LINER LTC4371 Dual negative voltage ideal diode-or controller and monitor Datasheet

LTC4371
Dual Negative Voltage
Ideal Diode-OR Controller
and Monitor
Description
Features
Controls N-Channel MOSFETs to Replace Power
Schottky Diodes
nn Low 15mV Forward Voltage Minimizes Dissipation
nn Withstands > ±300V Transients
nn Fast Turn-Off: <220ns
nn Shunt Regulated for High Voltage Applications
nn 4.5V Minimum Operation
nn Low 350μA Quiescent Current
nn 5mA Gate Pull-Up for 60Hz Applications
nn High Impedance Drain Pins: <10μA Leakage
nn Open Fuse and MOSFET Monitor
nn 10-Pin (3mm × 3mm) DFN and MSOP Packages
nn
Applications
–48V Telecom Power
AdvancedTCA Systems
nn Network Routers and Switches
nn Computer Systems and Servers
nn
nn
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
The LTC®4371 is a two-input negative voltage ideal diode-OR
controller that drives external N-channel MOSFETs as a low
dissipation alternative to Schottky diodes in high power –48V
systems. Low power dissipation and voltage loss eliminates
the need for heatsinks and reduces PC board area. Power
sources can be easily ORed together to increase total system
power and reliability.
The LTC4371 tolerates ±300V transients such as those
experienced during lightning-induced surges and input
supply short-circuit events. The internal shunt regulator
and low 350μA quiescent current allow the use of a large
value dropping resistor to protect the supply pin against
high voltage transients, while the high impedance drain
pins can be similarly protected by high value series resistors without compromising diode operation.
The 220ns reverse current turn-off is achieved by a powerful
2A gate driver with low propagation delay, thereby minimizing
peak reverse current under catastrophic fault conditions. Open
MOSFET and fuse faults are indicated at the FAULTB pin, which
is capable of sinking 5mA to drive an LED or opto isolator.
Typical Application
RTN
–48V/50A Diode-OR
Power Dissipation vs. Load Current
RZ
30k
RDA
20k
VA
–36V TO
–72V
DB
GA
40
FAULTB
GB
SA
SB VSS
RDB
20k
D1
GREEN LED =
MOSFETS GOOD
VOUT
50A LOAD
M1*
POWER DISSIPATION (W)
LTC4371
DA
C1
2.2μF
VDD
VZ
vs Load Current
R1
33k
30
SCHOTTKY DIODE
(SBRT60U100CT)
20
POWER
SAVED
10
M3*
VB
–36V TO
–72V
MOSFET
(2–IPT020N10N3)
M2*
4371 TA01a
M4*
*M1-M4: IPT020N10N3
0
0
10
20
30
CURRENT (A)
40
50
4371 TA01b
4371f
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1
LTC4371
Absolute Maximum Ratings
(Notes 1, 2)
Supply Voltage VDD..................................... –0.3V to 17V
Input Voltage
DA, DB (Note 3)..................................... –40V to 100V
SA, SB................................................... –0.3V to 0.3V
DC Currents
VZ.......................................................................20mA
DA, DB................................................................ ±1mA
Single Pulse Current (6ms) DA, DB.........................10mA
Output Voltages
GA, GB.................................................... –0.3V to VDD
FAULTB................................................... –0.3V to 17V
Operating Ambient Temperature Range
LTC4371C................................................. 0°C to 70°C
LTC4371I..............................................–40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MS Package....................................................... 300°C
Pin Configuration
TOP VIEW
DA 1
10 DB
GA 2
9 GB
SA 3
11
VZ 4
VDD 5
TOP VIEW
DA
GA
SA
VZ
VDD
8 SB
7 FAULTB
6 VSS
1
2
3
4
5
10
9
8
7
6
DB
GB
SB
FAULTB
VSS
MS PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 160°C/W
TJMAX = 125°C, θJA = 43°C/W (NOTE 4)
EXPOSED PAD (PIN 11) PCB VSS CONNECTION OPTIONAL
Order Information (http://www.linear.com/product/LTC4371#orderinfo)
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4371CDD#PBF
LTC4371CDD#TRPBF
LGSD
10-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC4371IDD#PBF
LTC4371IDD#TRPBF
LGSD
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC4371CMS#PBF
LTC4371CMS#TRPBF
LTGSF
10-Lead Plastic MSOP
0°C to 70°C
LTC4371IMS#PBF
LTC4371IMS#TRPBF
LTGSF
10-Lead Plastic MSOP
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2
4371f
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LTC4371
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, IZ = 50µA, VDD = 12.4V, SA = SB = VSS unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
VDD
Input Supply Range
IDD
Input Supply Current
Normal Operation
Gate Fault to VSS ,Strong Pull-Up Disabled
Gate Fault to VSS, Strong Pull-Up Enabled
VZ
MIN
l
4.5
∆VSD = ±0.1V
VZ = 10.4V, ∆VSD = 0.1V, One GATE = VSS
IZ = 50µA, ∆VSD = 0.1V, One GATE = VSS
l
l
l
200
400
4.5
Shunt Regulator Voltage
IZ = 50µA
l
11.8
∆VZ
Shunt Regulator Load Regulation
IZ = 50µA to 10mA
l
VZ(PU)
VZ High Threshold to Enable Strong Gate Pull-Up VDD = VZ Rising
∆VZ(PU)
VZ High Threshold Hysteresis
VZ(PU)
VZ Low Threshold to Enable Strong Gate Pull-Up
∆VSD
Source-Drain Forward Servo Voltage
∆VGATE
Gate Drive (VG – VS)
IG = 0µA, –1µA; ∆VSD = 100mV
IGATE(UP)
Gate Pull-Up Current
IGATE(DN)
l
10.7
TYP
MAX
16
V
300
550
7
450
750
9.5
µA
µA
mA
12.4
14
V
600
mV
11.2
11.8
0.5
VZ Falling
UNITS
V
V
1.15
1.25
l
5
15
l
VDD – 0.2
∆VSD = 100mV, ∆VGATE = 5V
l
–3
–5
–8
mA
Gate Pull-Down Current
Strong Gate Pull-Down Current
∆VSD = –10mV, ∆VGATE = 5V
∆VSD = –100mV, ∆VGATE = 5V
l
l
7
1
10
2
13
3
mA
A
tOFF
Gate Turn-Off Time in Fault Condition
∆VSD = 0.1V Step to –0.4V,
CGATE = 3.3nF, ∆VGATE <1V
l
220
ns
ID
DA, DB Leakage Current
MOSFET Off
MOSFET Open
VD = 80V
VD = –40V
l
l
10
–10
µA
µA
RD
DA, DB Resistance
∆VSD = –50mV to 0.1V
l
1
2
5
MΩ
VBVD
DA, DB Breakdown Voltage
ID = 10mA, 6ms
l
100
130
170
IS
SA, SB Leakage Current
VS = 0V
l
±2
μA
150
200
225
mV
l
∆VSD(FLT) Source-Drain Fault Detection Threshold
l
1.35
25
VDD + 0.1
V
mV
V
V
VFAULTB
FAULTB Output Low
IFAULTB = 5mA
l
0.4
V
IFAULTB
FAULTB Leakage Current
VFAULTB = 16V
l
±1
μA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive; all voltages are referenced to
VSS unless otherwise specified.
