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LM5050-1, LM5050-1-Q1
SNVS629F – MAY 2011 – REVISED DECEMBER 2019
LM5050-1, LM5050-1-Q1 High-Side OR-ing FET Controller
1 Features
3 Description
•
The LM5050-1/-Q1 High Side OR-ing FET Controller
operates in conjunction with an external MOSFET as
an ideal diode rectifier when connected in series with
a power source. This ORing controller allows
MOSFETs to replace diode rectifiers in power
distribution networks thus reducing both power loss
and voltage drops.
1
•
•
•
•
•
•
•
•
Available in Standard and AEC-Q100 Qualified
Versions LM5050Q0MK-1 (up to 150°C TJ) and
LM5050Q1MK-1 (up to 125°C TJ)
Functional safety capable
– Documentation available to aid functional
safety system design
Wide Operating Input Voltage Range, VIN: 1 V to
75 V (VBIAS required for VIN < 5 V)
100-V Transient Capability
Charge Pump Gate Driver for External N-Channel
MOSFET
Fast 50-ns Response to Current Reversal
2-A Peak Gate Turnoff Current
Minimum VDS Clamp for Faster Turnoff
Package: SOT-6 (Thin SOT-23-6)
The LM5050-1/-Q1 controller provides charge pump
gate drive for an external N-Channel MOSFET and a
fast response comparator to turn off the FET when
current flows in the reverse direction. The LM5050-1/Q1 can connect power supplies ranging from 5 V to
75 V and can withstand transients up to 100 V.
Device Information(1)
PART NUMBER
LM5050-1
SOT (6)
LM5050-1-Q1
2 Applications
Active OR-ing
Supplies
of
Redundant
(N+1)
PACKAGE
BODY SIZE (NOM)
2.90 mm × 1.60 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Power
Full Application
VIN
VOUT
+5.0V to +75V
100:
IN
OUT
GATE
VS
LM5050-1
Shutdown
Low= FET On, High= FET Off
OFF
0.1 PF
GND
GND
GND
Typical Redundant Supply Configuration
PS1
IN
GATE OUT
LM5050-1 VS
GND
CLOAD
PS2
IN
RLOAD
GATE OUT
LM5050-1 VS
GND
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM5050-1, LM5050-1-Q1
SNVS629F – MAY 2011 – REVISED DECEMBER 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
6.7
4
4
4
4
4
5
8
Absolute Maximum Ratings ......................................
ESD Ratings: LM5050-1 ..........................................
ESD Ratings: LM5050-1-Q1 .....................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 11
7.1 Overview ................................................................. 11
7.2 Functional Block Diagram ....................................... 12
7.3 Feature Description................................................. 12
7.4 Device Functional Modes........................................ 13
8
Application and Implementation ........................ 14
8.1 Application Information............................................ 14
8.2 Typical Applications ................................................ 16
9 Power Supply Recommendations...................... 21
10 Layout................................................................... 21
10.1 Layout Guidelines ................................................. 21
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
11.5
11.6
Documentation Support ........................................
Related Links ........................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision E (December 2015) to Revision F
•
Page
Added Functional safety capable link to the Features section ............................................................................................... 1
Changes from Revision D (June 2013) to Revision E
•
2
Page
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section ................................................................................................. 1
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
5 Pin Configuration and Functions
DDC Package
6-Pin SOT
Top View
GND 2
OFF 3
LM5050MK-1
VS 1
6 OUT
5 GATE
4 IN
Pin Functions
PIN
NO.
NAME
I/O
DESCRIPTION
The main supply pin for all internal biasing and an auxiliary supply for the internal gate drive
charge pump. Typically connected to either VOUT or VIN; a separate supply can also be used.
1
VS
I
2
GND
PWR
3
OFF
I
A logic high state at the OFF pin will pull the GATE pin low and turn off the external MOSFET.
Note that when the MOSFET is off, current will still conduct through the FET's body diode. This
pin should may be left open or connected to GND if unused.
4
IN
I
Voltage sense connection to the external MOSFET Source pin.
5
GATE
O
Connect to the Gate of the external MOSFET. Controls the MOSFET to emulate a low forwardvoltage diode.
6
OUT
O
Voltage sense connection to the external MOSFET Drain pin.
