FeaTures
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LTC4236
Dual Ideal Diode-OR and
Single Hot Swap Controller
with Current Monitor
DescripTion
The
LTC
®
4236
offers ideal diode-OR and Hot Swap func-
tions 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.
Ideal Diode-OR and Inrush Current Control for
Redundant Supplies
Low Loss Replacement for Power Schottky Diodes
Enables Safe Board Insertion into a Live Backplane
2.9V to 18V Operating Range
Current Monitor Output
Controls N-Channel MOSFETs
Limits Peak Fault Current in ≤ 1µs
Adjustable Current Limit with Foldback
Adjustable Start-Up and Current Limit Fault Delay
0.5µs Ideal Diode Turn-On and Turn-Off Time
Smooth Switchover without Oscillation
Fault, Power Good and Diode Status Outputs
LTC4236-1: Latch Off After Fault
LTC4236-2: Automatic Retry After Fault
28-Pin 4mm x 5mm QFN Package
applicaTions
n
n
n
Redundant Power Supplies
High Availability Systems and Servers
Telecom and Network Infrastructure
Typical applicaTion
Ideal Diode-OR with Hot Swap Application
12V
0.1µF
12V
0.1µF
13.7k CPO1 IN1 DGATE1 CPO2
ON
2k
LTC4236
EN
INTV
CC
0.1µF
GND
D2OFF
DTMR
0.1µF
FTMR
0.1µF
4236 TA01a
Smooth Supply Switchover
SiR158DP
SiR158DP
SiR158DP
0.1µF
REG
SENSE
+
CS
+
SENSE
–
HGATE OUT
FB
2k
0.003
IN2
+
15k
12V
7A
C
LOAD
IN1
1V/DIV
IN2
1V/DIV
I
IN1
2A/DIV
I
IN2
2A/DIV
200ms/DIV
4236 TA01b
IN1
D2SRC IN2 DGATE2
FAULT
PWRGD
DSTAT1
DSTAT2
IMON
ADC
For more information
www.linear.com/LTC4236
1
4236f
LTC4236
absoluTe MaxiMuM raTings
(Notes 1, 2)
pin conFiguraTion
TOP VIEW
DGATE1
PWRGD
22
FAULT
21
DSTAT1
20
DSTAT2
29
19 ON
18 D2OFF
17 NC
16 NC
15 REG
9 10 11 12 13 14
DTMR
FTMR
EN
DGATE2
IMON
CPO2
HGATE
CPO1
OUT
Supply Voltages
IN1, IN2.................................................. –0.3V to 24V
INTV
CC
..................................................... –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 INTV
CC
+ 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
INTV
CC
...............................................................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
SENSE– 1
SENSE+ 2
CS+ 3
IN1 4
INTV
CC
5
GND 6
IN2 7
D2SRC 8
28 27 26 25 24 23
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W (NOTE 6)
EXPOSED PAD (PIN 29) PCB GND CONNECTION OPTIONAL
orDer inForMaTion
LEAD FREE FINISH
LTC4236CUFD-1#PBF
LTC4236CUFD-2#PBF
LTC4236IUFD-1#PBF
LTC4236IUFD-2#PBF
TAPE AND REEL
LTC4236CUFD-1#TRPBF
LTC4236CUFD-2#TRPBF
LTC4236IUFD-1#TRPBF
LTC4236IUFD-2#TRPBF
PART MARKING
42361
42362
42361
42362
PACKAGE DESCRIPTION
28-Lead (4mm x 5mm) Plastic QFN
28-Lead (4mm x 5mm) Plastic QFN
28-Lead (4mm x 5mm) Plastic QFN
28-Lead (4mm x 5mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°C
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
FB
2
4236f
For more information
www.linear.com/LTC4236
LTC4236
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted.
