOR CORPORATION |
| 描述： | 12Amp Active ORing Solution With Load Disconnect |
| 文件： | 总19页 (文件大小：922K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PI2122
Cool-ORing Series
12Amp Active ORing Solution With Load Disconnect
Description
Features
The Cool-ORing PI2122 is a complete full-function
Active ORing solution with a high-speed ORing
•
•
•
•
Integrated High Performance 12A, 6mΩ back-to-
back MOSFET
MOSFET controller and
a very low on-state
Very-small, high density fully-optimized solution
providing simple PCB layout.
Fast Dynamic Response, with 140ns reverse &
170ns forward over-current turn-off delay time
Accurate sensing capability to indicate system
fault conditions
Programmable under & over-voltage functions
Over temperature shutdown
Programmable over-current off time
Programmable short circuit load detection
Active low fault flag output
resistance Dual MOSFETs designed for use in
redundant power system architectures. The PI2122
Cool-ORing solution is offered in an extremely small,
thermally enhanced LGA package and can be used
in low voltage (≤ 5Vbus) high side Active ORing
applications. The PI2122 enables extremely low
power loss with fast dynamic response to fault
conditions, critical for high availability systems. The
PI2122 provide true bi-directional switch capabilities
to protect against both power source and load fault
conditions.
•
•
•
•
•
A load short circuit detection feature allows user
definition of a short condition enabling minimum duty
cycle into a short. The PI2122 has the added benefit
of being able to protect against output load fault
conditions that may induce excessive forward
current and device over-temperature by turning off
the back-to-back MOSFETs with an auto-retry
programmable off-time. The back-to-back MOSFETs
drain-to-drain voltage is monitored to detect normal
forward, excessive forward, light load and reverse
current flow. The status is reported via an active low
fault flag output. A temperature sensing function
turns off the MOSFETs and indicates a fault if the
controller junction temperature exceeds 145°C.
Applications
•
•
•
•
•
N+1 Redundant Power Systems
Servers & High End Computing
High-side Active ORing
High current Active ORing ( ≤ 5Vbus)
MicroTCA
Package
•
5mm x 7mm 17-pin Thermally Enhanced LGA
Package
Typical Application:
Figure 1: PI2122 input current de-rating based on
Figure 1: PI2122 High Side Active ORing
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 1 of 19
Pin Description
Pin Number Pin Name
Description
1, 15, 16, 17,
D2
Drain 2- Drain 2 of the internal Dual N-channel MOSFETs, connect to the output
load.
22,23, 24, 25
2, 3, 4, 5,
18,19,20, 21
Drain 1- Drain 1 of the internal Dual N-channel MOSFETs, connect to the input
voltage.
D1
Positive Sense Input & Clamp: Connect SP pin to the D1 pin. The polarity and
magnitude of the voltage difference between SP and SN provides an indication of
current flow direction through the MOSFETs.
6
SP
Fault State Output: This open collector output pulls low after the 40usec fault timer
delay when a fault condition occurs. Fault logic inputs are VC Under-Voltage, input
Under-Voltage, input Over-Voltage, Forward Over-Current, Reverse Current, Low
Forward Current (or shorted switches) and Over-Temperature. Leave this pin open
if unused.
7
FT
Short Circuit Detect Input: This input pin is for setting the load voltage where a
short circuit level is defined and detected. To enable slow MOSFET turn-on mode,
connect SCD to VC. Connect to load point for minimum threshold (0.335V) or use
resistor divider to increase threshold. Grounding pin enables the fast MOSFET turn
on mode.
Over Current Duty Cycle Input: Connecting a capacitor (≤ 20nF) sets the gate off
time once an over-current condition is detected. No capacitor on this pin will result
in minimum off time; 40µs. Pulling this input low will disable Gate drive.
Controller Input Bias: Provides power to the controller. Connect a 1μF capacitor
between VC pin and ground. For high voltage applications connect a shunt resistor
between VC and the input supply. Voltage on this pin is regulated to 15.5V in high
voltage applications.
8
9
SCD
OCT
10
11
12
VC
GND
OV
Ground: This pin is ground for the control circuitry.
Input Over Voltage Input: The OV pin detects when the input is greater than the
Over-Voltage threshold resulting in a low Fault pin. OV “AND” a Forward Current
condition turns the MOSFETs off. The input voltage OV threshold is programmable
through an external resistor divider. Connect OV to GND to disable this function.
Input Under Voltage Input: The UV pin detects when the input is less than the
Under-Voltage threshold resulting in a low Fault pin. The input voltage UV
threshold is programmable through an external resistor divider. During an Under-
Voltage fault, the Gate is pulled low. Connect UV to VC to disable this function.
Negative Sense Input & Clamp- Connect SN to D2 pin. The polarity and
magnitude of the voltage difference between SP and SN provides an indication of
current flow direction through the MOSFETs.
13
14
UV
SN
Package Pin-out
17 Pin LGA (5mm x 7mm)
Top view
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PI2122
Rev1.0
Page 2 of 19
Absolute Maximum Ratings
D1 to D2 (VD1-D2), D1 or D2 to GND
Drain current (ID ) continuous
Drain current (ID ) pulsed (100μs)
(3)
7V
12A,
60A
56°C/W
Thermal Resistance R
VC
θJA
-0.3 to 17.3V/40mA
-0.3 to 8.0V/ 10mA
-0.3 to 17.3V/ 10mA
SP, SN, OV, OCT
UV, SCD, FT
GND
-0.3V/ 5A peak
-65 oC to 150 oC
-40oC to Thermal shutdown
250oC
Storage Temperature
Operating Junction Temperature
Lead Temperature (Soldering, 20 sec)
ESD Rating (In accordance with JEDEC JESD 51-5)
2kV HBM
Electrical Specifications
Unless otherwise specified: -40°C < TJ < 125°C, VC =12V, CVc = 1uF, COCT = 2nF
Parameter
Symbol Min
Typ
Max
Units
Conditions
VC Supply
Operating Supply Range(4)
VVC-GND
IVC
VVC-CLM
RVC
4.5
15
13.2
4.2
V
No VC Limiting Resistors
Normal Operating Conditions
No Faults
Quiescent Current
3.7
mA
Clamp Voltage
15.5
16
7.5
4.5
V
Ω
IVC=10mA
VC Clamp Shunt Resistance
VC Under-voltage Rising Threshold
VC Under-voltage Falling Threshold
VC Under-voltage Hysteresis
Internal Dual N-Channel MOSFETs
Delta IVC=10mA
VVCUVR
VVCUVF
VVCUVHS
4.3
4.15
150
V
4.0
V
mV
In off state I=10uA;
Tj=25°C; Figure 12, page 11
D1 to D2 Breakdown Voltage
VD1-D2
6
6
V
D1 to GND or D2 to GND
Drain Current Continuous
In OFF state I=10uA; Tj=25°C
In ON state; Tj=25°C
ID1-D2
RDSon
12
9
A
In on state, ID=10A; Tj=25°C
VC-V(D2) ≥ 4.0V
D1 to D2 On Resistance
6
mΩ
FAULT
Under-Voltage Rising Threshold
Under-Voltage Falling Threshold
Under-Voltage Threshold Hysteresis
Under-voltage Bias Current
Over-voltage Rising Threshold
Over-voltage Falling Threshold
VUVR
VUVF
VUVHS
IUV
500
475
25
540
mV
mV
mV
μA
440
-1
1
VOVR
VOVF
500
475
540
mV
mV
440
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 3 of 19
Electrical Specifications
Unless otherwise specified: -40°C < TJ < 125°C, VC =12V, CVc = 1uF, COCT = 2nF
Parameter
Symbol Min
Typ
Max
Units
Conditions
FAULT Continued
Over-voltage Threshold Hysteresis
Over-voltage Bias Current
VOV-HS
25
mV
μA
mV
μA
μs
IOV
VFTL
-1
1
Fault Output Low Voltage
200
500
10
IFT=2mA, VC>4.5V
Fault Output High Leakage Current