Note 3: An internal clamp limits the DA and DB pins to a minimum of
100V above VSS and –40V below VSS. This pin can be safely tied to higher
voltages through a resistance that limits the current below 1mA DC or
10mA for a 6ms transient. Driving this pin with current beyond the clamp
may damage the device.
Note 4: Thermal resistance is specified with exposed pad soldered to a
3-inch by 4.5-inch, four layer FR4 board. If exposed pad is not soldered
θJA = 93°C/W.
4371f
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3
LTC4371
Typical Performance Characteristics
Gate
CurrentVoltage
vs Forward
vs Forward
Drop Voltage
Shunt Regulator Load Regulation
12.75
–45
300
12.63
–30
200
100
0
IGATE (µA)
400
VZ (V)
IDD (uA)
Supply Current
TA = 25°C, unless otherwise noted.
12.50
0
12.38
0
4
8
12
VDD (V)
16
12.25
0.01
0.1
1
IZ (mA)
4371 G01
Drain Current vs Drain Voltage
10
–15
10
15
100
VDD = 12.4V
15
4371 G02
Drain Current vs Drain Voltage
400
0
30
∆VSD (mV)
45
60
4371 G03
Load
CurrentVoltage
vs Forward
vs Forward
Drop Voltage
50
VDD = 12.4V
IPT020N10N3 (2)
7.5
40
200
ID (nA)
ID (µA)
2.5
0.1
0
0
85°C
25°C
–40°C
–0.1
0
40
80
VD (V)
–200
–0.50
4371 G04
Turn-Off Time vs Gate
Capacitance
GATE Capacitance
400
250
VDD = 12.4V
∆VSD = 0.1V TO –0.4V
∆VGATE ≤ 1V
tOFF (ns)
200
100
4
0
0.25
VD (V)
0.50
10
20
30
CGATE (nF)
0
0.75
40
50
4371 G07
10
20
∆VSD (mV)
30
40
4371 G06
Turn-Off Time vs Final Overdrive
(T
VFINAL, VINITIAL = 0.1V)
OFF vs
Final
Overdrive
250
VDD = 12.4V
∆VSD = VINITIAL TO –0.4V
200
200
150
150
100
0
0
4371 G05
VDD = 12.4V
∆VSD = 0.1V TO VFINAL
100
50
50
0
20
Turn-Off
Time vs Initial Overdrive
Initial Overdrive
300
0
–0.25
30
10
85°C
25°C
–40°C
tOFF (ns)
–0.2
–40
tOFF (ns)
LOAD CURRENT (A)
5
0
0.2
0.4
0.6
VINITIAL (V)
0.8
1
4371 G08
0
0
–0.2
–0.4
–0.6
VFINAL (V)
–0.8
–1
4371 G09
4371f
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LTC4371
Pin Functions
DA, DB (Pins 1 and 10): Drain Voltage Kelvin Sense Inputs. DA and DB connect to the drains of the N-channel
MOSFETs. The voltage sensed by SA – DA and SB – DB
is used to control the gate drive and hence the ∆VSD drop
across the MOSFETs, and it is also used for fault detection.
For accurate Kelvin sensing of ∆VSD, connect these pins
as closely as possible to the MOSFET drains. An external
resistor protects the DA and DB pins from transients exceeding 100V. If the LTC4371 is used in a single channel
application, DA and DB may be joined together and operated
in parallel; otherwise connect the unused drain pin to VSS.
Exposed Pad (Pin 11 – DD Package Only): Exposed pad
may be left open or connected to VSS.
FAULTB (Pin 7): Fault Output. Open drain output that pulls
low to indicate that one or both of the external MOSFETs
have failed open. FAULTB can sink up to 5mA to drive an
opto isolator or LED. The maximum allowable pull-up
voltage is 17V. Connect to VSS if unused.
GA, GB (Pins 2 and 9): Gate Drive Outputs. GA and GB
operate between VSS and VDD to control their associated
MOSFET gates and emulate the behavior of a diode. For
∆VSD >15mV, the gate pin drives the MOSFET on, while
∆VSD <15mV produces the opposite effect. With a large
positive ∆VSD, the gate pin pulls up with a strong 5mA
source, while large negative ∆VSD activates a 2A pulldown with a maximum propagation delay of 220ns. If the
LTC4371 is used in a single channel application, the gate
pins may be joined together and operated in parallel to
realize a two-fold increase in gate drive strength; otherwise
the unused gate pin may be left open.
SA, SB (Pins 3 and 8): Source Voltage Kelvin Sense Inputs. SA and SB connect to the sources of the N-channel
MOSFETs. The voltage sensed by SA – DA and SB – DB
is used to control the gate drive and hence the ∆VSD drop
across the MOSFETs, and it is also used for fault detection.