Ground return for the controller
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LM5050-1, LM5050-1-Q1
SNVS629F – MAY 2011 – REVISED DECEMBER 2019
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
IN, OUT Pins to Ground (2)
GATE Pin to Ground
(2)
MIN
MAX
UNIT
–0.3
100
V
–0.3
100
V
VS Pin to Ground
–0.3
100
V
OFF Pin to Ground
–0.3
7
V
Storage Temperature
−65
150
°C
(1)
(2)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The GATE pin voltage is typically 12 V above the IN pin voltage when the LM5050-1 is enabled (that is, OFF Pin is Open or Low, and
VIN > VOUT). Therefore, the absolute maximum rating for the IN pin voltage applies only when the LM5050-1 is disabled (that is, OFF
Pin is logic high), or for a momentary surge to that voltage because the Absolute Maximum Rating for the GATE pin is also 100 V
6.2 ESD Ratings: LM5050-1
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Machine model (MM) (2)
±150
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
The MM is a 200-pF capacitor discharged through a 0-Ω resistor (that is, directly) into each pin. Applicable test standard is JESD-A115A.
6.3 ESD Ratings: LM5050-1-Q1
VALUE
V(ESD)
(1)
(2)
Human-body model (HBM), per AEC Q100-002
Electrostatic discharge
(1)
±2000
Machine model (MM) (2)
UNIT
V
±150
AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
The MM is a 200-pF capacitor discharged through a 0-Ω resistor (that is, directly) into each pin. Applicable test standard is JESD-A115A.
6.4 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
MAX
UNIT
IN, OUT, VS Pins
5
75
OFF Pin
0
5.5
V
Standard Grade
−40
125
°C
LM5050Q0MK-1
−40
150
°C
LM5050Q1MK-1
−40
125
°C
Junction Temperature (TJ)
V
6.5 Thermal Information
LM5050-1/-Q1
THERMAL METRIC (1)
DDC (SOT)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance
180.7
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
41.3
°C/W
RθJB
Junction-to-board thermal resistance
28.2
°C/W
ψJT
Junction-to-top characterization parameter
0.7
°C/W
ψJB
Junction-to-board characterization parameter
27.8
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
Thermal Information (continued)
LM5050-1/-Q1
THERMAL METRIC (1)
DDC (SOT)
UNIT
6 PINS
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
°C/W
6.6 Electrical Characteristics
Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless
otherwise stated the following conditions apply: VIN = 12 V, VVS = VIN, VOUT = VIN, VOFF = 0 V, CGATE= 47 nF, and TJ = 25°C.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VS PIN
Operating
Supply Voltage
Range
VVS
TJ = –40°C to 125°C
VVS= 5 V, VIN = 5 V
VOUT = VIN - 100 mV
Operating
Supply Current
IVS
5
TJ = 25°C
75
V
75
TJ = –40°C to 125°C
105
VVS= 12 V, VIN = 12 V TJ = 25°C
VOUT = VIN - 100 mV
TJ = –40°C to 125°C
100
VVS= 75 V, VIN = 75 V TJ = 25°C
VOUT = VIN - 100 mV
TJ = –40°C to 125°C
130
147
μA
288
IN PIN
Operating Input
Voltage Range
VIN
TJ = –40°C to 125°C
VIN = 5 V
VVS= VIN
VOUT = VIN - 100 mV
GATE = Open
IIN
IN Pin current
VIN = 12 V to 75 V
VVS= VIN
VOUT = VIN - 100 mV
GATE = Open
5
TJ = 25°C
75
V
190
TJ = –40°C to 125°C
32
TJ = 25°C
305
μA
320
TJ = –40°C to 125°C
LM5050MK-1,
LM5050Q1MK-1
233
400
TJ = –40°C to 125°C
LM5050Q0MK-1
233
475
5
75
OUT PIN
VOUT
Operating
Output Voltage
Range
VIN = 5 V to 75 V
OUT Pin Current VVS= VIN
VOUT = VIN - 100 mV
TJ = 25°C
IOUT
VIN = 5 V
VVS = VIN
VGATE = VIN
Gate Pin Source VOUT = VIN - 175 mV
Current
VIN = 12 V to 75 V
VVS = VIN
VGATE = VIN
VOUT = VIN - 175 mV
TJ = 25°C
VIN = 5 V
VVS = VIN
VOUT = VIN - 175 mV
TJ = 25°C
VIN = 12 V to 75 V
VVS = VIN
VOUT = VIN - 175 mV
TJ = 25°C
TJ = –40°C to 125°C
V
3.2
TJ = –40°C to 125°C
8
µA
GATE PIN
IGATE(ON)
VGS
(1)
VGATE - VIN in
Forward
Operation (1)
TJ = –40°C to 125°C
30
12
TJ = 25°C
TJ = –40°C to 125°C
TJ = –40°C to 125°C
TJ = –40°C to 125°C
41
µA
32
20
41
7
4
9
V
12
9
14
Measurement of VGS voltage (that is. VGATE - VIN) includes 1 MΩ in parallel with CGATE.