Fault Delay Time
IFT-LC
tFT-DEL
TFT
VFT=14V
20
40
145
-10
60
Includes output glitch filter
Over Temperature Fault (1)
Over Temperature Fault Hysteresis(1)
°C
TFT-HS
°C
DIFFERENTIAL AMPLIFIER AND COMPARATORS
Common mode input voltage
VC to SN differential(1)
VCM
VVC-SN
VSP-SN
ISP
-0.1
3.5
-50
5.5
V
VCM =SP & SN w/respect to Gnd
V
Differential operating Input Voltage
SP Input Bias Current
125
mV
μA
μA
V
SP-SN
3.5
-37
VCM =1.25V
VCM =1.25V
SP=0V (SN=0)
VCM =3.3V
SN Input Bias Current
ISN
SN (SP) Voltage
VSN
5.5
-2
Reverse Comparator Off Threshold
Reverse Comparator Hysteresis
Reverse Turn-off Delay
VRVS-TH
VRVS-HS
tF&RDLY
VFWD-TH
VFWD-HS
-10
2
-6
3
mV
mV
ns
5
VCM =3.3V
140
5
180
9
VSP-SN = ± 50mV step
VCM =3.3V
Forward Comparator On Threshold
Forward Comparator Hysteresis
2
mV
mV
-5
-3
-2
VCM =3.3V
Forward Over Current Comparator
Threshold
Forward Over Current Comparator
Hysteresis
Forward Over Current to Turn-off
Delay
VOC-TH
VOC-HS
tFOC-DLY
83
-8
90
-6
97
-4
mV
mV
ns
VCM =3.3V
VCM =3.3V
170
200
VSP-SN = ± 50mV step
Over Current Timer: OCT
OCT Charging Source Current
OCT Clamp Voltage
ISL
-10
3.0
μA
V
VOCT = 1.25V
VOCT-CL
VOCT-Hi
VOCT-Lo
TOCT-OFF
VOCT-Lo
IOCTSK
2.0
4.2
No Fault
SP=3.3V, SN=0V
SP=3.3V, SN=0V
FOC fault condition
IOCT = -100uA
OCT Threshold Voltage High
OCT Threshold Voltage Low
OCT OFF Time
1.75
0.875
350
V
V
µs
mV
mA
OCT MOSFET Disable
OCT Discharge Current
500
5
10
VOCT =2.25V SP-SN=100mV
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 4 of 19
Electrical Specifications
Unless otherwise specified: -40°C < TJ < 125°C, VC =12V, CVc = 1uF, COCT = 2nF
Parameter
Symbol Min
Typ
Max
Units
Conditions
SCD
SCD bias current
Iscd
VThSCDR 300
VThSCDF
VThSCDR -
-1
1
μA
mV
mV
VSCD=0V
SCD threshold voltage high
SCD threshold voltage low
340
310
380
VSP-SN=20mV
SCD Hysteresis
25
50
75
mV
VSP-SN=20mV
VThSCDF
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: Thermal resistance characterized on PI2122-EVAL1 evaluation board with 0 LFM airflow.
Note 4: Refer to the Auxiliary Power Supply section in the Application Information section for details on the VC
requirement to fully enhance the internal MOSFET.
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PI2122
Rev1.0
Page 5 of 19
Functional Description:
The PI2122 integrated Cool-ORing product takes
advantage of two different technologies combining 2
3mΩ on-state resistance (Rds(on)) N-channel
MOSFETs with high density control circuitry. The
product can function as an ideal ORing diode in the
high-side of a redundant power system and a load
disconnect switch, significantly reducing power
dissipation and eliminating the need for heatsinking.
capacitor; then begins charging the capacitor again.
and MOSFETs Gate stay low until the OCT pin
Out
reaches the OCT high threshold (VOCT-Hi), then
Out
goes high and the MOSFETs starts to turn on. As
soon as the MOSFETs reaches sufficient gate
voltage for Rds(on) the Clamp Detector asserts and
turns MOSFETs on. If
is still low then the
FOC
MOSFETs Gate will be pulled low and will start a
new off-time cycle of the Over-Current timer.
