LTC4252-2IMS#TRPBF [Linear]
LTC4252/LTC4252A - Negative Voltage Hot Swap Controllers; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C;型号: | LTC4252-2IMS#TRPBF |
厂家: | Linear |
描述: | LTC4252/LTC4252A - Negative Voltage Hot Swap Controllers; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C 二极管 控制器 |
文件: | 总14页 (文件大小:185K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC4354
Negative Voltage
Diode-OR Controller
and Monitor
FeaTures
DescripTion
The LTC®4354 is a negative voltage diode-OR controller
that drives two external N-channel MOSFETs. It replaces
two Schottky diodes and the associated heat sink, saving
power and area. The power dissipation is greatly reduced
by using N-channel MOSFETs as the pass transistors.
Power sources can easily be ORed together to increase
total system power and reliability.
n
Controls N-Channel MOSFETs
n
Replaces Power Schottky Diodes
n
Less Than 1µs Turn-off Time Limits Peak
Fault Current
80V Operation
n
n
Smooth Switchover without Oscillation
n
No Reverse DC Current
n
Fault Output
When first powered up, the MOSFET body diode conducts
the load current until the pass transistor is turned on.
The LTC4354 servos the voltage drop across the pass
transistors to ensure smooth transfer of current from one
transistor to the other without oscillation.
n
Selectable Fault Thresholds
n
Available in 8-Lead (3mm × 2mm) DFN and
8-Lead SO Packages
applicaTions
The MOSFETs are turned off in less than 1µs whenever
the corresponding power source fails or is shorted. Fast
turn-off prevents the reverse current from reaching a level
that could damage the pass transistors.
n
AdvancedTCASystems
n
–48V Distributed Power Systems
n
Computer Systems/Servers
Telecom Infrastructure
Optical Networks
n
n
A fault detection circuit with an open-drain output capable
ofdrivinganLEDoropto-couplerindicateseitherMOSFET
short, MOSFET open or supply failed.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Hot Swap, PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Typical applicaTion
–48V Diode-OR
Power Dissipation vs Load Current
–48V_RTN
6
12k
5
33k
DIODE (MBR10100)
4
V
CC
POWER
SAVED
LOAD
LTC4354
GA
FAULT
3
2
V
SS
DA DB
2k
GB
LED
2k
1µF
1
FET (IRF3710)
V
V
= –48V
= –48V
A
B
4354 TA01
IRF3710
0
0
4
6
8
10
2
CURRENT (A)
IRF3710
4354 TA01b
4354fc
1
LTC4354
absoluTe MaxiMuM raTings (Note 1)
I
(100µs duration)...............................................50mA
Operating Temperature Range
CC
Output Voltages
LTC4354C................................................ 0°C to 70°C
LTC4354I.............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)...................300°C
GA, GB.........................................–0.3V to V + 0.3V
CC
FAULT ...................................................... –0.3V to 7V
Input Voltages
DA, DB................................................... –0.3V to 80V
Input Current
DA, DB Current ................................... –1mA to 20mA
pin conFiguraTion
TOP VIEW
TOP VIEW
DA
1
2
3
4
8
7
6
5
DB
DA
1
2
3
4
8
7
6
5
DB
V
FAULT
GB
SS
CC
V
FAULT
GB
SS
CC
9
V
V
GA
V
SS
GA
V
SS
S8 PACKAGE
8-LEAD PLASTIC SO
DDB PACKAGE
8-LEAD (3mm × 2mm) PLASTIC DFN
T
= 125°C, θ = 150°C/W
JA
JMAX
T
= 125°C, θ = 76°C/W
JA
SS
JMAX
EXPOSED PAD (PIN 9) IS V , CONNECTION TO PCB OPTIONAL
orDer inForMaTion
Lead Free Finish
TAPE AND REEL (MINI)
LTC4354CDDB#TRMPBF
LTC4354IDDB#TRMPBF
TAPE AND REEL
PART MARKING*
LBBK
PACKAGE DESCRIPTION
TEMPERATURE RANGE
0°C to 70°C
LTC4354CDDB#TRPBF
LTC4354IDDB#TRPBF
8-Lead (3mm × 2mm) Plastic DFN
8-Lead (3mm × 2mm) Plastic DFN
LBMB
–40°C to 85°C
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
LEAD FREE FINISH
LTC4354CS8#PBF
LTC4354IS8#PBF
TAPE AND REEL
PART MARKING
4354
PACKAGE DESCRIPTION
8-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
LTC4354CS8#TRPBF
LTC4354IS8#TRPBF
4354I
8-Lead Plastic SO
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
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/
4354fc
2
LTC4354
elecTrical characTerisTics The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. ICC = 5mA, VSS = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
11
MAX
11.75
300
UNITS
l
V
Z
Internal Shunt Regulator Voltage
Internal Shunt Regulator Load Regulation
Operating Voltage Range
I
I
= 5mA
10.25
V
mV
V
CC
CC
∆V
Z
= 2mA to 10mA
200
l
V
CC
4.5
0.5
V
Z
l
l
I
V
Supply Current
V
CC
V
CC
= (V – 0.1V), Note 2
= 5V
1.2
0.8
2
1.1
mA
mA
CC
CC
Z
V
GATE Pins Output High Voltage
GATE Pins Pull-Up Current
V
V
= 10.25V
= 5V
10
10.25
V
V
GATE
CC
CC
4.75
I
V
V
= 60mV; V
= 5.5V
= 5.5V
–15
15
–30
30
–60
60
µA
µA
GATE
SD
SD
GATE
= 0V; V
GATE
l
l
∆V
∆V
Source Drain Sense Threshold Voltage
Source Drain Fault Detection Threshold
Gate Turn-Off Time in Fault Condition
FAULT Pin Output Low
(V – V )
DX
10
30
260
0.7
55
320
1.2
400
1
mV
mV
µs
SD
SS
(V – V ); V = 7V to V
200
SD(FLT)
SS
DX
CC
Z
t
C
= 3300pF; V
≤ 2V; V = –0.4V
GATE SD
OFF
GATE
FAULT
l
l
V
FAULT
I
= 5mA
200
mV
µA
I
I
FAULT Pin Leakage Current
V
= 5V
FAULT
FAULT
D
Drain Pin Input Current
V
V
= 0V
= 80V
–3.5
1.1
–2.5
1.5
–1.5
1.9
µA
mA
DX
DX
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 3: An internal shunt regulator limits the V pin to less than 12V
CC
above V . Driving this pin to voltages beyond the clamp may damage
SS
the part.
Note 4: All currents into pins are positive; all voltages are referenced to
Note 2: I is defined as the current level where the V voltage is lower
V
unless otherwise specified.
CC
CC
SS
by 100mV from the value with 2mA of current.
4354fc
3
LTC4354
Typical perForMance characTerisTics Specifications are at TA = 25°C, ICC = 5mA, VSS = 0V,
unless otherwise noted.
Shunt Regulator Voltage
vs Input Current
Shunt Regulator Voltage
Source Drain Sense Voltage
vs Supply Voltage
vs Input Current at Temperature
12.0
11.5
11.0
10.5
10.0
11.4
11.2
11.0
10.8
10.6
40
35
30
25
20
I
= 10mA
= 5mA
CC
I
CC
I
= 2mA
CC
10
15
20
10
11
0
5
5
6
7
8
9
12
–50 –25
0
25
50
75 100 125
V
(V)
TEMPERATURE (°C)
I
(mA)
CC
CC
4354 G02
4354 G03
4354 G01
Source Drain Sense Voltage
vs Temperature
Gate Turn-Off Time vs Temperature
IGATE(UP) vs ∆VSD
40
35
30
25
20
100
80
60
40
20
0
740
720
700
680
660
–50 –25
0
25
50
75 100 125
30
40
50
60
∆V (mV)
70
80
90
–50 –25
0
25
50
75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
SD
4354 G04
4354 G05
4354 G05
Fault Threshold Voltage
vs Temperature
Drain Pin Current vs Temperature
Drain Pin Current vs Voltage
290
270
250
230
210
–3.2
–3.0
–2.8
–2.6
–2.4
–1
V
= 0V
DX
90°C
25°C
–45°C
–0.75
–0.5
–0.25
0
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
0.3 0.4
0.5 0.6 0.7 0.8 0.9
(V)
1
TEMPERATURE (°C)
TEMPERATURE (°C)
V
DX
4354 G06
4354 G08
4354 G09
4354fc
4
LTC4354
pin FuncTions
DA, DB (Pins 1, 8): Drain Voltage Sense Inputs. These
pinssensesourcedrainvoltagedropacrosstheN-channel
MOSFETs. An external resistor is recommended to pro-
tect these pins from transient voltages exceeding 80V in
extreme fault conditions. For Kelvin sensing, connect
these pins as close to the drains as possible. Connect to
transistorspreventsexcessivereversecurrents.Leavethe
pins open if unused.
V
SS
(Pins 2, 5): Negative Supply Voltage Input. This is the
device negative supply input and connects to the common
source connection of the N-channel MOSFETs. It also
connects to the source voltage sense input of the servo
amplifiers. For Kelvin sensing, connect Pin 5 as close to
the common source terminal of the MOSFETs as possible.
V
if unused.
SS
V
(Pin 3): Positive Supply Voltage Input. Connect this
CC
pin to the positive side of the supply through a resistor.
An internal shunt regulator that can sink up to 20mA
FAULT (Pin 7): Fault Output. Open-drain output that
normally pulls the FAULT pin to V and shunts current
SS
typically clamps V at 11V. Bypass this pin with a 1µF
CC
to turn off an external LED or opto-coupler. In the fault
condition, where the pass transistor is fully on and the
voltage drop across it is higher than the fault threshold,
the FAULT pin goes high impedance, turning on the LED or
opto-coupler. This indicates that one or both of the pass
transistorshavefailedopenorfailedshortcreatingacross
conduction current in between the two power supplies.
capacitor to V .
SS
GA, GB(Pins4, 6):GateDriveOutputs. Gatepinspullhigh
to 10V minimum, fully enhancing the N-channel MOSFET,
when the load current creates more than 30mV of drop
across the MOSFET. When the load current is small,
the gates are actively servoed to maintain a 30mV drop
acrosstheMOSFET.Ifreversecurrentdevelopsmorethan
–140mV of voltage drop across the MOSFET, the pins pull
Connect to V if unused.
SS
EXPOSED PAD (Pin 9): Exposed pad is common to V
and may be left open or connected to Pins 2 and 5.
SS
low to V in less than 1µs. Quickly turning off the pass
SS
FuncTional DiagraM
V
CC
3
BV = 11V
V
SS
5
+
30mV
–
+
–
GA
DA
AMP A
4
1
+
–
30mV
55k
V
SS
+
–
GB
DB
AMP B
6
55k
8
2
FAULT
7
V
SS
V
SS
FAULT DETECTION
V
SS
4354 FD
4354fc
5
LTC4354
TiMing DiagraM
100mV
V
– V
SS
DX
–400mV
2V
V
GATE
t
OFF
4354 TD01
operaTion
High availability systems often employ parallel-connected
power supplies or battery feeds to achieve redundancy
and enhance system reliability. ORing diodes have been
a popular means of connecting these supplies at the
point-of-load. The disadvantage of this approach is the
significant forward-voltage drop and resulting efficiency
loss. This drop reduces the available supply voltage and
dissipates significant power. A desirable circuit would
behave like diodes but without the voltage drop and the
resulting power dissipation.
gate is driven fully on and the voltage drop is equal to the
DS(ON) LOAD
R
• I
.
When the power supply voltages are nearly equal, this
regulation technique ensures that the load current is
smoothly shared between them without oscillation. The
currentlevelflowingthrougheachpasstransistordepends
on the R
of the MOSFET and the output impedance
DS(ON)
of the supplies.
In the case of supply failure, such as if the supply that
is conducting most or all of the current is shorted to the
return side, a large reverse current starts flowing through
the MOSFET that is on, from any load capacitance and
through the body diode of the other MOSFET, to the sec-
ond supply. The LTC4354 detects this failure condition as
soon as it appears and turns off the MOSFET in less than
1µs. This fast turn-off prevents the reverse current from
ramping up to a damaging level.
TheLTC4354isanegativevoltagediode-ORcontrollerthat
drives two external N-channel MOSFETs as pass transis-
torstoreplaceORingdiodes. TheMOSFETsareconnected
together at the source pins. The common source node is
connected to the V pin which is the negative supply of
SS
the device. It is also connected to the positive inputs of
the amplifiers that control the gates to regulate the volt-
age drop across the pass transistors. Using N-channel
MOSFETs to replace Schottky diodes reduces the power
dissipation and eliminates the need for costly heat sinks
or large thermal layouts in high power applications.
In the case where the pass transistor is fully on but the
voltage drop across it exceeds the fault threshold, the
FAULT pin goes high impedance. This allows an LED or
opto-coupler to turn on indicating that one or both of the
pass transistors have failed.
At power-up, the initial load current flows through the
body diode of the MOSFET and returns to the supply with
the lower terminal voltage. The associated gate pin will
immediately start ramping up and turn on the MOSFET.
The amplifier tries to regulate the voltage drop between
the source and drain connections to 30mV. If the load
current causes more than 30mV of drop, the gate rises
to further enhance the MOSFET. Eventually the MOSFET
The LTC4354 is powered from system ground through a
current limiting resistor. An internal shunt regulator that
can sink up to 20mA clamps the V pin to 11V above V .
CC
SS
A 1µF bypass capacitor across V and V pins filters
CC
SS
supply transients and supplies AC current to the device.
4354fc
6
LTC4354
applicaTions inForMaTion
Input Power Supply
The LTC4354 tries to servo the voltage drop across the
MOSFET to 30mV in the forward direction by controlling
the gate voltage and sends out a fault signal when the
voltage drop exceeds the 260mV fault threshold. The
The power supply for the device is derived from –48_RTN
through an external current limiting resistor (R ). An
IN
internal shunt regulator clamps the voltage at V pin to
CC
R
should be small enough to conduct the maximum
DS(ON)
11V. A 1µF decoupling capacitor to V is recommended.
SS
load current while not triggering a fault, and to stay within
It also provides a soft-start to the part.
the MOSFET’s power rating at the maximum load current
2
R
should be chosen to accommodate the maximum
(I • R
).
IN
DS(ON)
supply current requirement of 2mA at the expected input
operating voltage.
Fault Conditions
(VIN(MIN) − VZ(MAX)
)
LTC4354 monitors fault conditions and turns on an LED
or opto-coupler to indicate a fault. When the voltage drop
across the pass transistor is higher than the 260mV fault
threshold, theinternalpull-downattheFAULTpinturnsoff
and allows the current to flow through the LED or opto-
coupler.Conditionsthatcausehighvoltageacrossthepass
transistor include: short in the load circuitry, excessive
load current, FET open while conducting current, and FET
short on the channel with the higher supply voltage. The
fault threshold is internally set to 260mV.
RIN ≤
ICC(MAX)
The power dissipation of the resistor is calculated at the
maximum DC input voltage:
2
(VIN(MAX) − VCC(MIN)
)
P =
RIN
If the power dissipation is too high for a single resistor,
use multiple low power resistors in series instead of a
single high power component.
In the event of FET open on the channel with the more
negative supply voltage, if the voltage difference is high
enough, the substrate diode on the DA or DB pins will
forward bias. The current flowing out of the pins must
be limited to a safe level (<1mA) to prevent device latch
up. Schottky diodes can be used to clamp the voltage at
the DA and DB pins, as shown in Figure 1.
MOSFET SELECTION
The LTC4354 drives N-channel MOSFETs to conduct the
load current. The important features of the MOSFETs are
on-resistanceR
,themaximumdrain-sourcevoltage
DS(ON)
V
, and the threshold voltage.
DSS
The gate drive for the MOSFET is guaranteed to be more
than10Vandlessthan12V.Thisallowstheuseofstandard
threshold voltage N-channel MOSFETs. An external zener
LTC4354
DA
GA
MMBD2836LT1
V
SS
diode can be used to clamp the potential at the V pin
CC
to as low as 4.5V if the gate to source rated breakdown
voltage is less than 12V.
1k
1k
The maximum allowable drain-source voltage, V
(BR)DSS,
must be higher than the supply voltages. If the inputs are
shorted, the full supply voltage will appear across the
MOSFETs.
4354 F01
Figure 1. Method of Protecting the DA and DB Pins from
Negative Inputs. One Channel Shown
4354fc
7
LTC4354
applicaTions inForMaTion
System Power Supply Failure
ESD devices at the DA and DB pins might break down
and become damaged. The external drain resistors limit
the current into the pins and protect the ESD devices. A
2k resistor is recommended for 48V applications. Larger
resistor values increase the source drain sense threshold
voltage due to the input current at the drain pins.
LTC4354 automatically supplies load current from the
system supply with the more negative input potential. If
this supply is shorted to the return side, a large reverse
current flows from its pass transistor. When this reverse
current creates –140mV of voltage drop across the drain
andsourcepinsofthepasstransistor, theLTC4354drives
the gate low fast and turns it off.
Loop Stability
Theservoloopiscompensatedbytheparasiticcapacitance
ofthepowerN-channelMOSFET.Nofurthercompensation
components are normally required. In the case when a
MOSFET with very small parasitic capacitance is chosen,
a 1000pF compensation capacitor connected across the
gate and source pins might be required.
The remaining system power supply will deliver the load
current through the body diode of its pass transistor until
the channel turns on. The LTC4354 ramps the gate up and
turnsontheN-channelMOSFETtoreducethevoltagedrop
across it, a process that takes less than 1ms depending
on the gate charge of the MOSFET.
Design Example
Drain Resistor
The following demonstrates the calculations involved for
selecting components in a –36V to –72V system with 5A
maximum load current, see Figure 2.
Two resistors are required to protect the DA and DB pins
from transient voltages higher than 80V. In the case
when the supply with the lower potential is shorted to the
return side due to supply failure, a reverse current flows
briefly through the pass transistor to the other supply to
dischargetheoutputcapacitor. Thiscurrentstoresenergy
in the stray inductance along the current path. Once the
pass transistor is turned off, this energy forces the drain
terminal of the FET high until it reaches the breakdown
voltage. If this voltage is higher than 80V, the internal
First,selecttheinputdroppingresistor.Theresistorshould
allow 2mA of current with the supply at –36V.
(36V − 11.5V)
RIN ≤
= 12.25k
2mA
The nearest lower 5% value is 12k.
–48V_RTN
R
IN
TO
MODULE
INPUT
12k
0.5W
R3
33k
3
V
CC
LTC4354
FAULT
7
V
D1
LED
SS
DA
DB
GA
4
GB
1
8
6
2, 5
C
IN
R1
2k
R2
2k
1µF
V
V
A
B
4354 F02
M1
IRF3710S
M2
IRF3710S
Figure 2. –36V to –72V/5A Design Example
4354fc
8
LTC4354
applicaTions inForMaTion
The worst-case power dissipation in R :
The LED, D1, requires at least 1mA of current to fully turn
on, therefore R3 is set to 33k to accommodate lowest
input supply voltage of –36V.
IN
(72V − 10.5V)2
P =
= 0.315W
12k
Layout Considerations
Choose a 12k 0.5W resistor or use two 5.6k 0.25W resis-
tors in series.
The following advice should be considered when laying
out a printed circuit board for the LTC4354.
Next,choosetheN-channelMOSFET.The100V,IRF3710S
in DD-Pak package with R
= 23mΩ (max) offers a
The bypass capacitor provides AC current to the device
DS(ON)
good solution. The maximum voltage drop across it is:
so place it as close to the V and V pins as possible.
CC SS
The inputs to the servo amplifiers, DA, DB and V pins,
SS
∆V = (5A)(23mΩ) = 115mV
should be connected directly to the MOSFETs’ terminals
ThemaximumpowerdissipationintheMOSFETisamere:
P = (5A)(115mV) = 0.6W
using Kelvin connections for good accuracy.
Keep the traces to the MOSFETs wide and short. The PCB
tracesassociatedwiththepowerpaththroughtheMOSFETs
should have low resistance.
R1 and R2 are chosen to be 2k to protect DA and DB pins
frombeingdamagedbyhighvoltagespikesthatcanoccur
during an input supply fault.