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
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Electrical Characteristics (continued)
Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless
otherwise stated the following conditions apply: VIN = 12 V, VVS = VIN, VOUT = VIN, VOFF = 0 V, CGATE= 47 nF, and TJ = 25°C.
PARAMETER
tGATE(REV)
Gate
Capacitance
Discharge Time
at Forward to
Reverse
Transition
See Figure 1
TEST CONDITIONS
MIN
TJ = 25°C
CGATE = 0 (2)
CGATE = 47 nF (2)
tGATE(OFF)
CGATE = 47 nF (3)
IGATE(OFF)
Gate Pin Sink
Current
VGATE = VIN + 3 V
VOUT > VIN + 100 mV
t ≤ 10 ms
VSD(REV)
Reverse VSD
Threshold
VIN < VOUT
ΔVSD(REV)
Reverse VSD
Hysteresis
60
TJ = 25°C
180
TJ = –40°C to 125°C
VSD(REG)
TJ = 25°C
486
ns
2.8
TJ = –40°C to 125°C
LM5050MK-1,
LM5050Q1MK-1
1.8
TJ = –40°C to 125°C
LM5050Q0MK-1
1.4
A
–28
TJ = –40°C to 125°C
–41
–16
TJ = 25°C
10
TJ = 25°C
19
mV
mV
TJ = –40°C to 125°C
LM5050MK-1,
LM5050Q1MK-1
1
37
TJ = –40°C to 125°C
LM5050Q0MK-1
1
60
TJ = 25°C
VIN = 12 V
VVS = VIN
VIN - VOUT
ns
350
TJ = 25°C
VIN = 5 V
VVS = VIN
VIN - VOUT
UNIT
85
TJ = 25°C
TJ = 25°C
VIN - VOUT
MAX
25
TJ = –40°C to 125°C
CGATE = 10 nF (2)
Gate
Capacitance
DischargeTime
at OFF pin Low
to High
Transition
See Figure 2
Regulated
Forward VSD
Threshold
VIN > VOUT
TYP
22
TJ = –40°C to 125°C
LM5050MK-1,
LM5050Q1MK-1
4.4
37
TJ = –40°C to 125°C
LM5050Q0MK-1
4.4
60
mV
OFF PIN
VOFF(IH)
OFF Input High
Threshold
Voltage
VOUT = VIN-500 mV
VOFF Rising
VOFF(IL)
OFF Input Low
Threshold
Voltage
VOUT = VIN - 500 mV
VOFF Falling
ΔVOFF
OFF Threshold
Voltage
Hysteresis
VOFF(IH) - VOFF(IL)
IOFF
OFF Pin Internal VOFF = 4.5 V
Pulldown
VOFF = 5 V
(2)
(3)
6
TJ = 25°C
1.56
TJ = –40°C to 125°C
1.75
TJ = 25°C
V
1.4
TJ = –40°C to 125°C
1.1
TJ = 25°C
155
TJ = 25°C
5
TJ = –40°C to 125°C
3
TJ = 25°C
mV
7
µA
8
Time from VIN-VOUT voltage transition from 200 mV to -500 mV until GATE pin voltage falls to VIN + 1 V. See Figure 1.