For accurate Kelvin sensing of ∆VSD, connect these pins as
close as possible to the MOSFET sources. If the LTC4371
is used in a single channel application, SA and SB may be
joined together and operated in parallel; otherwise connect
the unused source pin to VSS.
VDD (Pin 5): Positive Supply Voltage Input. Supply VDD
directly from 4.5V to 16V, or in shunt regulated applications connect directly or through a buffer transistor biased
by VZ. When connected directly to VZ, bypass VDD with
2.2μF to VSS. Maximum gate drive voltage is limited to VDD.
VSS (Pin 6): Device Substrate and Negative Supply Voltage. VSS connects to VOUT at the joined sources of the
N-channel MOSFETs.
VZ (Pin 4): Shunt Regulator Supply Input. This pin serves
as a shunt regulator for the VDD pin or as a regulator reference, and operates with a bias of 50μA to 10mA. Bypass
with at least 100nF when used as a reference, and 2.2μF
when connected to the VDD pin. If unused, connect VZ to
VSS. See “Strong Gate Pull-Up” in the Applications Information for details on the relationship between the VZ pin
voltage and gate pin drive strength.
4371f
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5
LTC4371
Block Diagram
RTN
RZ
VA
VB
VDD
VZ
DA
M1
GA
DB
AMPA
–
RDA
15mV
15mV
+–
–+
–
AMPB
GB
RDB
M2
+
+
SA
SB
60V
60V
12.4V
130V
130V
FAULTB
FAULT
DETECTION
VSS
4371 BD
VOUT
6
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LTC4371
Operation
The LTC4371 controls N-channel MOSFETs to emulate two
ideal diodes (see Block Diagram). By sensing the MOSFET’s
source-to-drain voltage drop, amplifiers AMPA and AMPB
control the gate of their respective external MOSFET to act
as an ideal diode with a 15mV forward (∆VSD) drop. With
low load currents, the amplifier regulates the MOSFET gate
near its threshold to maintain a forward drop of 15mV. As
load current increases, the gate voltage is driven higher
to maintain a drop of 15mV. For very large load currents
where the MOSFET gate is driven fully on, the forward drop
rises linearly with current according to RDS(ON) • ILOAD. If
the forward drop is less than 15mV, or if ∆VSD reverses,
the amplifier turns the MOSFET off and the load current
transfers to the other channel.
When the power supply voltages are nearly equal, this
regulation technique ensures that the load current is
smoothly shared between the supplies without oscillation. The current balance depends on the RDS(ON) of the
MOSFETs and the output resistance of the supplies.
In the case of supply failure, such as supply VA, while
conducting most or all of the load current is shorted to
return, a large reverse current flows from return through
M1 to any load capacitance and through M2 to supply VB.
AMPA detects the current reversal and turns off M1 in less
than 220ns. Fast turn-off prevents reverse current from
rising to a damaging level.
The remaining supply VB delivers load current through
the body diode of M2, until the gate is driven on. With
700mV forward drop across M2, AMPB responds quickly
and drives the gate with 5mA pull-up current, limiting
the body diode conduction time to under 100μs. This
minimizes power dissipation arising from switchover and
is especially important in 60Hz AC applications. As the
forward drop reduces, a weaker output stage takes over
and regulates the forward drop, within the limitations of
RDS(ON), to 15mV.
The LTC4371 can be powered in –4.5V to –16V applications by connecting VDD directly to the power supply
return. In higher voltage applications or to guard against
input transients, VZ and VDD can be connected together
and powered from return through a bias resistor, RZ. For
repetitive 5mA gate pull-up current, VDD can be driven
by a buffer biased by VZ. The VZ pin is shunt regulated to
12.4V with respect to VSS with 50μA minimum bias, and
is capable of sinking up to 10mA.
The LTC4371 is designed to withstand high voltage transients exceeding ±300V, such as those experienced during
lightning-induced surges and input supply short circuit
events, without damage. 130V internal clamps protect
drain pins DA and DB against positive spikes. External
resistors RDA and RDB are necessary to limit the peak
clamp current to less than 10mA.
In an application circuit, negative spikes are clamped by
the MOSFET’s body diode to VOUT, such that the drain
pin never sees more than –700mV with respect to VSS. A
safely clamped negative transient on one input manifests
itself as a positive transient on the second input and as
an increased voltage from RTN to VOUT. The bias resistor,
RZ, limits the current into the VZ shunt regulator to less
than 10mA.
A Fault Detection circuit monitors MOSFET ∆VSD; FAULTB
pulls low if ∆VSD of either channel exceeds 200mV while
the gate is driven fully on. This is an indication of an open
circuit MOSFET and can be configured for fuse monitoring by moving the drain pin connection to the input side
of the fuse.
4371f
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7
LTC4371
Applications Information
High availability systems employ parallel connected power
supplies or battery feeds to achieve redundancy and
enhance system reliability. Schottky diodes are a popular
means of ORing these supplies together at the point of load.
The chief disadvantage of Schottky diodes is their significant forward voltage drop and resulting power and
efficiency loss. This drop reduces the available supply
voltage and dissipates significant power. The LTC4371
solves these problems by using an N-channel MOSFET
as a low loss pass element to emulate the behavior of a
diode (see Figure 1).
An internal 12.4V shunt regulator at the VZ pin provides
a means of operating the LTC4371 from higher voltage
supplies. It regulates over a range of 50μA to 10mA. In the
simplest configuration shown in Figure 2, VDD is connected
directly to VZ and biased by resistor RZ from the return.
A 2.2μF decoupling capacitor is required to stabilize the
VZ shunt regulator, and to momentarily provide the 5mA
fast pull-up current at the gate pins as needed.