Typical applicaTions
–5.2V Diode-Or Controller
Positive Low Voltage Diode-OR Combines
Multiple Switching Converters
GND
12V
470Ω
R3
2k
3
V
CC
V
CC
LOAD
LTC4354
FAULT
LTC4354
7
1µF
V
SS
V
GA,GB DA,DB
DA DB
GA
4
GB
EE
1
8
6
2, 5
D1
C
IN
1.2V
LED
1µF
100A
V
V
= –5.2V
= –5.2V
A
B
4354 TA02
INPUT
HAT2165 ×6
M1
Si4466DY
240Ω*
12V
M2
Si4466DY
470Ω
1.2V, 200A
OUTPUT BUS
V
CC
LTC4354
1µF
V
GA,GB DA,DB
EE
1.2V
100A
INPUT
4354 TA03
HAT2165 ×6
240Ω*
*OPTIONAL PRELOAD
4354fc
9
LTC4354
Typical applicaTions
–36V to –72V/20A High Current with Parallel FETs
–48V_RTN
RTN
R
IN1
10k
R3
30k
3
V
CC
LTC4354
FAULT
7
V
SS
DA
DB
GA
GB
1
R1
2k
8
R2
2k
4
6
2, 5
D1
LED
C
IN1
1µF
V
= –48V
–48V OUT
A
M1
IRF3710
M2
IRF3710
RTN
R
IN2
10k
R6
30k
3
V
CC
LTC4354
FAULT
7
V
SS
DA
DB
GA
GB
6
1
8
4
2, 5
D2
LED
R4
2k
R5
2k
C
IN2
1µF
V
= –48V
B
4354 TA04
M3
IRF3710
M4
IRF3710
–12V Diode-OR Controller
GND
R
IN
IN754
BV = 6.8V
2k
R3
10k
3
V
C
D
Z
CC
IN
1µF
LTC4354
LOAD
FAULT
7
V
SS
DA DB
GA
GB
1
8
4
6
2, 5
D1
LED
V
= –12V
= –12V
A
B
4354 TA05
M1
Si4862DY
V
M2
Si4862DY
4354fc
10
LTC4354
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DDB Package
8-Lead Plastic DFN (3mm × 2mm)
(Reference LTC DWG # 05-08-ꢀ702 Rev B)
0.6ꢀ 0.05
(2 SIDES)
0.70 0.05
2.55 0.05
ꢀ.ꢀ5 0.05
PACKAGE
OUTLINE
0.25 0.05
0.50 BSC
2.20 0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.ꢀꢀ5
0.40 0.ꢀ0
3.00 0.ꢀ0
(2 SIDES)
TYP
5
R = 0.05
TYP
8
2.00 0.ꢀ0
(2 SIDES)
PIN ꢀ BAR
TOP MARK
PIN ꢀ
R = 0.20 OR
0.25 × 45°
(SEE NOTE 6)
0.56 0.05
(2 SIDES)
CHAMFER
4
ꢀ
(DDB8) DFN 0905 REV B
0.25 0.05
0.75 0.05
0.200 REF
0.50 BSC
2.ꢀ5 0.05
(2 SIDES)
0 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
ꢀ. DRAWING CONFORMS TO VERSION (WECD-ꢀ) IN JEDEC PACKAGE OUTLINE M0-229
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.ꢀ5mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN ꢀ LOCATION ON THE TOP AND BOTTOM OF PACKAGE
4354fc
11
LTC4354
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
.045 ±.005
NOTE 3
.050 BSC
7
5
8
6
.245
MIN
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
3
4
2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
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12
LTC4354
revision hisTory (Revision history begins at Rev C)
REV
DATE
DESCRIPTION
PAGE NUMBER
C
04/12 Updated package/Order Information format
Changed Figure 2
2
8
Updated DDB package drawing
11
4354fc
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
13
LTC4354
Typical applicaTion
–48V Diode-OR Controller with Fuse Monitoring
–48V_RTN
12k
0.5W
33k
V
CC
LOAD
LTC4354
GA
FAULT
V
SS
DA DB
1k
GB
MMBD2836LT1
LED
1k
1k
1µF
MMBD2836LT1
V
V
= –48V
= –48V
A
B
4354 TA06
IRF540NS
1k
IRF540NS
relaTeD parTs
PART NUMBER
LT®1640AH/LT1640AL
LT4250
DESCRIPTION
COMMENTS
Negative High Voltage Hot Swap™ Controllers in SO-8 Negative High Voltage Supplies from –10V to –80V
–48V Hot Swap Controller
Active Current Limiting, Supplies from –20V to –80V
Fast Active Current Limiting, Supplies from –15V
LTC4251/LTC4251-1/
LTC4251-1
–48V Hot Swap Controllers in SOT-23
LTC4252-1/LTC4252-2/
LTC4252-1A/LTC4252-2A
–48V Hot Swap Controllers in MS8/MS10
–48V Hot Swap Controller with Sequencer
Fast Active Current Limiting, Supplies from –15V,
Drain Accelerated Response
LTC4253
Fast Active Current Limiting, Supplies from –15V,
Drain Accelerated Response, Sequenced Power Good Outputs
LT4351
MOSFET Diode-OR Controller
N-Channel MOSFET, 1.2V to 18V, Fast Switching for High Current
P-Channel MOSFET, 3V to 28V Range
LTC4412
Low Loss PowerPath™ Controller in ThinSOT™
4354fc
LT 0412 REV C • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
14
●
●
LINEAR TECHNOLOGY CORPORATION 2004
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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