Time from VOFF voltage transition from 0 V to 5 V until GATE pin voltage falls to VIN + 1 V. See Figure 2
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
VIN - VOUT
200 mV
VSD(REG)
0 mV
VIN > VOUT
VSD(REV)
VIN < VOUT
-500 mV
VGATE - VIN
tGATE(OFF)
VGATE
1.0V
0.0V
Figure 1. Gate OFF Timing for Forward to Reverse Transition
VOFF
5.0V
VOFF(IH)
VOFF(IL)
0.0V
VGATE - VIN
tGATE(OFF)
VGATE
1.0V
0.0V
Figure 2. Gate OFF Timing for OFF Pin Low to High Transition
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
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6.7 Typical Characteristics
Unless otherwise stated: VVS = 12 V, VIN = 12 V, VOFF = 0 V, and TJ = 25°C
8
Figure 3. IIN vs VIN
Figure 4. IIN vs VIN
Figure 5. IOUT vs VOUT
Figure 6. IOUT vs VOUT
Figure 7. IVS vs VVS
Figure 8. IVS vs VVS
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
Typical Characteristics (continued)
Unless otherwise stated: VVS = 12 V, VIN = 12 V, VOFF = 0 V, and TJ = 25°C
Figure 9. (VGATE - VIN) vs VIN, VVS = VOUT
26
Figure 10. (VGATE - VIN) vs VIN, VVS = VOUT
26
Vin
Vout
Vgate
24
22
22
20
VOLTS (V)
VOLTS (V)
Vin
Vout
Vgate
24
18
16
20
18
16
14
14
12
12
10
10
-5
0
5
10
15
20
TIME (5ms / DIV)
25
30
-50
0
50
100 150
TIME (50ns / DIV)
200
250
Figure 11. Forward CGATE Charge Time, CGATE = 47 nF
Figure 12. Reverse CGATE Discharge, CGATE = 47 nF
Figure 13. VGATE - VIN vs Temperature
Figure 14. tGATE(REV) vs Temperature
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Typical Characteristics (continued)
Unless otherwise stated: VVS = 12 V, VIN = 12 V, VOFF = 0 V, and TJ = 25°C
10
Figure 15. OFF Pin Thresholds vs Temperature
Figure 16. OFF Pin Pulldown vs Temperature
Figure 17. CGATE Charge and Discharge vs OFF Pin
Figure 18. OFF Pin, ON to OFF Transition
Figure 19. OFF Pin, OFF to ON Transition
Figure 20. GATE Pin vs (RDS(ON) × IDS)
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
7 Detailed Description
7.1 Overview
Blocking diodes are commonly placed in series with supply inputs for the purpose of ORing redundant power
sources and protecting against supply reversal. The LM5050 replaces diodes in these applications with an NMOSFET to reduce both the voltage drop and power loss associated with a passive solution. At low input
voltages, the improvement in forward voltage loss is readily appreciated where headroom is tight, as shown in
Figure 2. The LM5050 operates from 5 V to 75 V and it can withstand an absolute maximum of 100 V without
damage. A 12-V or 15-A ideal diode application is shown in Figure 24. Several external components are included
in addition to the MOSFET, Q1. Ideal diodes, like their non-ideal counterparts, exhibit a behavior known as
reverse recovery. In combination with parasitic or intentionally introduced inductances, reverse recovery spikes
may be generated by an ideal diode during an reverse current shutdown. D1, D2 and R1 protect against these
spikes which might otherwise exceed the LM5050 100-V survival rating. COUT also plays a role in absorbing
reverse recovery energy. Spikes and protection schemes are discussed in detail in the Short Circuit Failure of an
Input Supply section.
NOTE
The OFF pin may be used to active the GATE pull down circuit and turn off the pass
MOSFET, but it does not disconnect the load from the input because Q1’s body diode is
still present.
If Vs is powered while IN is floating or grounded, then about 0.5mA will leak from the Vs
pin into the IC and about 3mA will leak from the OUT pin into the IC. From this leakage,
about 50 uA will flow out of the IN pin and the rest will flow to ground. This does not affect
long term reliability of the IC, but may influence circuit design. See Reverse Input Voltage
Protection With IQ Reduction for details on how to avoid this leakage current.
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7.2 Functional Block Diagram
INPUT
LOAD
IN
GATE
OUT
14V
30 µA
30 mV
+ -
35 µA
30 mV
-
+12V Charge
Pump
2A
MOSFET Off
Reverse
Comparator
+
Bias
Circuitry
VS
OFF
5 µA
+
1.5V
-
GND
LM5050- 1
7.3 Feature Description
7.3.1 IN, GATE, and OUT Pins
When power is initially applied, the load current will flow from source to drain through the body diode of
MOSFET. Once the voltage across the body diode exceeds VSD(REG) then the LM5050-1 begins charging
MOSFET gate through a 32 µA (typical) charge pump current source . In forward operation, the gate of
MOSFET is charged until it reaches the clamping voltage of the 12-V GATE to IN pin Zener diode internal to
LM5050-1.
the
the
the
the
The LM5050-1 is designed to regulate the MOSFET gate-to-source voltage. If the MOSFET current decreases to
the point that the voltage across the MOSFET falls below the VSD(REG) voltage regulation point of 22 mV (typical),
the GATE pin voltage will be decreased until the voltage across the MOSFET is regulated at 22 mV. If the
source-to-drain voltage is greater than the VSD(REG) voltage, the gate-to-source voltage will increase and
eventually reach the 12-V GATE to IN pin Zener clamp level.