The PI2122 has two internal MOSFETs in a back-to-
back configuration that has the ability to block
current in both directions.
This configuration
protects the load and the input source, by turning off
the MOSFETs, during Reverse Current, Forward
Over-Current, Under-Voltage, Over-Voltage and
Over-Temperature faults.
Differential Amplifier:
The PI2122 integrates a high-speed low offset
voltage differential amplifier to sense the difference
between the Sense Positive (SP) pin voltage and
Sense Negative (SN) pin voltage with high
resolution. The amplifier output is connected to
three comparators: Reverse comparator, Forward
comparator, and Forward over-current comparator.
Reverse Current Comparator: RVS
The reverse current comparator provides the most
critical function in the controller, detecting negative
voltage caused by reverse current. When the SN
pin is 6mV higher than the SP pin, the reverse
comparator will turn off the MOSFETs in typically
140ns.
The reverse comparator has typically 3mV of
hysteresis referenced to SP-SN.
Forward Current Comparator: FWD
The FWD comparator detects when a forward
current condition exists and SP is 5mV (typical)
positive with respect to SN. When SP-SN is less
than 5mV it will indicate a fault condition on the
Figure 3: OCT block and timing diagram
pin during a light load while maintaining gate
FT
drive to the MOSFETs. The PI2122 will initiate a
gate shutdown if the Forward “AND” the over-voltage
(OV) condition are true.
Short Circuit Detect: SCD
This comparator block input can be connected to the
load directly or programmed to a higher voltage with
a resistor divider. The function allows the user to
define the (Hard Short) voltage level expected if a
non-ideal short circuit occurs at the load. To prevent
damage of the MOSFETs under this condition
(VSCD<335mV) the gate charge current is increased
by a factor of approximately 5 times resulting in a
duty cycle that is approximately 5 times lower, as
determined by the OCT function. This feature
enables distinguishing between a faulted load
versus powering capacitive and low resistive loads
Over-Current Timer: OCT
OCT off-time is set by the capacitor value connected
to this pin as shown in Figure 4.
The OCT block will control the off-time of the
MOSFETs after a FOC fault condition has occurred.
The equivalent block diagram is shown in Figure 3.
As the Set input at the OCT timer goes high,
Out
will go low, pulling MOSFETs Gate low. At the same
time a one shot of 40µs discharges the OCT
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PI2122
Rev1.0
Page 6 of 19
without entering the OCT mode. The pin can be
grounded to provide a low duty cycle mode or pulled
to VC for lower gate current to drive highly capacitive
loads with resulting higher duty cycle mode under
the fault condition. In either case if the resulting
temperature rise of the MOSFET and controller
reach thermal shutdown the thermal time constant of
the package will set a low frequency burst like duty
cycle condition and protect the MOSFETs.
OV:
The Overvoltage (OV) input trip point can be
programmed through an external resistive divider to
monitor the input voltage. The OV comparator
initiates a fault condition and pulls the
pin low
FT
when OV rises above the Overvoltage Rising
Threshold. The PI2122 will turn the MOSFETs off if
the OV and the Forward Current conditions are both
true. The low resistance redundant paths of an
Active ORing system tend to force all the input
sources to the same voltage making it difficult to
identify the noncompliant source. By ANDing OV
with the Forward Current Threshold the
noncompliant source is identified and disconnected
from the system.
Over-Temperature Detection:
The internal Over-Temperature block monitors the
junction temperature of the controller. The Over-
Temperature threshold is set to 145°C with -10°C of
hysteresis.
