LTC4235
Dual 12V Ideal Diode-OR
and Single Hot Swap Controller
with Current Monitor
Fea T Descrip T
TM
n
Ideal Diode-OR and Inrush Current Control for The LTC 4235 offers ideal diode-OR and Hot Swap
Redundant Supplies functions for two 12V power rails by controlling external
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N-channel MOSFETs. MOSFETs acting as ideal diodes
Low Loss Replacement for Power Schottky Diodes
n
replace two high power Schottky diodes and the associ-
Enables Safe Board Insertion into a Live Backplane
n ated heat sinks, saving power and board area. A Hot Swap
9V to 14V Operation
n control MOSFET allows a board to be safely inserted and
Current Monitor Output
n removed from a live backplane by limiting inrush current.
Controls N-Channel MOSFETs
The supply output is also protected against short-circuit
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Limits Peak Fault Current in 1s
faults with a foldback current limit and circuit breaker.
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Adjustable Current Limit with Foldback
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Adjustable Current Limit Fault Delay
The LTC4235 regulates the forward voltage drop across
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0.5s Ideal Diode Turn-On and Turn-Off Time
the MOSFETs to ensure smooth current transfer from one
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Smooth Switchover without Oscillation
supply to the other without oscillation. The ideal diodes
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Fault and Power Good Outputs
turn on quickly to reduce the load voltage droop during
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LTC4235-1: Latch Off After Fault
supply switchover. If the input supply fails or is shorted,
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LTC4235-2: Automatic Retry After Fault a fast turn-off minimizes reverse-current transients.
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20-Pin 4mm x 5mm QFN Package
A current sense amplifier translates the voltage across the
sense resistor to a ground referenced signal. The LTC4235
allows turn-on/off control, and reports fault and power
a T
good status for the supply.
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Redundant Power Supplies
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot
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High Availability Systems and Servers
Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of
their respective owners. Protected by U.S. Patents, including 7920013, 8022679.
n
Telecom and Network Infrastructure
Typical a T
Ideal Diode-OR with Hot Swap Application
Smooth Supply Switchover
SiR158DP
12V
IN2
0.1F
SiR158DP 0.003 SiR158DP
IN1
12V
12V
IN1
1V/DIV
7A
+
0.1F 0.1F
C
LOAD IN2
1V/DIV
I
IN1
+
13.7k
CPO1 IN1 DGATE1 CPO2 IN2 DGATE2 REG SENSE SENSE HGATE OUT
2A/DIV
ON
FAULT
I
2k IN2
2A/DIV
LTC4235
PWRGD
4235 TA01b
200ms/DIV
IMON ADC
EN
INTV
CC GND D2OFF FTMR
0.1F 0.1F 4235 TA01a
4235f
1
For more information www.linear.com/LTC4235
ion pplica
ions pplica
ion uresLTC4235
a T e Maxi Mu M r a T (Notes 1, 2)
Supply Voltages CPO1, CPO2 (Note 3) ............................. 0.3V to 35V
IN1, IN2 .................................................. 0.3V to 24V DGATE1, DGATE2 (Note 3) ..................... 0.3V to 35V
INTV ..................................................... 0.3V to 7V HGATE (Note 4) ..................................... 0.3V to 35V
CC
+ +
REG ...........................SENSE 5V to SENSE + 0.3V OUT ....................................................... 0.3V to 24V
Input Voltages Average Currents
ON, D2OFF, EN ...................................... 0.3V to 24V FAULT, PWRGD ....................................................5mA
FTMR .....................................0.3V to INTV + 0.3V INTV ...............................................................10mA
CC CC
+
SENSE , SENSE ................................... 0.3V to 24V Operating Ambient Temperature Range
Output Voltages LTC4235C ................................................ 0C to 70C
IMON ....................................................... 0.3V to 7V LTC4235I .............................................40C to 85C
FAULT, PWRGD ...................................... 0.3V to 24V Storage Temperature Range .................. 65C to 150C
p c F T
TOP VIEW
20 19 18 17
1 16 PWRGD
SENSE
+
SENSE 2 15 FAULT
IN1 3 14 ON
21
INTV 4 13 D2OFF
CC
GND 5 12 REG
6 11 IMON
IN2
7 8 9 10
UFD PACKAGE
20-LEAD (4mm 5mm) PLASTIC QFN
T = 125C, = 43C/W (NOTE 5)
JMAX JA
EXPOSED PAD (PIN 21) PCB GND CONNECTION OPTIONAL
o r D i n F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4235CUFD-1#PBF LTC4235CUFD-1#TRPBF 42351 20-Lead (4mm x 5mm) Plastic QFN 0C to 70C
LTC4235CUFD-2#PBF LTC4235CUFD-2#TRPBF 42352 20-Lead (4mm x 5mm) Plastic QFN 0C to 70C
LTC4235IUFD-1#PBF LTC4235IUFD-1#TRPBF 42351 20-Lead (4mm x 5mm) Plastic QFN 40C to 85C
LTC4235IUFD-2#PBF LTC4235IUFD-2#TRPBF 42352 20-Lead (4mm x 5mm) Plastic QFN 40C to 85C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: