LTC4354CS8#PBF - LINEAR TECHNOLOGY

LTC4354

4354fc

Typical applicaTion

FeaTures DescripTion

Negative Voltage

Diode-OR Controller

and Monitor

The LT C

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.

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.

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.

A fault detection circuit with an open-drain output capable

of driving an LED or opto-coupler indicates either MOSFET

short, MOSFET open or supply failed.

–48V Diode-OR Power Dissipation vs Load Current

applicaTions

n Controls N-Channel MOSFETs

n Replaces Power Schottky Diodes

n Less Than 1µs Turn-off Time Limits Peak

Fault Current

n 80V Operation

n Smooth Switchover without Oscillation

n No Reverse DC Current

n Fault Output

n Selectable Fault Thresholds

n Available in 8-Lead (3mm × 2mm) DFN and

8-Lead SO Packages

n AdvancedTCA

Systems

n –48V Distributed Power Systems

n Computer Systems/Servers

n Telecom Infrastructure

n Optical Networks

L, LT , LT C , LT M , 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.

LTC4354 LOAD

DB GADA GB VSS

VB = –48V

VA = –48V

–48V_RTN

FAULT

IRF3710

IRF3710 4354 TA01

VCC

33k

12k

2k2k

LED

1µF

CURRENT (A)

POWER DISSIPATION (W)

24 6

4354 TA01b

8 10

DIODE (MBR10100)

FET (IRF3710)

POWER

SAVED

LTC4354

4354fc

Lead Free Finish

TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC4354CDDB#TRMPBF LTC4354CDDB#TRPBF LBBK 8-Lead (3mm × 2mm) Plastic DFN 0°C to 70°C

LTC4354IDDB#TRMPBF LTC4354IDDB#TRPBF LBMB 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C

TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.

absoluTe MaxiMuM raTings

ICC (100µs duration) ...............................................50mA

Output Voltages

GA, GB .........................................–0.3V to VCC + 0.3V

FAULT ...................................................... –0.3V to 7V

Input Voltages

DA, DB ................................................... –0.3V to 80V

Input Current

DA, DB Current ................................... –1mA to 20mA

(Note 1)

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC4354CS8#PBF LTC4354CS8#TRPBF 4354 8-Lead Plastic SO 0°C to 70°C

LTC4354IS8#PBF LTC4354IS8#TRPBF 4354I 8-Lead Plastic SO –40°C to 85°C

Consult LT C Marketing for parts specified with wider operating temperature ranges.

Consult LT C 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/

TOP VIEW

DDB PACKAGE

8-LEAD (3mm × 2mm) PLASTIC DFN

1DA

VSS

VCC

FAULT

VSS

TJMAX = 125°C, θJA = 76°C/W

EXPOSED PAD (PIN 9) IS VSS, CONNECTION TO PCB OPTIONAL

TOP VIEW

FAULT

VSS

VCC

S8 PACKAGE

8-LEAD PLASTIC SO

TJMAX = 125°C, θJA = 150°C/W

Operating Temperature Range

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

pin conFiguraTion

LTC4354

4354fc

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.

elecTrical characTerisTics

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: ICC is defined as the current level where the VCC voltage is lower

by 100mV from the value with 2mA of current.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VZInternal Shunt Regulator Voltage ICC = 5mA l10.25 11 11.75 V

∆VZInternal Shunt Regulator Load Regulation ICC = 2mA to 10mA 200 300 mV

VCC Operating Voltage Range l4.5 VZV

ICC VCC Supply Current VCC = (VZ – 0.1V), Note 2

VCC = 5V

0.5

1.2

0.8

1.1

VGATE GATE Pins Output High Voltage VCC = 10.25V

VCC = 5V

4.75

10.25 V

IGATE GATE Pins Pull-Up Current VSD = 60mV; VGATE = 5.5V

VSD = 0V; VGATE = 5.5V

–15

–30

–60

µA

∆VSD Source Drain Sense Threshold Voltage (VSS – VDX)l10 30 55 mV

∆VSD(F LT )Source Drain Fault Detection Threshold (VSS – VDX); VCC = 7V to VZl200 260 320 mV

tOFF Gate Turn-Off Time in Fault Condition CGATE = 3300pF; VGATE ≤ 2V; VSD = –0.4V 0.7 1.2 µs

VFAULT FAULT Pin Output Low IFAULT = 5mA l200 400 mV

IFAULT FAULT Pin Leakage Current VFAULT = 5V l±1 µA

IDDrain Pin Input Current VDX = 0V

VDX = 80V

–3.5

1.1

–2.5

1.5

–1.5

1.9

µA

Note 3: An internal shunt regulator limits the VCC pin to less than 12V

above VSS. Driving this pin to voltages beyond the clamp may damage

the part.