When the controller temperature
exceeds this threshold, the Over-Temperature circuit
turns the MOSFETs off and initiates a fault condition
and pulls the
pin low. This function will protect
FT
the MOSFETs from thermal runaway conditions.
Fault:
The fault circuit output is an open collector with 40μs
delay to prevent any false triggering. The
will be pulled low when any of the following faults
occurs:
pin
FT
Figure 4: OCT Off time vs. OCT capacitor value
•
•
Reverse Current
Forward Over-Current “AND” clamp detector is
cleared
Forward Low Current “AND” clamp detector is
cleared
VC and Internal Voltage Regulator:
The PI2122 has a separate input (VC) that provides
power to the control circuitry and the internal gate
driver. An internal regulator clamps the VC voltage
to 15.5V.
•
•
•
•
Over Temperature
Input Under-Voltage
Input Over-Voltage “AND” nominal Forward
Current
For high side applications, the VC input should be
4V above the bus voltage to properly enhance the
internal N-channel MOSFET.
The internal regulator circuit has a comparator to
monitor VC voltage and initiates a FAULT condition
when VC is lower than the VC Under-Voltage
Threshold.
•
VC pin Under-Voltage
The Forward Current fault condition occurs when the
MOSFETs gates are high but are not conducting a
significant level of forward current or may indicate
the MOSFETs are shorted either internally or
externally (VD1-D2 < 5mV).
UV:
The Under Voltage (UV) input trip point can be
programmed through an external resistive divider to
monitor the input voltage. When UV falls below the
Under-Voltage Falling Threshold, UV comparator
initiates a fault condition and pulls the FT pin low
and turns off the MOSFETs.
A gate voltage detector prevents FOC or FWD from
initiating a fault when the MOSFET is in an OFF
condition.
The gate to SN voltage has to reach sufficient
voltage to establish the Rds(on) condition before
these faults are detected.
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PI2122
Rev1.0
Page 7 of 19
Figure 5: PI2122 Functional Block Diagram
Figure 6: Typical comparators thresholds and hysteresis values.
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PI2122
Rev1.0
Page 8 of 19
Figure 7: PI2122 Timing diagram for two ORing controllers application
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PI2122
Rev1.0
Page 9 of 19
Figure 8: PI2122 State diagram.
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PI2122
Rev1.0
Page 10 of 19
Typical Characteristics:
Figure 9: FOC comparator threshold vs. temperature.
VCM: Common Mode Voltage.
Figure 10: Reverse comparator threshold vs. temperature.
VCM: Common Mode Voltage.
Figure 11: Controller bias current vs. temperature.
Figure 12: Reverse condition turn-off delay time vs.
temperature.
Figure 14: Internal MOSFETs drain to source
Figure 13: Internal MOSFETs on-state resistance vs.
breakdown voltage vs. temperature.
temperature.
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PI2122
Rev1.0
Page 11 of 19
Thermal Characteristics:
Figure 15: Junction Temperature vs. Input Current
Figure 16: Junction Temperature vs. Input Current
(0LFM)
(200LFM)
Figure 18: PI2122 mounted on PI2122-EVAL1
Figure 17: PI2122 mounted on PI2122-EVAL1
Thermal Image picture, Iout=12A, TA=25°C,
Air Flow=200LFM
Thermal Image picture, Iout=12A, TA=25°C,
Air Flow=0LFM
Figure 19: PI2122 input current de-rating based on maximum TJ=150°C vs. ambient temperature
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 12 of 19
Application Information:
The PI2122 is designed to replace ORing diodes
and load disconnect switchs in high current
VCClamp : Controller clamp voltage, 15.5V
ICmax : Controller maximum bias current, use
redundant power architectures.
Replacing
a
traditional diode with a PI2122 will result in
significant power dissipation reduction as well as
board space reduction, efficiency improvement,
input power source and output protection plus
4.2mA
Example: Vaux 20V to 30V
Vauxmin −VCclamp
20V −15.5V
additional protection features.
This section
Rbias =
=
=1.07KΩ
ICmax
4.2mA
describes in detail the procedure to follow when
designing with the PI2122 Active ORing solution. A
design example is presented for Active ORing with
load disconnect.
2
(30V −15.5V)2
(Vauxmax −VCclamp
)
PdRbias
=
=
=196mW
Rbias
1.07KΩ
Fault Indication:
Internal N-Channel MOSFET BVdss:
In an application when the MOSFETs are turned off
due to a fault, the series parasitic elements in the
circuit may contribute to the MOSFET being exposed
to a voltage higher than its voltage rating. It is
critical to follow best layout practice to minimize
parasitic inductance in the PCB layout especially in
the high current path.
output pin is an open collector and should be
pulled up to the logic voltage or to the controller VC
via a resistor (10KΩ)
FT
Over-Current Timer: OCT
Connect a capacitor, in the range of 1nF to 20nF to
set the off time after over-current shutdown (see
Figure 4).
In Active ORing applications when one of the input
power sources is shorted, a large reverse current is
sourced from the circuit output through the
MOSFETs. Depending on the output impedance of
the system, the reverse current may reach over 60A
in some conditions before the MOSFET is turned off.
Such high current conditions will store energy even
in a small parasitic element. For example: a 1nH
parasitic inductance with 60A reverse current will
generate 1.8µJ (½Li2). When the MOSFETs are
turned off, the stored energy will be released and
produce a high negative voltage ringing at D1. At
the same time the energy stored at D2 of the internal
MOSFETs will be released and produce a voltage
higher than the load voltage. This event will create a
high voltage difference between the drain and
source of the MOSFET. To reduce the magnitude of
the ringing voltage, add a ceramic capacitor very
close to D1 that can react to the voltage ringing
frequency and another capacitor close to D2.
Recommended values for the ceramic capacitors are
1µF; refer to C5 and C7 in Figure 24.
Short Circuit Detect: SCD
Connect SCD pin to VC to avoid high inrush current
into a capacitive load, or connect SCD to GND pin
for fast turn on. The internal MOSFETs gate drive
current has two levels based on the SCD voltage
level.
Auxiliary Power Supply (Vaux):
Vaux is an independent power source required to
supply power to the VC input. The Vaux voltage
should be 4V higher than Vin (redundant power
source output voltage) to fully enhance the internal
MOSFETs.
A bias resistor (Rbias) is required if the bias supply
(Vaux) is higher than 15V.
connected between the VC pin and Vaux to limit the
current into the internal shunt regulator.
Rbias should be
Minimize the resistor value for low Vaux voltage
levels to avoid a voltage drop that may reduce the
VC voltage lower than required to drive the gate of
the internal MOSFETs.
Select the value of Rbias using the following
equations:
Note:
Since the two MOSFETs are connected in to back-
to-back configuration, the maximum breakdown
voltage is BVdss of one MOSFET plus one diode
forward voltage.
Vauxmin −VCclamp
Rbias =
ICmax
Rbias maximum power dissipation:
2
OV and UV resistor selection:
(Vauxmax −VCclamp
)
PdRbias
Where:
=
The UV and OV comparator inputs are used to
monitor the input voltage and will indicate a fault
condition when this voltage is out of range. The UV
and OV pins can be configured in two different ways,
either with a divider on each pin, or with a three-
resistor divider to the same node, enabling the
Rbias
Vauxmin : Vaux minimum voltage
Vauxmax : Vaux maximum voltage
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 13 of 19
elimination of one resistor. Under-Voltage is
monitored by the UV pin input and Over-Voltage is
monitored with the OV pin input.
V(UV)
IRa
: UV voltage
current.
:
Ra
Alternatively,
a
two-resistor voltage divider
configuration can be used and is shown in (Figure
21).
The Fault pin (
) will indicate a fault (active low)
FT
when the UV pin is below the threshold or when the
OV pin is above the threshold. The UV and OV
thresholds are 0.50V typical with 25mV hysteresis
and their input current is less than ±1µA. It is
important to consider the maximum current that will
flow in the resistor divider and maximum error due to
UV and OV input current. Set the resistor current to
100µA or higher to maintain 1% accuracy for UV and
OV due to the bias current.
Figure 21: Two-resistor divider configuration
The three-resistor voltage divider configuration for
both UV and OV to monitor the same voltage node
is shown in Figure 20:
The UV resistor voltage divider can be obtained from
the following equations:
V (UVTH )
V (OVTH )
R1UV
=
Ra =
IRUV
IRa
Set R1UV value based on system allowable current
IRUV ≥100μA
⎛
⎞
V (UV )
⎜
⎜
⎟
⎟
R2UV = R1UV
−1
V (UVTH )
⎝
⎠
Where:
Figure 20: UV & OV three-resistor divider
: UV threshold voltage
V (UVTH )
configuration.
:
current
R1UV
IRUV
V (OVTH )
Ra =
IRa
V (UVTH )
R1UV
=
Set Ra value based on system allowable current
V (OVTH )
IRUV
IRa
Set R1OV value based on system allowable current
IRUV ≥100μA
Ra =
IRa
⎛
⎞
V (OV)
V (UV)
⎜
⎜
⎟
⎟
Rb = Ra
−1
⎛
⎞
V (OV )
V (OVTH
⎜
⎜
⎟
⎟
R2OV = R1OV
−1
⎝
⎠
)
⎝
⎠
Where:
V (OVTH
⎛
⎞
V (UV)
: OV threshold voltage
)
⎜
⎟
−1
Rc =
(
Ra + Rb
)
⎜
⎟
VTH
⎝
⎠
:
current
R1OV
IROV
Where:
: UV threshold voltage
: OV threshold voltage
V(UVTH )
V(OVTH )
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 14 of 19
Typical Application Example 1:
Connect an 18nF capacitor between the OCT pin
and the GND pin to achieve the maximum off time
after a forward over-current condition occurs.
Requirement:
Redundant Bus Voltage = 5.0V
Load Current = 8A (assume through each redundant
path)
Maximum Ambient Temperature = 70°C, no air flow
Auxiliary Voltage = 12V (10V to 14V)
SCD pin:
Connect the SCD pin to the GND pin for fast
MOSFET enhancement.
Program UV and OV to monitor input voltage:
Program UV at 4.6V and OV at 5.4V
Use the three-resistor divider configuration:
Solution:
A single PI2122 for each redundant 5V power
source should be used, configured as shown in the
circuit schematic in Figure 22.
IRa = 200μA
500mV
or 2.49kΩ 1%
Ra =
= 2.5kΩ
5.4V
200μA
⎛
⎜
⎞
or 432Ω 1%
Rb = 2.49kΩ
−1 = 433Ω
⎟
4.6V
⎝
⎠
4.6V
⎛
⎝
⎞
⎠
Rc =
(
2.49kΩ + 432Ω
)
−1 = 23.96kΩ
⎜
⎟
500mV
or 24.0kΩ 1%
Power Dissipation and Junction Temperature:
First use Figure 15 (Junction Temperature vs. Input
Current) to find the final junction temperature for 8A
load current at 70°C ambient temperature. In Figure
15 (illustrated in Figure 23) draw a vertical line from
8A to intersect the 70°C ambient temperature line.
At the intersection draw a horizontal line towards the
Y-axis (Junction Temperature). The Junction
Temperature at full load current (8A) and 70°C
ambient is 110°C, assuming the typical θJA=56°C/W.
Rds(on) is 9.0mΩ maximum at 25°C and will
increase as the Junction temperature increases.
From Figure 11, at 110°C Rds(on) will increase by
~29%, then
Figure 22: Two PI2122 in High Side ORing
configuration
Vaux:
Since the Vaux voltage does not exceed the VC pin
clamp voltage, connect the Vaux directly to the VC
pin
SP and SN pins:
Connect each SP pin to the D1 pins and each SN
pin to the D2 pins
pin:
FT
Connect to the supervisor logic input and to the logic
power supply via a 10KΩ resistor.