SYMBOL
Supplies
V
IN
I
IN
V
INTVCC
V
INTVCC(UVL)
Input Supply Range
Input Supply Current
Internal Regulator Voltage
Internal V
CC
Undervoltage Lockout
I = 0, –500µA
INTV
CC
Rising
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elecTrical characTerisTics
PARAMETER
CONDITIONS
MIN
2.9
TYP
MAX
18
UNITS
V
mA
V
V
mV
mV
V
V
V
µA
µA
µA
A
A
2.7
4.5
2.1
30
2
5
10
0.3
5
2.2
60
15
7
12
0.7
–90
–60
–50
–100
–90
–1.5
1.5
4
5.5
2.3
90
28
14
14
1.1
–130
–130
–120
∆V
INTVCC(HYST)
Internal V
CC
Undervoltage Lockout Hysteresis
Ideal Diode Control
∆V
FWD(REG)
∆V
DGATE
∆V
DGATE(ST)
I
D2SRC
I
CPO(UP)
I
DGATE(FPU)
I
DGATE(FPD)
I
DGATE2(DN)
t
ON(DGATE)
t
OFF(DGATE)
t
PLH(DGATE2)
∆V
SENSE(TH)
V
SENSE
+
(UVL)
I
SENSE
+
I
SENSE–
I
CS
+
∆V
HGATE
∆V
HGATE(H)
I
HGATE(UP)
I
HGATE(DN)
I
HGATE(FPD)
t
PHL(SENSE)
t
OFF(HGATE)
t
D(HGATE)
t
P(HGATE)
Forward Regulation Voltage
(V
INn
– V
SENSE
+)
External N-Channel Gate Drive
(V
DGATE1
– V
IN1
) and (V
DGATE2
– V
D2SRC
)
Diode MOSFET On Detect Threshold
(V
DGATE1
– V
IN1
) and (V
DGATE2
– V
D2SRC
)
D2SRC Pin Current
CPOn Pull-Up Current
DGATEn Fast Pull-Up Current
DGATEn Fast Pull-Down Current
DGATE2 Off Pull-Down Current
DGATEn Turn-On Delay
DGATEn Turn-Off Delay
D2OFF Low to DGATE2 High
Current Limit Sense Voltage Threshold
(V
SENSE
+ – V
SENSE
–)
SENSE
+
Undervoltage Lockout
SENSE
+
Pin Current
SENSE
–
Pin Current
CS
+
Pin Current
External N-Channel Gate Drive
(V
HGATE
– V
OUT
)
Gate High Threshold (V
HGATE
– V
OUT
)
External N-Channel Gate Pull-Up Current
Gate Drive On, HGATE = 0V
External N-Channel Gate Pull-Down Current Gate Drive Off, OUT = 12V,
HGATE = OUT + 5V
External N-Channel Gate Fast Pull-Down
Current
Sense Voltage (SENSE
+
– SENSE
–
)
High to HGATE Low
ON Low to HGATE Low
EN
High to HGATE Low
SENSE
+
Low to HGATE Low
ON High,
EN
Low to HGATE Turn-On Delay
ON to HGATE Propagation Delay
Fast Turn-Off, OUT = 12V,
HGATE = OUT + 5V
∆V
SENSE
= 200mV, C
HGATE
= 10nF
FB = 1.3V
FB = 0V
SENSE
+
Rising
SENSE
+
= 12V
SENSE
–
= 12V
CS
+
= 12V, ∆V
SENSE
= 0V
IN < 7V, I = 0, –1µA
IN = 7V to 18V, I = 0, –1µA
IN < 7V, ∆V
FWD
= 0.15V; I = 0, –1µA
IN = 7V to 18V, ∆V
FWD
= 0.15V; I = 0, –1µA
DSTAT
Pulls Low, ∆V
FWD
= 50mV
D2SRC = 0V
CPO = IN = D2SRC = 2.9V
CPO = IN = D2SRC = 18V
∆V
FWD
= 0.2V, ∆V
DGATE
= 0V, CPO = 17V
∆V
FWD
= –0.2V, ∆V
DGATE
= 5V
D2OFF = 2V, ∆V
DGATE2
= 2.5V
∆V
FWD
= 0.2V , C
DGATE
= 10nF
∆V
FWD
= –0.2V, C
DGATE
= 10nF
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50
100
0.25
0.2
50
200
0.5
0.5
100
27.5
10.8
2
90
1.3
100
±1
14
14
4.8
–13
4
350
1
20
40
20
150
20
µA
µs
µs
µs
mV
mV
V
mV
mA
µA
µA
V
V
V
µA
mA
mA
µs
µs
µs
µs
ms
µs
Hot Swap Control
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l
l
l
l
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l
22.5
5.8
1.8
10
0.3
10
5
10
3.6
–7
1
100
25
8.3
1.9
50
0.8
40
7
12
4.2
–10
2
200
0.5
10
20
10
∆V
SENSE
+
(HYST)
SENSE
+
Undervoltage Lockout Hysteresis
SENSE
+
UVLO
DTMR = INTV
CC
ON = Step 0.8V to 2V
50
100
10
For more information
www.linear.com/LTC4236
3
4236f
LTC4236
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted.