12
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SNVS629F – MAY 2011 – REVISED DECEMBER 2019
Feature Description (continued)
If the MOSFET current reverses, possibly due to failure of the input supply, such that the voltage across the
LM5050-1 IN and OUT pins is more negative than the VSD(REV) voltage of -28 mV (typical), the LM5050-1 will
quickly discharge the MOSFET gate through a strong GATE to IN pin discharge transistor.
If the input supply fails abruptly, as would occur if the supply was shorted directly to ground, a reverse current
will temporarily flow through the MOSFET until the gate can be fully discharged. This reverse current is sourced
from the load capacitance and from the parallel connected supplies. The LM5050-1 responds to a voltage
reversal condition typically within 25 ns. The actual time required to turn off the MOSFET will depend on the
charge held by the gate capacitance of the MOSFET being used. A MOSFET with 47 nF of effective gate
capacitance can be turned off in typically 180 ns. This fast turnoff time minimizes voltage disturbances at the
output, as well as the current transients from the redundant supplies.
7.3.2 VS Pin
The LM5050-1 VS pin is the main supply pin for all internal biasing and an auxiliary supply for the internal gate
drive charge pump.
For typical LM5050-1 applications, where the input voltage is above 5 V, the VS pin can be connected directly to
the OUT pin. In situations where the input voltage is close to, but not less than, the 5 V minimum, it may be
helpful to connect the VS pin to the OUT pin through an RC Low-Pass filter to reduce the possibility of erratic
behavior due to spurious voltage spikes that may appear on the OUT and IN pins. The series resistor value
should be low enough to keep the VS voltage drop at a minimum. A typical series resistor value is 100 Ω. The
capacitor value should be the lowest value that produces acceptable filtering of the voltage noise.
If Vs is powered while IN is floating or grounded, then about 0.5 mA will leak from the Vs pin into the IC and
about 3mA will leak from the OUT pin into the IC. From this leakage, about 50 uA will flow out of the IN pin and
the rest will flow to ground. This does not affect long term reliability of the IC, but may influence circuit design.
See Reverse Input Voltage Protection With IQ Reduction for details on how to avoid this leakage current.
Alternately, it is possible to operate the LM5050-1 with VIN value as low as 1 V if the VS pin is powered from a
separate supply. This separate VS supply must be from 5 V and 75 V. See Figure 27.
7.3.3 OFF Pin
The OFF pin is a logic level input pin that is used to control the gate drive to the external MOSFET. The
maximum operating voltage on this pin is 5.5 V.
When the OFF pin is high, the MOSFET is turned off (independent of the sensed IN and OUT voltages). In this
mode, load current will flow through the body diode of the MOSFET. The voltage difference between the IN pin
and OUT pins will be approximately 700 mV if the MOSFET is operating normally through the body diode.
The OFF pin has an internal pulldown of 5 µA (typical). If the OFF function is not required the pin may be left
open or connected to ground.
7.4 Device Functional Modes
7.4.1 ON/OFF Control Mode
The MOSFET can be turned off by asserting the OFF pin high. This mode only disables the MOSFET, but VOUT
is still available through the body diode of the MOSFET.
7.4.2 External Power Supply Mode
The Vs pin of the LM5050 can be operated from 5 V to 75 V as the bias input supply. In this mode VIN voltage
can be as low as 1 V, as shown in Figure 27.
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
Systems that require high availability often use multiple, parallel-connected redundant power supplies to improve
reliability. Schottky OR-ing diodes are typically used to connect these redundant power supplies to a common
point at the load. The disadvantage of using OR-ing diodes is the forward voltage drop, which reduces the
available voltage and the associated power losses as load currents increase. Using an N-channel MOSFET to
replace the OR-ing diode requires a small increase in the level of complexity, but reduces, or eliminates, the
need for diode heat sinks or large thermal copper area in circuit board layouts for high power applications.
PS1
CLOAD
RLOAD
PS2
Figure 21. OR-ing with Diodes
The LM5050-1/-Q1 is a positive voltage (that is, high-side) OR-ing controller that will drive an external N-channel
MOSFET to replace an OR-ing diode. The voltage across the MOSFET source and drain pins is monitored by
the LM5050-1 at the IN and OUT pins, while the GATE pin drives the MOSFET to control its operation based on
the monitored source-drain voltage. The resulting behavior is that of an ideal rectifier with source and drain pins
of the MOSFET acting as the anode and cathode pins of a diode respectively.
