LTC4222
Dual Hot Swap Controller
2
with I C Compatible
Monitoring
FEATURES
DESCRIPTION
The LTC®4222 Hot Swap™ controller allows two power
paths to be safely inserted and removed from a live back-
plane. Using external N-channel pass transistors, board
supply voltages and inrush currents are ramped up at an
adjustable rate. An I C interface and onboard ADC allows
for monitoring of current, voltage and fault status for
each channel.
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Allows Safe Insertion Into a Live Backplane
n
10-Bit ADC Monitors Currents and Voltages
2
n
I C/SMBus Interface
n
Wide Operating Voltage Range: 2.9V to 29V
2
n
dI/dt Controlled Soft-Start
n
High Side Drive for External N-Channel MOSFETs
n
No External Gate Capacitors Required
n
Input Overvoltage/Undervoltage Protection
The device features adjustable, analog, foldback current
limit circuits and a Soft-Start circuit that sets the dI/dt of
the inrush currents. An I C interface may configure the
part to latch off or automatically restart after the LTC4222
detects a fault on either channel.
n
Optional Latchoff or Auto-Retry After Faults
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Alert Host After Faults
Inrush Current Limit with Foldback
2
n
n
Available in 32-Pin (5mm × 5mm) QFN and 36-Pin
SSOP Packages
The controller has additional features to interrupt the host
when a fault has occurred, notify when output power is
good, detect insertion of a load card and power-up either
APPLICATIONS
2
n
Live Board Insertion
automatically upon insertion or wait for an I C command
n
Electronic Circuit Breakers
to turn on.
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Computers, Servers
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Hot Swap
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 7330065.
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Platform Management
TYPICAL APPLICATION
Advanced Mezzanine Card Application
6mΩ
Si7336ADP
12V
7.4A
12V
34k
10.2k
3.57k
10Ω
–
0.1μF
10Ω
1.02k
Start-Up Waveform with Sequencing
UV1
OV1
ON
SDA
SCL
V
SENSE1 GATE1 SOURCE1
DD1
3.4k
FB1
GPIO1
EN1
12PGOOD
V
ON
SDA
SCL
IN1/2
10V/DIV
ADIN1
CONTACT
BOUNCE
ALERT
ALERT
TIMER
CONFIG
ADR0
ADR1
ADR2
V
OUT2
1μF
10V/DIV
LTC4222
NC
SS
V
68nF
OUT1
10V/DIV
ADIN2
INTV
CC
0.1μF
EN2
GPIO
PGOOD
10V/DIV
GND
OV2
UV2
GPIO2
FB2
AUXPGOOD
3.4k
–
V
SENSE2 GATE2 SOURCE2
DD2
1.02k
4222 TA01b
3.57k
4.99k
50ms/DIV
10Ω
10nF
10Ω
0.1μF
3.3V
6.55k
3.3V
150mA
Si1046R
300mΩ
BACKPLANE PLUG-IN
CARD
4222 TA01a
4222f
1