Note 4: All currents into pins are positive; all voltages are referenced to

VSS unless otherwise specified.

LTC4354

4354fc

Specifications are at TA = 25°C, ICC = 5mA, VSS = 0V,

unless otherwise noted.

Typical perForMance characTerisTics

Source Drain Sense Voltage

vs Temperature IGATE(UP) vs ∆VSD Gate Turn-Off Time vs Temperature

Fault Threshold Voltage

vs Temperature Drain Pin Current vs Temperature Drain Pin Current vs Voltage

Shunt Regulator Voltage

vs Input Current

Shunt Regulator Voltage

vs Input Current at Temperature

Source Drain Sense Voltage

vs Supply Voltage

ICC (mA)

VZ (V)

11.0

4354 G01

10.0

11.5

10.5

515

12.0

TEMPERATURE (°C)

–50

VZ (V)

11.4

11.0

10.6

11.2

10.8

–25 0 25

4354 G02

50 75 100 125

ICC = 10mA

ICC = 5mA

ICC = 2mA

VCC (V)

∆VSD (mV)

7 9 11 12

4354 G03

6 8 10

TEMPERATURE (°C)

–50

VSD (mV)

–25 0 25

4354 G04

50 75 100 125

∆VSD (mV)

IGATE(UP) (µA)

100

40 50 60

4354 G05

70 80 90

TEMPERATURE (°C)

–50

tOFF (ns)

740

700

660

720

680

–25 0 25

4354 G05

50 75 100 125

TEMPERATURE (°C)

–50

∆VSD(FLT) (mV)

290

250

210

270

230

–25 0 25

4354 G06

50 75 100 125

TEMPERATURE (°C)

–50

ID (µA)

–3.2

–2.8

–2.4

–3.0

–2.6

–25 0 25

4354 G08

50 75 100 125

VDX = 0V

VDX (V)

0.3

ID (mA)

–1

–0.5

–0.75

–0.25

0.4 0.5 0.6

4354 G09

0.7 0.8 0.9 1

90°C

25°C

–45°C

LTC4354

4354fc

pin FuncTions

DA, DB (Pins 1, 8): Drain Voltage Sense Inputs. These

pins sense source drain voltage drop across the N-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

VSS if unused.

VCC (Pin 3): Positive Supply Voltage Input. Connect this

pin to the positive side of the supply through a resistor.

An internal shunt regulator that can sink up to 20mA

typically clamps VCC at 11V. Bypass this pin with a 1µF

capacitor to VSS.

GA, GB (Pins 4, 6): Gate Drive Outputs. Gate pins pull high

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

across the MOSFET. If reverse current develops more than

–140mV of voltage drop across the MOSFET, the pins pull

low to VSS in less than 1µs. Quickly turning off the pass

transistors prevents excessive reverse currents. Leave the

pins open if unused.

VSS (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.

FAULT (Pin 7): Fault Output. Open-drain output that

normally pulls the FAULT pin to VSS and shunts current

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

transistors have failed open or failed short creating a cross

conduction current in between the two power supplies.

Connect to VSS if unused.

EXPOSED PAD (Pin 9): Exposed pad is common to VSS

and may be left open or connected to Pins 2 and 5.

FuncTional DiagraM

30mV

BV = 11V

30mV

VSS

VCC

VSS

55k

4354 FD

VSS

FAULT

–

FAULT DETECTION

AMP B

AMP A

VSS

55k

LTC4354

4354fc

TiMing DiagraM

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.

The LTC4354 is a negative voltage diode-OR controller that

drives two external N-channel MOSFETs as pass transis-

tors to replace ORing diodes. The MOSFETs are connected

together at the source pins. The common source node is

connected to the VSS pin which is the negative supply of

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.

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

4354 TD01

VSS – VDX

VGATE

tOFF

100mV

–400mV

operaTion

gate is driven fully on and the voltage drop is equal to the

RDS(ON) • ILOAD.

When the power supply voltages are nearly equal, this

regulation technique ensures that the load current is

smoothly shared between them without oscillation. The

current level flowing through each pass transistor depends

on the RDS(ON) of the MOSFET and the output impedance

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.

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.

