Document
Features
n Power Path and Inrush Current Control for Redundant Supplies
n Low Loss Replacement for Power Schottky Diodes n Allows Safe Hot Swapping from a Live Backplane n 2.9V to 18V Operating Range n Controls N-Channel MOSFETs n Limits Peak Fault Current in ≤1µs n 0.5µs Ideal Diode Turn-On and Reverse Turn-Off Time n Adjustable Current Limit with Circuit Breaker n Smooth Switchover without Oscillation n Adjustable Current Limit Fault Delay n Fault and Power Status Output n 20-Lead 4mm × 5mm QFN and 16-Lead SSOP Packages
Applications
n Redundant Power Supplies and Supply Holdup n Computer Systems and Servers n Telecom Networks
L, LT, LTC, LTM, Linear Technology and the Linear logo 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.
LTC4227
Dual Ideal Diode and Single Hot Swap Controller
Description
The LTC®4227 offers ideal diode-OR and Hot Swap™ functions for two power rails by controlling external Nchannel MOSFETs. MOSFETs acting as ideal diodes replace two high power Schottky diodes and the associated heat sinks, saving power and board area. A Hot Swap control MOSFET allows a board to be safely inserted and removed from a live backplane by limiting inrush current. The supply output is also protected against short-circuit faults with a fast acting current limit and internal timed circuit breaker. The LTC4227 regulates the forward voltage drop across the MOSFETs to ensure smooth current transfer from one supply to the other without oscillation. The ideal diodes turn on quickly to reduce the load voltage droop during supply switchover. If the input supply fails or is shorted, a fast turn-off minimizes reverse-current transients. The LTC4227 allows turn-on/off control, and reports fault and power good status for the supply.
PART LTC4227-1 LTC4227-2 LTC4227-3 LTC4227-4
OVERCURRENT FAULT LATCH OFF RETRY LATCH OFF RETRY
START-UP DELAY 100ms 100ms 1.6ms 1.6ms
Typical Application
Diode-OR with Hot Swap Application
SiR462DP 12V
0.1µF 12V
SiR462DP 0.006Ω Si7336ADP
+
12V 7.6A
0.1µF
100µF
137k CPO1 IN1 DGATE1 CPO2 ON
20k
IN2 DGATE2 SENSE+ SENSE– HGATE OUT
LTC4227
FAULT PWRGD
BACKPLANE CARD CONNECTOR CONNECTOR
EN INTVCC 0.1µF
D2ON
GND
TMR 0.1µF
4227 TA01a
For more information www.linear.com/LTC4227
IN1 1V/DIV
IN2 1V/DIV
IIN1 2A/DIV
IIN2 2A/DIV
Smooth Supply Switchover
200ns/DIV
4227 TA01b
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1
LTC4227
Absolute Maximum Ratings (Notes 1, 2)
Supply Voltages
IN1, IN2................................................... –0.3V to 24V
INTVCC...................................................... –0.3V to 7V Input Voltages
ON, EN, D2ON ........................................ –0.3V to 24V
STMENRS...E.+..,..S..E..N...S..E..–..........................................–..0....3..V...t.o...I.N–T0V.3CVC
+ 0.3V to 24V
Output Voltages
FAULT, PWRGD....................................... –0.3V to 24V
CPO1, CPO2 (Note 3).............................. –0.3V to 35V
DGATE1, DGATE2 (Note 3)...................... –0.3V to 35V
HGATE (Note 4)...................................... –0.3V to 35V OUT........................................................ –0.3V to 24V Average Currents FAULT, PWRGD.....................................................5mA INTVCC..................................................................1mA Operating Temperature Range LTC4227C................................................. 0°C to 70°C LTC4227I..............................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) GN Package....................................................... 300°C
Pin Configuration
TOP VIEW
DGATE1 CPO1 HGATE OUT
SENSE– 1 SENSE+ 2
IN1 3 INTVCC 4
GND 5
IN2 6
20 19 18 17
16 NC
15 ON
21
14 EN 13 TMR
12 D2ON
11 FAULT
7 8 9 10
DGATE2 CPO2 NC
PWRGD
UFD PACKAGE 20-LEAD (4mm × 5mm) PLASTIC QFN
TJMAX = 125°C, θJA = 34°C/W EXPOSED PAD (PIN 21) PCB GND CONNECTION OPTIONAL
TOP VIEW
DGATE1 SENSE– SENSE+
IN1
INTVCC GND
IN2
DGATE2
1 2 3 4 5 6 7 8
16 CPO1 15 HGATE 14 OUT 13 ON 12 TMR 11 D2ON 10 PWRGD 9 CPO2
GN PACKAGE 16-LEAD PLASTIC SSOP NARROW
TJMAX = 125°C, θJA = 110°C/W
2
For more information www.linear.com/LTC4227
422712fa
LTC4227
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4227CUFD-1#PBF
LTC4227CUFD-1#TRPBF 42271
20-Lead (4mm × 5mm) Plastic QFN
0°C to 70°C
LTC4227CUFD-2#PBF
LTC4227CUFD-2#TRPBF 42272
20-Lead (4mm × 5mm) Plastic QFN
0°C to 70°C
LTC4227CUFD-3#PBF
LTC4227CUFD-3#TRPBF 42273
20-Lead (4mm × 5mm) Plastic QFN
0°C to 70°C
LTC4227CUFD-4#PBF
LTC4227CUFD-4#TRPBF 42274
20-Lead (4mm × 5mm) Plastic QFN
0°C to 70°C
LTC4227IUFD-1#PBF
LTC4227IUFD-1#TRPBF 42271
20-Lead (4mm × 5mm) Plastic QFN
–40°C to 85°C
LTC4227IUFD-2#PBF
LTC4227IUFD-2#TRP.