OCT pin:
Figure 23: Example 1 final junction temperature at
8A/70°C TA
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 15 of 19
maximum at 111°C
Rds(on) = 9mΩ∗1.29=11.61mΩ
Vth.reverse − 6mV
Is.reverse =
=
= −1.0A
Rds(on)
6mΩ
Maximum power dissipation is:
Pdmax = Iin2 ∗Rds(on) = (8A)2 ∗11.61mΩ = 743mW
Forward Over-Current threshold\:
The following procedure demonstrates how to
calculate typical forward current in the internal
MOSFETs to generate a forward over-current fault
condition and turn off the internal MOSFETs at room
temperature (25°C) and typical Rds(on):
Recalculate TJ:w
56°C
⎛
⎞
⎠
T
= 70°C +
∗(8A)2 ∗11.61mΩ =111.6°C
⎜
⎟
J max
W
⎝
Reverse Current Threshold:
VFOC−TH
90mV
The following procedure demonstrates how to
calculate the minimum required reverse current in
the internal MOSFETs to generate a reverse fault
condition and turn off the internal Misfits at room
temperature (25°C) and typical Rds(on):
IFOC
=
=
=15A
Rds(on) 6mΩ
Figure 24: Plot of PI2122 response time to reverse current detection (Example 1, Figure 22)
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 16 of 19
Layout Recommendation:
Use the following general guidelines when designing
printed circuit boards. An example of the typical
land pattern for the PI2122 is shown in Figure 25:
due to reverse current fault conditions. The
inductive kick will produce a high voltage across
the MOSFET. If it is not possible to connect the
power source and D1 pins with a very short
trace or common point, connect a capacitor
(shown as C5 in figure 25), recommended value
1µF, close to the D1 pins and return (ground).
Also for the same reason use C7 in figure 25 at
the output.
•
Make sure to have a solid ground (return) plane
to reduce circuit parasitic.
•
Connect all D1 pads together with a wide trace
to reduce trace parasitics to accommodate the
high current input, and also connect all D2 pads
together with a wide trace to accommodate the
high current output.
•
•
Connect the SP pin to the D1 pins and connect
the SN pin to D2 pins.
Use 1oz of copper or thicker if possible to
reduce trace resistance and reduce power
dissipation.
•
The VC bypass capacitor should be located as
close as possible to the VC and GND pins.
Place the PI2122 and bypass capacitor on the
same layer of the board. The VC pin and CVC
(shown as C2 in Figure 25) PCB trace should
not contain any vias or connect to the ground
plane close to the GND pin.
•
Keep the power source very close to the D1
input pins, any parasitic inductance in the trace
connecting the power source and D1 pins will
have inductive kick when there is high current
dv/dt in the trace when the MOSFETs turn off
Figure 25: PI2122 layout recommendation
Figure 26: PI2122 Mounted on PI2122-EVAL1
Please visit www.picorpower.com for information on PI2122-EVAL1
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 17 of 19
Package Drawing
Thermal Resistance Ratings
Parameter
Symbol
θJA
Typical
Unit
°C/W
°C/W
Maximum Junction-to-Ambient (2)
56
Maximum Junction-to-PCB
14
θJC
Note 2: In accordance with JEDEC JESD 51-5
Ordering Information
Part Number
Package
5x7mm 17-pin LGA
Temperature range
Transport Media
PI2122-00-LGIZ
-40°C to 125°C
T&R
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 18 of 19
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.
Vicor Corporation
25 Frontage Road
Andover, MA 01810
USA
Picor Corporation
51 Industrial Drive
North Smithfield, RI 02896
USA
Customer Service: custserv@vicorpower.com
Technical Support: apps@vicorpower.com
Tel: 800-735-6200
Fax: 978-475-6715
Picor Corporation • picorpower.com
PI2122
Rev1.0
Page 19 of 19
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