SYMBOL
Inputs
V
D2OFF(H,TH)
V
D2OFF(L,TH)
∆V
D2OFF(HYST)
V
IN(TH)
∆V
ON(HYST)
∆V
FB(HYST)
V
ON(RESET)
I
IN(LEAK)
V
EN(TH)
∆V
EN(HYST)
I
EN(UP)
V
TMR(H)
V
TMR(L)
I
FTMR(UP)
I
FTMR(DN)
D
RETRY
I
DTMR(UP)
I
DTMR(DN)
∆V
DTMR(TH)
t
RST(ON)
t
PG(FB)
Outputs
I
OUT
V
OL
V
OH
I
OH
I
PU
Current Monitor
∆V
REG
∆V
SENSE(FS)
V
IMON(OS)
G
IMON
V
IMON(MAX)
V
IMON(MIN)
R
IMON(OUT)
Floating Regulator Voltage
(V
SENSE
+ – V
REG
)
Input Sense Voltage Full Scale
(V
SENSE
+ – V
SENSE
–)
IMON Input Offset Voltage
IMON Voltage Gain
IMON Maximum Output Voltage
IMON Minimum Output Voltage
IMON Output Resistance
I
REG
= ±1µA
SENSE
+
= 12V
∆V
SENSE
= 0V
∆V
SENSE
= 20mV and 5mV
∆V
SENSE
= 70mV, 5V ≤ SENSE
+
≤ 18V
∆V
SENSE
= 35mV, SENSE
+
= 2.9V
∆V
SENSE
= 200µV
∆V
SENSE
= 200µV
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l
elecTrical characTerisTics
PARAMETER
D2OFF Pin High Threshold
D2OFF Pin Low Threshold
D2OFF Pin Hysteresis
ON, FB Pin Threshold Voltage
ON Pin Hysteresis
FB Pin Hysteresis
ON Pin Fault Reset Threshold Voltage
Input Leakage Current (ON, FB, D2OFF)
EN
Pin Threshold Voltage
EN
Pin Hysteresis
EN
Pull-Up Current
FTMR, DTMR Pin High Threshold
FTMR, DTMR Pin Low Threshold
FTMR Pull-Up Current
FTMR Pull-Down Current
Auto-Retry Duty Cycle
DTMR Pull-Up Current
DTMR Pull-Down Current
DTMR Pin Threshold Voltage
(V
DTMR
– V
INTVCC
)
ON Low to
FAULT
High
FB Low to
PWRGD
High
OUT Pin Current
Output Low Voltage
(FAULT,
PWRGD, DSTAT1, DSTAT2)
Output High Voltage (FAULT,
PWRGD)
Input Leakage Current
(FAULT,
PWRGD, DSTAT1, DSTAT2)
Output Pull-Up Current (FAULT,
PWRGD)
CONDITIONS
D2OFF Rising
D2OFF Falling
Voltage Rising
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MIN
1.21
1.19
10
1.21
40
10
0.57
1.185
60
–7
1.198
0.15
–80
1.3
0.07
–8
1
–0.1
TYP
1.235
1.215
20
1.235
80
20
0.6
0
1.235
110
–10
1.235
0.2
–100
2
0.15
–10
5
–0.3
20
20
40
2.5
0.15
0.4
MAX
1.26
1.24
30
1.26
120
30
0.63
±1
1.284
200
–13
1.272
0.25
–120
2.7
0.23
–12
10
–0.5
40
40
100
4
0.4
1.2
±1
–13
4.6
UNITS
V
V
mV
V
mV
mV
V
µA
V
mV
µA
V
V
µA
µA
%
µA
mA
V
µs
µs
µA
mA
V
V
V
µA
µA
V
mV
ON Falling
V = 5V
EN
Rising
EN
= 1V
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l
l
FTMR = 1V, In Fault Mode
FTMR = 2V, No Faults
DTMR = 0.6V
DTMR = 1.5V
t
D(HGATE)
Start-Up Delay
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OUT = 11V, IN = 12V, ON = 2V
OUT = 13V, IN = 12V, ON = 2V
I = 1mA
I = 3mA
I = –1µA
V = 18V
V = 1.5V
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INTV
CC
– 1 INTV
CC
– 0.5
0
–7
3.6
25
±150
99
3.5
2.7
15
20
100
101
5.5
2.9
40
27
–10
4.1
µV
V/V
V
V
mV
kΩ
4236f
4
For more information
www.linear.com/LTC4236
LTC4236
elecTrical characTerisTics
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to GND unless otherwise
specified.
Note 3:
An internal clamp limits the DGATE1 and CPO1 pins to a minimum
of 10V above and a diode below IN1. Driving these pins to voltages beyond
the clamp may damage the device.
Note 4:
An internal clamp limits the DGATE2 and CPO2 pins to a minimum
of 10V above and a diode below D2SRC. Driving these pins to voltages
beyond the clamp may damage the device.
Note 5:
An internal clamp limits the HGATE pin to a minimum of 10V
above and a diode below OUT. Driving this pin to voltages beyond the
clamp may damage the device.
Note 6:
Thermal resistance is specified when the exposed pad is soldered
to a 3" x 5" , four layer, FR4 board.
For more information
www.linear.com/LTC4236
5
4236f
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