Document
Features
nn Ideal Diode-OR and Inrush Current Control for Redundant Supplies
nn Low Loss Replacement for Power Schottky Diodes nn Enables Safe Board Insertion into a Live Backplane nn 2.9V to 18V Operating Range nn Current Monitor Output nn Controls N-Channel MOSFETs nn Limits Peak Fault Current in ≤ 1µs nn Adjustable Current Limit with Foldback nn Adjustable Start-Up and Current Limit Fault Delay nn 0.5µs Ideal Diode Turn-On and Turn-Off Time nn Smooth Switchover without Oscillation nn Fault, Power Good and Diode Status Outputs nn LTC4236-1: Latch Off After Fault nn LTC4236-2: Automatic Retry After Fault nn 28-Pin 4mm x 5mm QFN Package
Applications
nn Redundant Power Supplies nn High Availability Systems and Servers nn Telecom and Network Infrastructure
LTC4236
Dual Ideal Diode-OR and Single Hot Swap Controller
with Current Monitor
Description
The LTC®4236 offers ideal diode-OR and Hot Swap functions for two power rails by controlling external N-channel 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 foldback current limit and electronic circuit breaker.
The LTC4236 regulates the forward voltage drop across the ideal diode MOSFETs to ensure smooth current transfer from one supply to the other without oscillation. The ideal diode MOSFETs 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.
A current sense amplifier translates the voltage across the sense resistor to a ground referenced signal. The LTC4236 provides adjustable start-up delay, turn-on/-off control, and reports fault and power good status for the supply.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7920013, 8022679.
Typical Application
12V
0.1µF 12V
Ideal Diode-OR with Hot Swap Application
SiR158DP
0.1µF
SiR158DP
0.1µF
0.003Ω SiR158DP
13.7k CPO1 IN1 DGATE1 CPO2 D2SRC IN2 DGATE2 REG SENSE+ CS+ SENSE– HGATE OUT
ON
FB
2k
EN
INTVCC
GND
0.1µF
LTC4236 D2OFF
DTMR 0.1µF
FAULT PWRGD DSTAT1 DSTAT2
FTMR
IMON
0.1µF
+
12V
IN1
7A 1V/DIV
CLOAD
IN2
1V/DIV
15k
IIN1
2A/DIV
2k
IIN2 2A/DIV
ADC
4236 TA01a
For more information www.linear.com/LTC4236
Smooth Supply Switchover
IN2 IN1
200ms/DIV
4236 TA01b
4236f
1
LTC4236
Absolute Maximum Ratings
(Notes 1, 2)
Supply Voltages IN1, IN2................................................... –0.3V to 24V INTVCC...................................................... –0.3V to 7V REG............................SENSE+ – 5V to SENSE+ + 0.3V
Input Voltages ON, D2OFF, EN ....................................... –0.3V to 24V FTMR, DTMR..........................–0.3V to INTVCC + 0.3V FB............................................................. –0.3V to 7V SENSE+, SENSE–, CS+, D2SRC............... –0.3V to 24V
Output Voltages IMON........................................................ –0.3V to 7V FAULT, PWRGD, DSTAT1, DSTAT2............ –0.3V to 24V CPO1, CPO2 (Notes 3, 4)........................ –0.3V to 35V DGATE1, DGATE2 (Notes 3, 4)................ –0.3V to 35V HGATE (Note 5)...................................... –0.3V to 35V OUT........................................................ –0.3V to 24V
Average Currents FAULT, PWRGD, DSTAT1, DSTAT2..........................5mA INTVCC................................................................10mA
Operating Ambient Temperature Range LTC4236C................................................. 0°C to 70°C LTC4236I..............................................–40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Pin Configuration
TOP VIEW
DGATE1 CPO1 HGATE OUT FB PWRGD
28 27 26 25 24 23
SENSE– 1
22 FAULT
SENSE+ 2
21 DSTAT1
CS+ 3
20 DSTAT2
IN1 4 INTVCC 5
GND 6
29
19 ON
18 D2OFF
17 NC
IN2 7
16 NC
D2SRC 8
15 REG
9 10 11 12 13 14
DGATE2 CPO2 DTMR FTMR EN IMON
UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN
TJMAX = 125°C, θJA = 43°C/W (NOTE 6) EXPOSED PAD (PIN 29) PCB GND CONNECTION OPTIONAL
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4236CUFD-1#PBF
LTC4236CUFD-1#TRPBF 42361
28-Lead (4mm x 5mm) Plastic QFN
0°C to 70°C
LTC4236CUFD-2#PBF
LTC4236CUFD-2#TRPBF 42362
28-Lead (4mm x 5mm) Plastic QFN
0°C to 70°C
LTC4236IUFD-1#PBF
LTC4236IUFD-1#TRPBF 42361
28-Lead (4mm x 5mm) Plastic QFN
–40°C to 85°C
LTC4236IUFD-2#PBF
LTC4236IUFD-2#TRPBF 42362
28-Lead (4mm x 5mm) Plastic QFN
–40°C to 85°C
Consult.