PS1
IN
GATE OUT
LM5050-1 VS
GND
CLOAD
PS2
IN
RLOAD
GATE OUT
LM5050-1 VS
GND
Figure 22. OR-ing With MOSFETs
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Application Information (continued)
8.1.1 MOSFET Selection
The important MOSFET electrical parameters are the maximum continuous Drain current ID, the maximum
Source current (that is, body diode) IS, the maximum drain-to-source voltage VDS(MAX), the gate-to-source
threshold voltage VGS(TH), the drain-to-source reverse breakdown voltage V(BR)DSS, and the drain-to-source On
resistance RDS(ON).
The maximum continuous drain current, ID, rating must exceed the maximum continuous load current. The rating
for the maximum current through the body diode, IS, is typically rated the same as, or slightly higher than the
drain current, but body diode current only flows while the MOSFET gate is being charged to VGS(TH).
Gate Charge Time = Qg / IGATE(ON)
1. The maximum drain-to-source voltage, VDS(MAX), must be high enough to withstand the highest differential
voltage seen in the application. This would include any anticipated fault conditions.
2. The drain-to-source reverse breakdown voltage, V(BR)DSS, may provide some transient protection to the OUT
pin in low voltage applications by allowing conduction back to the IN pin during positive transients at the OUT
pin.
3. The gate-to-source threshold voltage, VGS(TH), should be compatible with the LM5050-1 gate drive
capabilities. Logic level MOSFETs, with RDS(ON) rated at VGS(TH) at 5 V, are recommended, but sub-Logic
level MOSFETs having RDS(ON) rated at VGS(TH) at 2.5 V, can also be used.
4. The dominate MOSFET loss for the LM5050-1 active OR-ing controller is conduction loss due to source-todrain current to the output load, and the RDS(ON) of the MOSFET. This conduction loss could be reduced by
using a MOSFET with the lowest possible RDS(ON). However, contrary to popular belief, arbitrarily selecting a
MOSFET based solely on having low RDS(ON) may not always give desirable results for several reasons:
1. Reverse transition detection. Higher RDS(ON) will provide increased voltage information to the LM5050-1
Reverse Comparator at a lower reverse current level. This will give an earlier MOSFET turnoff condition
should the input voltage become shorted to ground. This will minimize any disturbance of the redundant
bus.
2. Reverse current leakage. In cases where multiple input supplies are closely matched it may be possible
for some small current to flow continuously through the MOSFET drain to source (that is, reverse)
without activating the LM5050-1 Reverse Comparator. Higher RDS(ON) will reduce this reverse current
level.
3. Cost. Generally, as the RDS(ON) rating goes lower, the cost of the MOSFET goes higher.
5. The dominate MOSFET loss for the LM5050-1 active OR-ing controller is conduction loss due to source-todrain current to the output load, and the RDS(ON) of the MOSFET. This conduction loss could be reduced by
using a MOSFET with the lowest possible RDS(ON). However, contrary to popular belief, arbitrarily selecting a
MOSFET based solely on having low RDS(ON) may not always give desirable results for several reasons:
a. Selecting a MOSFET with an RDS(ON) that is too large will result in excessive power dissipation.
Additionally, the MOSFET gate will be charged to the full value that the LM5050-1 can provide as it
attempts to drive the Drain to Source voltage down to the VSD(REG) of 22 mV typical. This increased Gate
charge will require some finite amount of additional discharge time when the MOSFET needs to be
turned off.
b. As a guideline, it is suggest that RDS(ON) be selected to provide at least 22 mV, and no more than 100
mV, at the nominal load current.
c. (22 mV / ID) ≤ RDS(ON) ≤ (100 mV / ID)
d. The thermal resistance of the MOSFET package should also be considered against the anticipated
dissipation in the MOSFET to ensure that the junction temperature (TJ) is reasonably well controlled,
because the RDS(ON) of the MOSFET increases as the junction temperature increases.