RTN
RZ
C1
2.2μF
LTC4371
RTN
RZ
30k
VZ
VSS
R1
33k
DA
DB
RDA
20k
VA
–36V TO
–72V
GA
GB
4371 F02
VOUT
C1
2.2μF
VDD
Figure 2. Simplest Solution: VDD Connected Directly to VZ
FAULTB
LTC4371
SA
RDB
20k
M1
IPT020N10N3
SB VSS
D1
GREEN LED
VOUT
25A LOAD
Bias resistor RZ is chosen to bias the shunt regulator
and provide the maximum VDD current at the expected
minimum input voltage according to:
RZ <
VIN(MIN) – VZ(MIN)
IDD(MAX) + 50µA
(1)
4371 F01
VB
–36V TO
–72V
Maximum bias resistor dissipation is calculated from:
M2
IPT020N10N3
Figure 1. –36V to –72V/25A Ideal Diode-OR Controller
The MOSFET is turned on when power passes in the
forward direction (positive current flow from source to
drain), allowing for a low voltage drop from load to supply. In the reverse direction, the MOSFET is turned off to
block current flow. By these means, the MOSFET is made
to approach the function and performance of an ideal
diode. The MOSFET voltage drop, ∆VSD, is sensed by the
DA and SA, or DB and SB pins.
Powering VDD
The LTC4371 is fundamentally a low voltage device operating over a range of 4.5V to 16V at the VDD pin, with
respect to VSS. The gate amplifiers are powered from the
VDD pin and pull-up to within 300mV of VDD.
In low voltage applications such as –5V or –12V, the VDD
pin can be powered directly from return, with VSS connected to VOUT.
8
VDD
VZ
PD(RZ) =
(VIN(MAX) – VZ(MIN) )2
RZ
(2)
The maximum shunt regulator current must not exceed
10mA such that:
RZ >
VIN(MAX) – VZ(MIN)
10mA
(3)
In –48V applications a single 1206 size 30kΩ resistor is
adequate to power the LTC4371. In the application shown
in Figure 1, at 100V (a commonly specified maximum
transient condition) peak dissipation in RZ just exceeds
250mW, while the maximum VZ current is slightly less
than 3mA.
Dissipation rises in certain applications so that a larger
package or multiple series units are necessary to implement RZ. Examples include AC applications where the
gate drivers demand additional current to supply repetitive
For more information www.linear.com/LTC4371
4371f
LTC4371
Applications Information
pulses from the 5mA fast pull-up, applications where the
input operating voltage exceeds 72V and applications with
a wide range of input voltage, particularly those where the
minimum input voltage approaches the operating voltage
of the LTC4371. A wide input voltage range may also result
in a situation where the maximum VZ current calculated
in Equation 3 exceeds 10mA. For these cases an NPN
transistor can be used to buffer the shunt regulator and
power VDD, as shown in Figure 3. Equation 1 becomes:
VIN(MIN) – VZ(MIN)
RZ <
IDD(MAX)
50µA +
β
RG
10Ω
RZ1
Q1
2N3904
VDD
VZ
C1
0.1μF
M1
BSP125 (600V)
LTC4371
VSS
4371 F04
Figure 4. MOSFET Cascode for High Voltage > 250V
Applications with 5mA Gate Pull-Up Current
RZ (or RZ2) may be split into multiple segments in order
to achieve the desired standoff voltage or dissipation.
Whereas 1206 size resistors are commonly rated for 200V
working and 400V peak, pad spacing and circuit board design rules may limit the working rating to as little as 100V.
RZ
Q1
C1
0.1μF
RZ2
VOUT
(4)
RTN
In Figure 3, the voltage drop and power dissipation of Q1
may be augmented by the use of one or more resistors
in series with the collector. The same applies for M1 in
Figure 4.
VDD
VZ
RTN
LTC4371
VSS
4371 F03
VOUT
Figure 3. VDD Connected to VZ with NPN for Repetitive
5mA Gate Pull-Up Current
where 50μA represents the minimum VZ shunt regulator
operating current and β is Q1’s DC current gain.
The maximum power dissipation in RZ and the maximum
VZ current are calculated from Equations 2 and 3. Dissipation in emitter follower Q1 is given by:
PD(Q1) =(VIN(MAX) + VBE – VZ(MIN) )•IDD(MAX)
(5)
In buffered applications, bypass VZ with a 100nF capacitor
to VSS. Bypassing VDD is unnecessary.
For applications at very high voltages, beyond 300V, small
high voltage MOSFETs are more readily available than
bipolar devices and the circuit of Figure 4 is preferred.
RZ, calculated using Equation 4, is split into two parts,
RZ1 and RZ2. RZ1 is sized to produce a 3V drop when
operating at VIN(MIN).
For all applications RZ (or RZ1 + RZ2) must limit the maximum VZ current to less than 10mA, as calculated using
Equation 3. If voltage transients are anticipated, VIN(MAX)
becomes the peak transient voltage. Transient requirements may force the use of Figure 3 or Figure 4 instead
of Figure 2. The peak VZ current may also be reduced
to less than 10mA by filtering, e.g. split RZ (or RZ2) into
two equal parts and connect a bypass capacitor from the
central node to VSS.
Strong Gate Pull-Up
For fast turn-on, a strong 5mA driver pulls up on the gate
when the MOSFET forward drop (∆VSD) is large. In simple
shunt-regulated applications such as shown in Figure 2,
the bias resistor RZ may be incapable of supplying 5mA.
In this case, a 2.2µF bypass capacitor is required to
momentarily provide the strong pull-up current to fully
charge the MOSFET gate. In normal operation the 5mA
drive is not a DC condition, as it flows only long enough
to deliver gate charge to the MOSFET. The amount of
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9
LTC4371
Applications Information
charge is approximately equal to the total gate charge,
Qg, as specified on the MOSFET’s data sheet.
the range of 11.6V to 14.1V, compatible with standard
10V-specified MOSFETs. In low voltage applications,
such as where the VDD pin is directly powered from less
than 10V, the gate drive is compatible with logic-level
and sub logic-level MOSFETs.
If there is a fault wherein the MOSFET gate is shorted to VSS
and ∆VSD is large, the 5mA pull-up becomes a continuous
load on VDD. The extra VDD current overwhelms RZ and
discharges the 2.2µF bypass capacitor. When VZ falls to
the VZ(PU_EN) threshold of 10.7V, the 5mA pull-up current
on both channels is disabled. The 5mA pull-up is enabled
when VZ recovers to 11.2V. This feature prevents a shorted
gate pin from collapsing VDD and, aside from disabling the
5mA pull-up, interfering with the operation of the second
channel when using the configuration shown in Figure 2.