The LTC4354 is powered from system ground through a

current limiting resistor. An internal shunt regulator that

can sink up to 20mA clamps the VCC pin to 11V above VSS.

A 1µF bypass capacitor across VCC and VSS pins filters

supply transients and supplies AC current to the device.

LTC4354

4354fc

Input Power Supply

The power supply for the device is derived from –48_RTN

through an external current limiting resistor (RIN). An

internal shunt regulator clamps the voltage at VCC pin to

11V. A 1µF decoupling capacitor to VSS is recommended.

It also provides a soft-start to the part.

RIN should be chosen to accommodate the maximum

supply current requirement of 2mA at the expected input

operating voltage.

RIN ≤

IN(MIN)

−V

Z(MAX)

)

ICC(MAX)

The power dissipation of the resistor is calculated at the

maximum DC input voltage:

P=(V

IN(MAX) −VCC(MIN))2

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.

MOSFET SELECTION

The LTC4354 drives N-channel MOSFETs to conduct the

load current. The important features of the MOSFETs are

on-resistance RDS(ON), the maximum drain-source voltage

VDSS, and the threshold voltage.

The gate drive for the MOSFET is guaranteed to be more

than 10V and less than 12V. This allows the use of standard

threshold voltage N-channel MOSFETs. An external zener

diode can be used to clamp the potential at the VCC pin

to as low as 4.5V if the gate to source rated breakdown

voltage is less than 12V.

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.

applicaTions inForMaTion

Figure 1. Method of Protecting the DA and DB Pins from

Negative Inputs. One Channel Shown

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

RDS(ON) should be small enough to conduct the maximum

load current while not triggering a fault, and to stay within

the MOSFET’s power rating at the maximum load current

(I2 • RDS(ON)).

Fault Conditions

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, the internal pull-down at the FAULT pin turns off

and allows the current to flow through the LED or opto-

coupler. Conditions that cause high voltage across the pass

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.

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.

4354 F01

DA GA

LTC4354

VSS

MMBD2836LT1

LTC4354

4354fc

LTC4354

MODULE

INPUT

DB GADA GB VSS

–48V_RTN

FAULT

IRF3710S

4354 F02

VCC

33k

RIN

12k

0.5W

LED

1 8 4

6 2, 5

CIN

1µF

applicaTions inForMaTion

System Power Supply Failure

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

and source pins of the pass transistor, the LTC4354 drives

the gate low fast and turns it off.

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

turns on the N-channel MOSFET to reduce the voltage drop

across it, a process that takes less than 1ms depending

on the gate charge of the MOSFET.

Drain Resistor

Tw o 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

discharge the output capacitor. This current stores energy

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

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.

Loop Stability

The servo loop is compensated by the parasitic capacitance

of the power N-channel MOSFET. No further compensation

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.

Design Example

The following demonstrates the calculations involved for

selecting components in a –36V to –72V system with 5A

maximum load current, see Figure 2.

First, select the input dropping resistor. The resistor should

allow 2mA of current with the supply at –36V.

RIN ≤(36V −11.5V)

2mA

=12.25k

The nearest lower 5% value is 12k.

Figure 2. –36V to –72V/5A Design Example

LTC4354

4354fc

applicaTions inForMaTion

Typical applicaTions

–5.2V Diode-Or Controller Positive Low Voltage Diode-OR Combines

Multiple Switching Converters

The worst-case power dissipation in RIN:

P=(72V −10.5V)2

12k

=0.315W

Choose a 12k 0.5W resistor or use two 5.6k 0.25W resis-

tors in series.

Next, choose the N-channel MOSFET. The 100V, IRF3710S

in DD-Pak package with RDS(ON) = 23mΩ (max) offers a

good solution. The maximum voltage drop across it is:

∆V = (5A)(23mΩ) = 115mV

The maximum power dissipation in the MOSFET is a mere:

P = (5A)(115mV) = 0.6W

R1 and R2 are chosen to be 2k to protect DA and DB pins

from being damaged by high voltage spikes that can occur

during an input supply fault.

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.

Layout Considerations

The following advice should be considered when laying

out a printed circuit board for the LTC4354.

The bypass capacitor provides AC current to the device

so place it as close to the VCC and VSS pins as possible.

The inputs to the servo amplifiers, DA, DB and VSS pins,

should be connected directly to the MOSFETs’ terminals

using Kelvin connections for good accuracy.

Keep the traces to the MOSFETs wide and short. The PCB

traces associated with the power path through the MOSFETs

should have low resistance.