6. PDISS = ID2 × (RDS(ON))
7. Operating with a maximum ambient temperature (TA(MAX)) of 35°C, a load current of 10 A, and an RDS(ON) of
10 mΩ, and desiring to keep the junction temperature under 100°C, the maximum junction-to-ambient
thermal resistance rating (θJA) must be:
a. RθJA ≤ (TJ(MAX) - TA(MAX))/(ID2 × RDS(ON))
b. RθJA ≤ (100°C - 35°C)/(10 A × 10 A × 0.01 Ω)
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Application Information (continued)
c. RθJA ≤ 65°C/W
8.1.2 Short Circuit Failure of an Input Supply
An abrupt 0-Ω short circuit across the input supply will cause the highest possible reverse current to flow while
the internal LM5050-1 control circuitry discharges the gate of the MOSFET. During this time, the reverse current
is limited only by the RDS(ON) of the MOSFET, along with parasitic wiring resistances and inductances. Worst
case instantaneous reverse current would be limited to:
ID(REV) = (VOUT - VIN) / RDS(ON)
(1)
The internal Reverse Comparator will react, and will start the process of discharging the Gate, when the reverse
current reaches:
ID(REV) = VSD(REV) / RDS(ON)
(2)
When the MOSFET is finally switched off, the energy stored in the parasitic wiring inductances will be transferred
to the rest of the circuit. As a result, the LM5050-1 IN pin will see a negative voltage spike while the OUT pin will
see a positive voltage spike. The IN pin can be protected by diode clamping the pin to GND in the negative
direction. The OUT pin can be protected with a TVS protection diode, a local bypass capacitor, or both. In low
voltage applications, the MOSFET drainto- source breakdown voltage rating may be adequate to protect the
OUT pin (that is, VIN + V(BR)DSS(MAX) < 75 V ), but most MOSFET data sheets do not ensure the maximum
breakdown rating, so this method should be used with caution.
Parasitic
Inductance
Reverse Recovery Current
Parasitic
Inductance
COUT
IN
LM5050-1
Shorted
Input
CLOAD
GATE OUT
GND
VS
Figure 23. Reverse Recovery Current Generates Inductive Spikes at VIN and VOUT pins.
8.2 Typical Applications
8.2.1 Typical Application With Input and Output Transient Protection
Q1
SUM40N10-30
VIN
48V
S
CIN
1 PF
75V
D1
SS16T3
VOUT
D
G
IN
GATE
OUT
R1
100:
VS
LM5050-1
OFF/ON
OFF
+ COUT
22 PF
63V
D2
SMBJ60A
C1
0.1 PF
100V
GND
GND
GND
Figure 24. Typical Application With Input and Output Transient Protection Schematic
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Typical Applications (continued)
8.2.1.1 Design Requirements
Table 1 shows the parameters for Figure 24
Table 1. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Minimum Input Voltage, VINMIN
6V
Maximum Input Voltage, VINMax
50 V
Output Current Range, IOUT
0 to 15 A
Ambient Temperature Range, TA
0°C to 50°C
8.2.1.2 Detailed Design Procedure
The following design procedure can be used to select component values for the LM5050-1.
8.2.1.2.1 Power Supply Components (R1 C1,) Selection
The LM5050-1 VS pin is the main supply pin for all internal biasing and an auxiliary supply for the internal gate
drive charge pump. The series resistor (R1) value should be low enough to keep the VS voltage drop at a
minimum. A typical series resistor value is 100 Ω. The capacitor value (0.1 uF typical) should be the lowest value
that produces acceptable filtering of the voltage noise.
8.2.1.2.2 MOSFET (Q1) Selection
The MOSFET (Q1) selection procedure is explained in detail in MOSFET Selection. The MOSFET used in the
design example is SUM40N10-30-E3.
8.2.1.2.3 D1 and D2 Selection for Inductive Kick-Back Protection
Diode D1 and capacitor C1 and diode D2 and capacitor C2 in the Figure 27 serve as inductive kick-back
protection to limit negative transient voltage spikes generated on the input when the input supply voltage is
abruptly shorted to zero volts. As a result, the LM5050-1 IN pin will see a negative voltage spike while the OUT
pin will see a positive voltage spike. The IN pin can be protected by schottky diode (D1) clamping the pin to GND
in the negative direction, similarly the OUT pin should be protected with a TVS protection diode (D1), or with a
local bypass capacitor, or both. D1 is selected as 1-A, 60-V Schottky Barrier Rectifier (SS16T3G) and D2 is the
60 V, TVS (SMBJ60A-13-F).
8.2.1.3 Application Curves
Figure 25. Forward voltage (VIN-VOUT) Drop Reduces
When Gate is Enabled (VIN = 12 V)
Figure 26. Forward Voltage (VIN-VOUT) Drop Increases
When Gate is Disabled (VIN = 12 V)
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8.2.2 Using a Separate VS Supply for Low Vin Operation
In some applications, it is desired to operate LM5050-1 from low supply voltage. The LM5050-1 can operate with
a 1-V rail voltage, provided its VS pin is biased from 5 V to 75 V. The detail of such application is depicted in
Figure 27.