The drain-source breakdown rating, BVDSS, must be greater
than or equal to the highest input supply voltage. If an
input is shorted, the full supply voltage of the opposing
channel will appear across the MOSFET of the shorted
channel. Avalanche may occur during input short circuits
and lightning induced surges if the peak transient voltage
exceeds BVDSS with respect to VOUT.
In applications such as Figure 3 and 4, if the VDD supply is
designed to deliver > 5mA, no VDD bypassing is required.
Note that a shorted gate will demand a continuous current
of 5mA whenever ∆VSD is large.
The LTC4371 attempts to servo the forward drop across
the MOSFET (∆VSD) to 15mV by controlling the gate, and
flags a fault if the drop exceeds 200mV when the MOSFET is
driven fully on. Thus an upper bound for RDS(ON) is set by:
The 5mA pull-up is enabled when VZ is biased to >11.8V
in its normal shunt regulator mode, or when VZ is <1.15V.
Connecting VZ to VSS permanently enables the 5mA gate
pull-up. If VZ is not used as a shunt regulator, the 5mA
pull-up can be disabled by biasing VZ to voltage between
1.35V and 10.4V (with respect to VSS) as shown in Figure 5.
RTN
RZ
510k
RG
10Ω
C1
10nF
VDD
VZ
D2
7.5V
C2
10nF
LTC4371
VSS
ILOAD(MAX)
(6)
Where ∆VSD(FLT) is 150mV minimum.
Further, RDS(ON) must be small enough to conduct the
maximum load current without excessive MOSFET dissipation, which is calculated from:
(7)
The definition of “excessive” is provided by the circuit
designer based on package and circuit board thermal
constraints.
Loop Stability
4371 F05
VOUT
Figure 5. MOSFET Follower for High Voltage > 250V
Applications with 5mA Gate Pull-Up Current Disabled
MOSFET Selection
The LTC4371 drives N-channel MOSFETs to conduct the
load current. The important features of the MOSFETs are
threshold voltage, VGS(TH); maximum drain-source voltage,
BVDSS; and on-resistance, RDS(ON).
Full gate drive for the MOSFETs (∆V GATE ) is
VDD + 100mV/–200mV. When used in shunt regulated
circuits such as shown in Figure 2, full gate drive lies in
10
∆VSD(FLT)
PD(MOSFET) = ILOAD(MAX)2 • RDS(ON)
M1
BSP125
D1
7.5V
RDS(ON) <
The gate amplifiers are compensated by the input capacitance of the external MOSFETs. No further compensation
components are necessary except in the case of very small
MOSFETs. If CISS is less than 500pF, add a 1nF capacitor
across the MOSFET gate and source terminals.
High Voltage Transient Protection
Although the LTC4371 drain pins, DA and DB are designed
to handle voltages ranging from –40V to 100V with respect
to VSS, they may be subjected to much higher voltages,
even in –48V systems. DA and DB are directly exposed to
4371f
For more information www.linear.com/LTC4371
LTC4371
Applications Information
all voltages appearing at the input. Spikes and transients
may arise from various conditions including lightning
induced surges, electrostatic discharge, switching of
adjacent loads, and input short circuits.
The positive spike at the input is clamped to BVDSS relative to VOUT by MOSFET avalanche. BVDSS is inadequate
protection for the DA and DB pins, as shall be discussed
later. Although the energy stored in parasitic inductance
during input short circuit faults is at least two orders of
magnitude smaller than the avalanche energy rating of
most MOSFETs, the peak current may exceed the avalanche
current rating of the MOSFET. In this case and if positivegoing transient energy from other external sources exceeds
the MOSFET’s avalanche energy rating, add TVS clamps
across each MOSFET as shown in Figure 6.
The dynamic behavior of an active ideal diode entering
reverse bias is most accurately characterized by a delay,
followed by a period of reverse recovery. During the delay
phase some reverse current is built up, limited by parasitic
resistance and inductance. During the reverse recovery
phase, energy stored in the parasitic inductance is transferred to other elements in the circuit.
Externally applied input transients in the negative direction are clamped by the body diodes of the MOSFETs to
–700mV with respect to VOUT, if not connected directly
through RDS(ON) to VOUT, and pose no particular hazard
for the DA and DB pins. Negative input transients couple
directly to the output which increases the RTN to VOUT
voltage. Although the shunt resistor, RZ, limits the current
into VZ to a safe level of less than 10mA, an output capacitor or TVS clamp may be required to protect downstream
circuitry from negative input transients.
Current slew rates during reverse recovery may reach
100A/μs or higher. High slew rates coupled with parasitic
inductance in series with the input and output can cause
destructive transients to appear at the drain, source and
VSS pins of the LTC4371 during reverse recovery.
A zero impedance short circuit directly across the input
and return is especially troublesome because it permits
the highest possible reverse current to build up during
the delay phase. When the MOSFET finally interrupts the
reverse current, the MOSFET drain and the LTC4371 drain
pins experience a positive-going voltage spike, while the
MOSFET source and the LTC4371 source and VSS pins
spike in the negative direction. To protect the circuit biasing VDD, clamp or bypass VOUT as close as possible to the
junction of the MOSFET sources and VSS and the point
where the VDD bias circuit connects to return.
100V BVDSS(MIN) MOSFETs are commonly used in –48V
applications, but BVDSS(MAX) is not guaranteed and cannot
be relied upon to protect the DA and DB pins from exceeding their absolute maximum rating of 100V. Nevertheless,
the 100V absolute maximum rating for DA and DB may
be safely exceeded if certain precautions are taken. The
internal 130V clamps shown in the Block Diagram tolerate
RTN
RZ
30k
33k
VDD
VZ
INPUT SHORT
LTC4371
DA
VA
–36V TO
–72V
VB
–36V TO
–72V
INPUT PARASITIC
INDUCTANCE
–
+
20k
DB
GA
CLOAD
FAULTB
GB
SA
GREEN LED =
MOSFETS GOOD
SB VSS
20k
2.2μF
OPT.
OUTPUT PARASITIC
INDUCTANCE
–
+
VOUT
REVERSE
RECOVERY
CURRENT
INPUT PARASITIC
INDUCTANCE
+
–
OPT.
Figure 6. Input Short Circuit Parasitics and Protection Against High Voltage Transients
For more information www.linear.com/LTC4371
4371 F06
4371f
11
LTC4371
Applications Information
up to 10mA for 6ms in breakdown. For protection against
transients exceeding 100V, add series resistors RDA and
RDB according to:
RDA , RDB >
VIN(PK) – VBVD(MIN)
where VIN(PK) is the peak input voltage measured with
respect to VSS, and VBVD(MIN) is the minimum drain pin
breakdown voltage (100V).
Because their presence incurs no particular performance
penalty, a minimum value of 20kΩ is prudent and protects the DA and DB pins against transients up to 300V,
as shown in Figure 7. A practical limit for RDA and RDB
is 100kΩ, beyond which their resistance interferes with
the operation of the gate amplifier. Some speed penalty
is incurred for values greater than 20kΩ, as shown in
Figure 8. If the speed penalty is unacceptable, add a
resistor and capacitor across RDA and RDB as shown in
Figure 9 to restore the response time.
LTC4371
GA
SA
VSS
RDA
20k
VA
DA
GA
VOUT
M1
4371 F07
C1
100pF
VA
tOFF (ns)
4371 F08
Figure 9. High Voltage Drain Pin Protection with C1 and
R1 Maintaining Fast Turn-Off Time
High Voltage DC Applications
An extra blocking device is necessary to protect the DA
and DB pins in applications where the DC input voltage
exceeds 100V. Even in –48V applications the equivalent
DC input voltage may exceed 100V, as a result of a reverse
connected supply feed that can impress up to double the
maximum operating voltage across the inputs.
Because the 130V DA and DB pin clamps are limited to
clamping short-term spikes, some other means of limiting
the maximum applied voltage is necessary in DC applications. The N-channel cascode shown in Figure 10 extends
the DC input operating voltage to 600V. It safely clamps
the drain pin to about 2V less than VZ, yet introduces only
500Ω series resistance when the input is in the vicinity of
VOUT; fast turn-off time is maintained.
RZ
VDD = 12.4V
∆VSD = 0.1V TO –0.4V
CGATE = 3.3nF
VZ
450
LTC4371
DA
300
GA
SA
VSS
D1
IN4148W
150
M2
BSS127
VA
0
20
40
60
80
DRAIN PIN RESISTANCE (kΩ)
100
4371 F09
Figure 8. Reverse Response Time vs. Drain Pin Resistance
12
VOUT
M1
Drain Pin Resistance
0
VSS
RDA
100k
R1
10k
Figure 7. 300V Drain Pin Protection
600
SA
(8)
10mA
DA
LTC4371
M1
VOUT
4371 F10
Figure 10. Drain Protection for Applications Up to –600V
4371f
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LTC4371
Applications Information
Fuse and Open MOSFET Detection
The LTC4371 monitors ∆VSD of each channel as measured
across SA – DA and SB – DB. If ∆VSD of either channel
exceeds 200mV and the associated gate pin is driven fully
on, FAULTB pulls low to indicate a fault. Conditions leading to high ∆VSD include excessive load current (ILOAD ×
RDS(ON) > 200mV), an open circuit MOSFET or an open
fuse placed in series with the MOSFET. A high ∆VSD fault
is detected on only the highest voltage input supply, i.e.
the path that should be supplying power is, as a result of
one of the aforementioned conditions, unable to do so.
Temporary conditions, such as the initial 700mV drop
experienced when an input first rises to the point of supplying current but before the gate has been driven on, are
masked since the gate must also be high for fault detection.
Figure 12 shows a protection method that extends DA and
DB pin operation to ±600V. The drain pins are clamped
by an 82V Zener diode. As shown, the DA pin is clamped
at 82V with respect to VSS in the positive direction, and
700mV below VSS in the negative direction. When a high
input voltage of either polarity is present, back-to-back
depletion mode N-channel MOSFETs limit the current in
the Zener diode to VGS(TH)/RDA (100μA for RDA = 20kΩ),
a value that is indefinitely sustainable.
LTC4371
DA
DB
GA
GB
SA
SB VSS
D1
1N4148W
D2
1N4148W
RDA
20k
VA
–36V TO
–72V
VB
–36V TO
–72V
RDB
20k
F1
VOUT
M1
F2
M2
4371 F11
Figure 11. Fuse and Open MOSFET Detection
VSS
RDA
20k
M2*
VA
M1
*M2, M3: BSP135 (600V) DEPLETION NMOS
VOUT
4371 F12
Figure 12. Back-to-Back Drain Pin Limiter for ±600V
FAULTB Pin
The open drain FAULTB pin pulls low when the ∆VSD of
either channel exceeds 200mV, while its gate is driven
fully on. FAULTB can sink 5mA to drive an LED for visual
indication, or an opto isolator to communicate across an
isolation barrier. The FAULTB pin voltage is limited to 17V
absolute maximum with respect to VSS in the high state
and cannot be pulled up to return except in low voltage
applications.
LTC4371
DA
SA
M3*
The ∆VSD monitor can be used to detect open fuses, as
shown in Figure 11. An open fuse gives the same signature as an open MOSFET: ∆VSD increases beyond 200mV
when the affected input surpasses the opposing channel.
The connection shown in Figure 11 introduces a new
problem: an open fuse and open MOSFET exposes the DA
and DB pins to high negative voltage with respect to VSS.
Diodes D1 and D2 clamp the DA, DB pins from exceeding
the absolute maximum of –40V with respect to VSS.
GA
82V
In Figure 13, the FAULTB pin is used to shunt current away
from a green LED; the LED indicates (illuminates when) no
fault condition is present. The operating voltage is limited
at the low end by the minimum acceptable LED current,
and at the high end by the FAULTB pin’s 5mA capability.