LTC4354 LOAD

DB GADA GB VSS

VB = –5.2V

VA = –5.2V

GND

FAULT

Si4466DY

4354 TA02

VCC

LED

CIN

1µF

2, 561 48

12V

470Ω

240Ω*

1.2V, 200A

OUTPUT BUS

4354 TA03

*OPTIONAL PRELOAD

HAT2165 ×6

1.2V

100A

INPUT

1µF

VEE GA,GB

VCC

LTC4354

DA,DB

12V

470Ω

240Ω*

1.2V

100A

INPUT

1µF

VEE GA,GB

VCC

LTC4354

DA,DB

LTC4354

4354fc

–36V to –72V/20A High Current with Parallel FETs

–12V Diode-OR Controller

Typical applicaTions

LTC4354

DB GADA GB VSS

VB = –48V

FAULT

IRF3710

4354 TA04

VCC

30k

RIN2

10k

LED

CIN2

1µF

LTC4354

DB GADA GB VSS

VA = –48V –48V OUT

–48V_RTN RTN

RTN

FAULT

IRF3710

VCC

30k

RIN1

10k

LED

CIN1

1µF

2, 561 48

LTC4354 LOAD

DB GADA GB VSS

2, 561 48

VB = –12V

VA = –12V

GND

FAULT

Si4862DY

4354 TA05

VCC

10k

RIN

2k IN754

BV = 6.8V

CIN

1µF

LED

LTC4354

4354fc

package DescripTion

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

2.00 ±0.10

(2 SIDES)

NOTE:

1. DRAWING CONFORMS TO VERSION (WECD-1) 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 0.15mm 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

0.40 ±0.10

BOTTOM VIEW—EXPOSED PAD

0.56 ±0.05

(2 SIDES)

0.75 ±0.05

R = 0.115

TYP

R = 0.05

TYP

2.15 ±0.05

(2 SIDES)

3.00 ±0.10

(2 SIDES)

PIN 1 BAR

TOP MARK

(SEE NOTE 6)

0.200 REF

0 – 0.05

(DDB8) DFN 0905 REV B

0.25 ±0.05

0.50 BSC

PIN 1

R = 0.20 OR

0.25 × 45°

CHAMFER

0.25 ±0.05

2.20 ±0.05

(2 SIDES)

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

0.61 ±0.05

(2 SIDES)

1.15 ±0.05

0.70 ±0.05

2.55 ±0.05

PACKAGE

OUTLINE

0.50 BSC

DDB Package

8-Lead Plastic DFN (3mm × 2mm)

(Reference LTC DWG # 05-08-1702 Rev B)

LTC4354

4354fc

package DescripTion

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

.016 – .050

(0.406 – 1.270)

.010 – .020

(0.254 – 0.508)× 45°

0°– 8° TYP

.008 – .010

(0.203 – 0.254)

SO8 0303

.053 – .069

(1.346 – 1.752)

.014 – .019

(0.355 – 0.483)

TYP

.004 – .010

(0.101 – 0.254)

.050

(1.270)

BSC

1234

.150 – .157

(3.810 – 3.988)

NOTE 3

8765

.189 – .197

(4.801 – 5.004)

NOTE 3

.228 – .244

(5.791 – 6.197)

.245

MIN .160 ±.005

RECOMMENDED SOLDER PAD LAYOUT

.045 ±.005

.050 BSC

.030 ±.005

TYP

INCHES

(MILLIMETERS)

NOTE:

1. DIMENSIONS IN

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)

S8 Package

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

LTC4354

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.

revision hisTory

REV DATE DESCRIPTION PAGE NUMBER

C 04/12 Updated package/Order Information format 2

Changed Figure 2 8

Updated DDB package drawing 11

(Revision history begins at Rev C)

LTC4354

4354fc

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

 LINEAR TECHNOLOGY CORPORATION 2004

LT 0412 REV C • PRINTED IN USA

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LTC4253 –48V Hot Swap Controller with Sequencer 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

LTC4412 Low Loss PowerPath™ Controller in ThinSOT™ P-Channel MOSFET, 3V to 28V Range

LTC4354 LOAD

DB GADA GB VSS

VB = –48V

VA = –48V

–48V_RTN

FAULT

IRF540NS

IRF540NS 4354 TA06

VCC

33k

12k

0.5W

LED

1µF

MMBD2836LT1

–48V Diode-OR Controller with Fuse Monitoring