Kilowatt Hot Swap/Circuit Breaker with Telemetry
Parallel MOSFETs Share SOA
VOUT
100A
VIN
2.9V to 33V
LTC4282
EEPROM
I2C/SMBus
POWER
MULTIPLIER &
ENERGY
ACCUMULATOR
ILOAD
DUAL
12-/16-BIT
ADC
VIN /VOUT
GPIO
Parallel Current Paths Ease MOSFET SOA Requirements for High Current Boards
The LTC®4282 Hot SwapTM controller eases design of high power hot-pluggable boards by controlling two current-limited paths,
halving the safe operating area (SOA) requirement for each path’s MOSFET. Further SOA savings are afforded with a staged start
configuration employing a low SOA MOSFET in one path and low RDS(ON) MOSFETs in the other path. An integrated analog-todigital converter (ADC) reports board voltage, current, power and energy consumption through an I2C/SMBus digital interface. The
internal EEPROM provides nonvolatile storage for register configuration and fault log data, speeding development and debug.
Board Staged-Start Waveforms
Features
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Enables Safe Board Insertion into Live Backplane
I2C/SMBus Interface to Read Board Voltage, Current,
Power and Energy Usage
Internal EEPROM for Storing Configuration and Fault Log
12-/16-Bit ADC with < 0.7% Total Unadjusted Error
Wide Operating Voltage Range: 2.9V to 33V
High Current Application Features
nn Dual MOSFET Gate Drive and Current Sensing
nn 12V Gate Drive for Lower MOSFET R
DS(ON)
nn MOSFET Power Limiting with Current Foldback
Digital Features
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∆VGATE1
10V/DIV
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Programmable Current Limit and UV/OV/PG Thresholds
Stores Minimum and Maximum Measurements
nn Alerts When Programmed Thresholds Are Exceeded
nn Three General Purpose Inputs/Outputs
Continuously Monitors MOSFET Health
32-Pin (5mm × 5mm) QFN Package
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INRUSH FET
TURN-ON
∆VGATE2
VOUT
50A/DIV
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L, LT, LTC, LTM, Linear Technology and the Linear logo are
registered trademarks and Hot Swap is a trademark of Linear
Technology Corporation. All other trademarks are the property of
their respective owners.
IINRUSH
5ms/DIV
BYPASS FET
TURN-ON
LTC4282 Current Path Configurations
Matched Paths Share SOA
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Recommended for Above 50A Applications
MOSFETs Selected for High SOA and
Low RDS(ON)
Current Sharing Reduces MOSFET SOA
Requirements by Half
Long Fault Timer Rides Through Transients
0.5mΩ
VIN
Q2
0.5mΩ
SENSE2+
VDD
+
Q1
SENSE1+ SENSE1–
VOUT
CL
SENSE2– GATE1 GATE2 SOURCE
LTC4282
TIMER
GND
0.18µF
High Stress Staged Start Rides Through Transients
Q2 BYPASS
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Recommended for Below 50A Applications
Medium RDS(ON), High SOA Q1 Handles
Inrush, Load Surges and VIN Steps
Low RDS(ON) Q2 Bypasses Q1 In Normal
Operation
Long Fault Timer Rides Through Transients
0.5mΩ
VIN
+
Q1 STRESS
4.8k
VDD SENSE1/2+
ADC+
100Ω
1Ω
SENSE1– ADC –
VOUT
CL
SENSE2– GATE1 GATE2 SOURCE
24k
FET Stress
Signal Keeps
Q2 Off
GPIO2
LTC4282
TIMER
GND
0.18µF
11ms
Low Stress Staged Start for Lowest Cost
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Recommended for Above 50A Applications
Small, Economical Q1 Trickle Charges Load
Capacitance
Low RDS(ON) Q2 Bypasses Q1 When GPIO1
Signals Power Good
Short Fault Timer Disconnects on Overcurrent
0.5mΩ
Q2 BYPASS
VIN
10mΩ
Q1 TRICKLE
+
100Ω
VOUT
CL
30k
3.3µF
VDD
SENSE2+
SENSE1+ SENSE1–
SENSE2–
GATE1
GPIO1
LTC4282
TIMER
GATE2 SOURCE
24k
Gate RC
Sets Inrush
Output Low
Signal Keeps
Q2 Off
GND
4.7nF
300µs
www.linear.com/4282 n 1-800-4-LINEAR
0815