Figure 14 shows a simple implementation driving a red
LED; the LED indicates a fault condition is present. While
this simple configuration works well in –48V applications,
the maximum operating voltage is limited to 100V, the LED
4371f
For more information www.linear.com/LTC4371
13
LTC4371
Applications Information
current varies widely with operating voltage, and dissipation
in the 20kΩ resistor reaches ≈250mW at 72V input. These
shortcomings are eliminated by the slightly more complex
circuit shown in Figure 15. A cascode shields the FAULTB
pin from the high input voltage and dissipates no power
under normal conditions, while the LED current remains
constant regardless of input voltage when indicating a fault.
At 600V, cascode dissipation reaches 600mW maximum.
RTN
LTC4371
R1
33k
FAULTB
VSS
D1
GREEN LED = MOSFETS GOOD
4371 F13
VOUT
Figure 13. FAULTB Drives a Green LED in Shunt Mode
RTN
R1
20k
500mW
Layout Considerations
A sample layout for the LTC4371 DFN package and PGHSOF-8 MOSFET package is shown in Figure 16.
The VDD bypass capacitor C1 provides AC current to the
device; place it as close to VDD and VSS pins as possible.
Connect the gate amplifier input pins, DA, DB, SA and SB,
directly to the MOSFETs’ drain and source terminals using
Kelvin connections for good accuracy. Place the MOSFET
sources as close together as possible, with VSS connecting
at their intersection.
Keep the traces to the MOSFET drains and common source
wide and short. A good rule-of-thumb for minimizing
self-heating effects in the copper traces is to allow at least
1-inch trace width per 50 amperes, for a surface layer of
1-ounce copper. This current density corresponds to a selfheating effect of about 1.3W per square inch. The traces
associated with the power path through the MOSFETs must
have low resistance to maintain good efficiency and low
drop. The resistance of 1-ounce copper is approximately
500μΩ per square.
D1
RED LED = MOSFET BAD
LTC4371
R2
3.9k
FAULTB
VB
VSS
M2
4371 F14
VOUT
Figure 14. FAULTB Drives a Red LED in Series Mode
RTN
RDB
D1
RED LED = MOSFET BAD
M2
BSP125
VDD
LTC4371
C1
VOUT
RDA
R2
10k
LTC4371
FAULTB
VSS
4371 F15
VA
VOUT
M1
–600V MAX
Figure 15. FAULTB Driving an LED in a High Voltage Application
4371 F16
Figure 16. Recommended PCB Layout for M1, M2 and C1
14
4371f
For more information www.linear.com/LTC4371
LTC4371
Applications Information
Design Example
The following design example demonstrates the calculations involved for selecting external components. Consider
a –48V application with a –36V to –72V operating range,
200V peak transient and 25A maximum load current (see
Figure 17).
The simplest configuration is chosen to power VDD, since
this arrangement easily handles the operating conditions
found in a –48V telecom power system. The bias resistor,
RZ, is calculated from Equation 1:
RZ <
36V – 11.8V
= 32.2kΩ
750µA
The maximum voltage drop across the MOSFET is:
∆VSD = 25A • 2mΩ = 50mV
(11)
which is well below the 150mV minimum ∆VSD fault
threshold.
From Equation 7, the maximum power dissipation in the
MOSFET is:
PD(MOSFET) = 25A 2 • 2mΩ = 1.25W
(9)
(12)
a reasonable value for the proposed package.
The nearest lower 5% value is 30kΩ.
The minimum recommended value of 20kΩ is chosen for
RDA and RDB. 20kΩ protects the DA and DB pins to 300V.
The worst case power dissipation in RZ:
PD(RZ) =
Next, choose the N-channel MOSFET. The 100V,
IPT020N10N3 in a PG-HSOF-8 package with RDS(ON) = 2mΩ
(max) offers a good solution.
(72V – 11.8V)2
= 166mW (10)
30k
A 30kΩ 0.25W resistor is selected for RZ. The maximum
VZ current is confirmed from Equation 3 as a safe value
of 2mA. A –200V transient pushes this to 6.3mA, safely
below the maximum allowable VZ current of 10mA.
The LED, D1, requires at least 1mA of current to turn on
fully; therefore, R1 is set to 33k to accommodate the minimum input supply voltage of –36V. The maximum current
is 2mA at –72V, but excursions to 200V give 6mA, slightly
beyond the FAULTB pin’s 5mA capability. This means that
if there is a fault present, a brief glitch might cause a “no
fault” indication during a 200V transient. Since D1 is a
visual indicator, we’ll accept the remote chance of a dim
flash in exchange for the simple circuit solution.
RTN
RZ
30k
VZ
R1
33k
FAULTB
LTC4371
DA
RDA
20k
VA
–36V TO
–72V
VB
–36V TO
–72V
DB
GA
C1
2.2μF
VDD
GB
SA
RDB
20k
M1
IPT020N10N3
M2
IPT020N10N3
SB VSS
D1
GREEN LED = MOSFETS GOOD
VOUT
25A LOAD
4371 F17
Figure 17. –36V to –72V/25A Ideal Diode-OR
4371f
For more information www.linear.com/LTC4371
15
LTC4371
Applications Information
mum IDD of 9.5mA (LTC4371) + 1mA (LED) = 10.5mA,
Equation 4 gives:
As a second design example, consider modifying the
circuit of Figure 17 to handle 300V transients and to drive
a red LED, which illuminates when a fault is present (see
Figure 18). RDA and RDB are sized to handle transients to
300V, so no change in their value is necessary. Modifications are necessary to drive the red LED.
10.5mA
= 525µA
20
36V – 11.8V
RZ <
= 44k
10mA
50uA+
20
IBASE =
A PZTA42, a 300V NPN with a minimum β = 20 is chosen
to supply both the LED and the VDD pin. With a maxi-
(13)
The nearest lower 5% value is 43k.
To produce 1mA LED current with variations in the circuit,
R1 is chosen to be 8.2k.
RTN
RZ
43k
VZ
Q1
PZTA42
VDD
FAULTB
LTC4371
DA
DB
RDA
20k
VA
–36V TO
–72V
VB
–36V TO
–72V
GA
R1
8.2k
D1
RED LED = MOSFET BAD
GB
SA
RDB
20k
M1
IPT020N10N3
SB VSS
C1
0.1μF
VOUT
25A LOAD
M2
IPT020N10N3
4371 F18
Figure 18. –36V to –72V/25A Ideal Diode-OR
16
4371f
For more information www.linear.com/LTC4371
LTC4371
Typical Applications
RTN
RZ
30k
R1
33k
VZ
VDD
FAULTB
LTC4371
DA
DB
GA
GB
SA
SB VSS
2.2µF
D1
GREEN LED = MOSFETS GOOD
RD
20k
VA
–36V TO
–72V
VOUT
100A LOAD
M1 – M4
IPT020N10N3
4371 F19
Figure 19. –36V to –72V Single Channel Parallel Application with 2× Gate Drive
RTN
R2
100Ω
LTC4371
DA DB
C1
2.2µF
VDD
VZ
R1
33k
FAULTB
GB SA SB VSS
GA
D1
GREEN LED = MOSFETS GOOD
M1
VA
–12V
VOUT
100A LOAD
M2
*3×PSMN0R9-3YLD
VB
–12V
M3
M1– M3 PSMN0R9-3YLD
M4
4371 F20
M5
M6
M4 – M6 PSMN0R9-3YLD
Figure 20. –12V/100A Application with 5mA Gate Pull-Up Enabled
4371f
For more information www.linear.com/LTC4371
17
LTC4371
Typical Applications
RTN
RZ
120k
R1
100k
LTC4371
DA
DB
D2
1N4148
C1
2.2μF
VDD
VZ
GA
FAULTB
GB SA SB VSS
D1
GREEN LED = MOSFETS GOOD
D3
1N4148
M3
BSP89
M4
BSP89
VA
–100V TO
–240V
VOUT
5A LOAD
M1
IPB200N25N3
VB
–100V TO
–240V
M2
IPB200N25N3
4371 F21
Figure 21. –100V to –240V/5A Ideal Diode-OR Controller
RTN
RZ
172k
Q1
PZTA42
VDD
VZ
LTC4371
DA
C1
0.1μF
DB
GA
R1
100k
FAULTB
GB SA SB VSS
D2
MMSZ5268BTIG
D1
GREEN LED = FUSES/MOSFETS GOOD
D3
MMSZ5268BTIG
VA
–100V TO
–240V
VB
–100V TO
–240V
M3
BSP129
M5
BSP129
RDA
20k
RDB
20k
M4
BSP129
M6
BSP129
F1
M1
IPB200N25N3
VOUT
5A LOAD
F2
M2
IPB200N25N3
4371 F22
Figure 22. –100V to –240V/5A Ideal Diode-OR Controller with Open Fuse and MOSFET Detection
18
4371f
For more information www.linear.com/LTC4371
LTC4371
Typical Applications
+
RZ
10k
LTC4371
DA
48V
CT
VA
RDA
20k
DB
C1
2.2μF
VDD
VZ
GA
R1
22k
24VDC
4A
FAULTB
GB
SA SB VSS
RDB
20k
+
D1
GREEN LED
= MOSFETS GOOD
CL
4×1000μF
SUNCON ME-WX
–
M1
IPT020N10N3
117VAC
VB
M2
IPT020N10N3
4371 F23
Figure 23. Full Wave Center Tap Rectifier
4371f
For more information www.linear.com/LTC4371
19
LTC4371
Package Description
Please refer to http://www.linear.com/product/4371#packaging for the most recent package drawings.
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661 Rev F)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.50
0.305 ±0.038
(.0197)
(.0120 ±.0015)
BSC
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
10 9 8 7 6
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0.497 ±0.076
(.0196 ±.003)
REF
0° – 6° TYP
GAUGE PLANE
1 2 3 4 5
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.86
(.034)
REF
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
20
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS) 0213 REV F
4371f
For more information www.linear.com/LTC4371
LTC4371
Package Description
Please refer to http://www.linear.com/product/4371#packaging for the most recent package drawings.
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
6
0.40 ±0.10
10
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.75 ±0.05
0.00 – 0.05
5
1
(DD) DFN REV C 0310
0.25 ±0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
4371f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
For more
information
www.linear.com/LTC4371
21
LTC4371
Typical Application
–48V Ideal Diode-OR with Fuse and Open MOSFET Detection
RTN
RZ
30k
LTC4371
DA
C1
2.2μF
VDD
VZ
DB
GA
R1
33k
FAULTB
GB SA SB VSS
D1
GREEN LED = FUSES/MOSFETS GOOD
D2
1N4148W
D3
1N4148W
RDA
20k
RDB
20k
F1
VA
–36V TO
–72V
VOUT
25A LOAD
M1
IPT020N10N3
F2
VB
–36V TO
–72V
M2
IPT020N10N3
4371 TA02
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LTC4354
Negative Voltage Diode-OR Controller and Monitor
Controls Two N-Channel MOSFETs, 1.2µs Turn-Off, –80V Operation
LTC4355
Positive Voltage Diode-OR Controller and Monitor
Controls Two N-Channel MOSFETs, 0.4µs Turn-Off, 80V Operation
LTC4357
Positive Voltage Ideal Diode Controller
Controls Single N-Channel MOSFET, 0.5µs Turn-Off, 80V Operation
LT®4250
–48V Hot Swap Controller
Active Current Limiting, Supplies from –20V to –80V
LTC4251/LTC4251-1/
LTC4251-2
–48V Hot Swap Controllers in SOT-23
Fast Active Current Limiting, Supplies from –15V
LTC4252-1/LTC4252-2/
LTC4252-A1/LTC4252-A2
–48V Hot Swap Controllers in MS8/MS10
Fast Active Current Limiting, Supplies from –15V, Drain Accelerated
Response
LTC4261/LTC4261-2
Negative Voltage Hot Swap Controllers with ADC
and I2C Monitoring
10-Bit ADC, Floating Topology, Adjustable Inrush
22 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTC4371
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTC4371
4371f
LT 0216 • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2016
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