VBIAS
5.0V to 75V
GND
Q1
VIN
VOUT
1V to 75V
C1
1.0 PF
100V
R1
100
D1
IN
GATE
+
OUT
VS
LM5050-1
Off/On
C3
0.1 PF
100V
OFF
GND
C2
22 PF
100V
D2
TVS
82V
GND
GND
Figure 27. Using a Separate vs Supply for Low Vin Operation Schematic
8.2.3 ORing of Two Power Sources
CLOAD
PS1
IN
GATE OUT
RLOAD
LM5050-1
VS
GND
COUT
PS2
IN
GATE OUT
LM5050-1
VS
GND
Figure 28. ORing of Two Power Sources
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8.2.4 Reverse Input Voltage Protection With IQ Reduction
If Vs is powered while IN is floating or grounded, then about 0.5 mA will leak from the Vs pin into the IC and
about 3 mA will leak from the OUT pin into the IC. From this leakage, about 50 uA will flow out of the IN pin and
the rest will flow to ground. This does not affect long term reliability of the IC, but may influence circuit design.
In battery powered applications, whenever LM5050-1 functionality is not needed, the supply to the LM5050-1 can
be disconnected by turning “OFF” Q2, as shown in Figure 29. This disconnects the ground path of the LM5050-1
and eliminates the current leakage from the battery.
The quiescent current of LM5050-1 can be also reduced by disconnecting the supply to VS pin, whenever
LM5050-1 function is not need.
Q1
SUM40N10-30
VIN
48V
VOUT
IN
GATE
OUT
VS
D1
LM5050-1
SS16T3
CIN
1uF
75V
R1
100»
Cout
GND
22uF
63V
D2
BAS40-7-F
D3
SS16T3
D4
SMBJ60A
C1
0.1µF
100V
Q2
NTR5198NLT3G
ON/OFF
Control
GND
GND
Figure 29. Reverse Input Voltage Protection With IQ Reduction Schematic
8.2.5 Basic Application With Input Transient Protection
Q1
SUM40N10-30
VIN
5.0V to 75V
S
CIN
1 PF
100V
D1
B180-13-F
VOUT
D
G
IN
GATE
OUT
VS
LM5050-1
OFF
OFF/ON
GND
GND
GND
Figure 30. Basic Application With Input Transient Protection Schematic
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8.2.6 48-V Application With Reverse Input Voltage (VIN = –48 V) Protection
Q1
SUM40N10-30
VIN
48V
S
CIN
1 PF
75V
VOUT
D
D1
SS16T3
G
IN
GATE
R1
100:
OUT
VS
LM5050-1
OFF
GND
+ COUT
22 PF
63V
D2
SMBJ60A
C1
0.1 PF
100V
D3
SS16T3
GND
GND
Figure 31. 48-V Application With Reverse Input Voltage (VIN = –48 V) Protection Schematic
8.2.6.1 Application Curves
Figure 32. Operation With Positive Polarity Input With
(VIN = 25 V)
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Figure 33. Operation With Negative polarity Input With
(VIN = –25 V)
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9 Power Supply Recommendations
When the LM5050-1/-Q1 shuts off the external MOSFET, transient voltages will appear on the input and output
due to reverse recovery, as discussed in Short Circuit Failure of an Input Supply.To prevent LM5050-1 and
surrounding components from damage under the conditions of a direct input short circuit, it is necessary to clamp
the negative transient at IN, and OUT pins with TVS.
10 Layout
10.1 Layout Guidelines
The typical PCB layout for LM5050-1/-Q1 is shown in Figure 34. TI recommends connecting the IN, Gate and
OUT pins close to the source and drain pins of the MOSFET. Keep the traces of the MOSFET drain wide and
short to minimize resistive losses. Place surge suppressors (D1 and D4) components as shown in the example
layout of LM5050-1 in Layout Example.
10.2 Layout Example
R1
VOUT
D
IN
OFF
LM5050-1
S
D1
CIN
GND
VIN
D4
COUT
C1
G
VS
OUT
GND Gate
Figure 34. Typical Layout Example With D2PAK N-MOSFET
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
Achieving Stable VGS Using LM5050-1 with Low Current and Noisy Input Supply, SLVA684
11.2 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 2. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
LM5050-1
Click here
Click here
Click here
Click here
Click here
LM5050-1-Q1
Click here
Click here
Click here
Click here
Click here
11.3 Community Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LM5050MK-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SZHB
LM5050MKX-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SZHB
LM5050Q0MK-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 150
SL5B
LM5050Q0MKX-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 150
SL5B
LM5050Q1MK-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SP3B
LM5050Q1MKX-1/NOPB
ACTIVE
SOT-23-THIN
DDC
6
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SP3B
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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