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PDF LTC4364-1 Data sheet ( Hoja de datos )
| Número de pieza | LTC4364-1 | |
| Descripción | Surge Stopper | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
n Wide Operating Voltage Range: 4V to 80V
n Withstands Surges Over 80V with VCC Clamp
n Adjustable Output Clamp Voltage
n Ideal Diode Controller Holds Up Output Voltage
During Input Brownouts
n Reverse Input Protection to –40V
n Reverse Output Protection to –20V
n Overcurrent Protection
n Low 10μA Shutdown Current at 12V
n Adjustable Fault Timer
n 0.1% Retry Duty Cycle During Faults (LTC4364-2)
n Available in 4mm × 3mm 14-Lead DFN, 16-Lead MSOP,
and 16-Lead SO Packages
APPLICATIONS
n Automotive/Avionic Surge Protection
n Hot Swap/Live Insertion
n Redundant Supply ORing
n Output Port Protection
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.
LTC4364-1/LTC4364-2
Surge Stopper
with Ideal Diode
DESCRIPTION
The LTC®4364 surge stopper with ideal diode controller
protects loads from high voltage transients. It limits and
regulates the output during an overvoltage event, such
as load dump in automobiles, by controlling the voltage
drop across an external N-channel MOSFET pass device.
The LTC4364 also includes a timed, current limited circuit
breaker. In a fault condition, an adjustable fault timer must
expire before the pass device is turned off. The LTC4364-1
latches off the pass device while the LTC4364-2 automati-
cally restarts after a delay. The LTC4364 precisely monitors
the input supply for overvoltage (OV) and undervoltage
(UV) conditions. The external MOSFET is held off in un-
dervoltage and auto-retry is disabled in overvoltage.
An integrated ideal diode controller drives a second MOS-
FET to replace a Schottky diode for reverse input protec-
tion and output voltage holdup. The LTC4364 controls the
forward voltage drop across the MOSFET and minimizes
reverse current transients upon power source failure,
brownout or input short.
TYPICAL APPLICATION
4A, 12V Overvoltage Output Regulator with Ideal Diode
Withstands 200V 1ms Transient at VIN
VIN
12V
383k
CMZ5945B
68V
FDB33N25
FDB3682 10mΩ
2.2k 6.8nF 10Ω
VOUT
+
CLAMPED
AT 27V
22µF
UV
6V
90.9k
OV
60V
10k
VCC
SHDN
UV
OV
HGATE SOURCE DGATE SENSE
OUT
FB
LTC4364
102k
4.99k
GND
TMR
0.22µF
ENOUT
FLT
436412 TA01a
ENABLE
FAULT
Overvoltage Protector Regulates
Output at 27V During Input Transient
92V INPUT SURGE
VIN
20V/DIV
12V
VOUT
20V/DIV
12V
27V CLAMP (ADJUSTABLE)
50ms/DIV
CTMR = 6.8µF
ILOAD = 0.5A
4364 TA01b
12V
VIN
10V/DIV
Ideal Diode Holds Up Output
During Input Short
INPUT SHORTED
TO GND
CLOAD = 6300µF
ILOAD = 0.5A
VOUT 12V OUTPUT HELD UP
10V/DIV
1ms/DIV
4364 TA01c
436412f
1
1 page  
LTC4364-1/LTC4364-2
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs VCC
450 VCC = SOURCE = SENSE = OUT
400
350 ICC
300
250
200
150 ISNS + IOUT
100
50 ISRC
0
0 10 20 30 40 50 60
VCC (V)
70 80
436412 G01
ISNS + IOUT in Shutdown vs VCC
100 SOURCE = VCC
80
SNS = OUT = 48V
60
40
20 SNS = OUT = 24V
SNS = OUT = 12V
0
0 10 20 30 40 50 60 70 80
VCC (V)
436412 G04
∆VDGATE vs IDGATE
14 VCC = 12V
13
12
11
10
9
8
7
6
0 –2 –4 –6
IDGATE (µA)
–8 –10
436412 G07
ICC(SHDN) vs VCC
60 SHDN = 0
50
OUT = 0
40
30
20 OUT = VCC
10
0
0 10 20 30 40 50 60 70 80
VCC (V)
436412 G02
GATE Pull-Up Current vs VCC
–24 HGATE = DGATE = SOURCE = VCC
–20 ∆VSD = 100mV
HGATE
–16
–12
DGATE
–8
–4
0
4 6 8 10 12 20 40 60 80
VCC (V)
436412 G05
∆VHGATE vs VIN in Figure 1
14
12
10
8
6 R4 IN FIGURE 1
0Ω
4 2.2k
4.7k
10k
2
4 8 12 16 20 24
VIN (V)
436412 G08
ICC(SHDN) vs Temperature
16
SHDN = 0
14 VCC = 12V
12
10 OUT = 0
8
OUT = 12V
6
4
2
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
436412 G03
∆VHGATE vs IHGATE
14 VCC = 12V
13
12
11
10
9
8
7
6
0 –5 –10
IHGATE (µA)
–15 –20
436412 G06
∆VDGATE vs VIN in Figure 1
14
12
10
8
6 R4 IN FIGURE 1
0Ω
4 2.2k
4.7k
10k
2
4 8 12 16 20 24
VIN (V)
436412 G09
436412f
5
5 Page 
LTC4364-1/LTC4364-2
APPLICATIONS INFORMATION
Some power systems must cope with high voltage surges
of short duration such as those in automobiles. Load
circuitry must be protected from these transients, yet
critical systems may need to continue operating during
these events.
The LTC4364 drives an N-channel MOSFET (M1) at the
HGATE pin to limit the voltage and current to the load cir-
cuitry during supply transients or overcurrent events. The
selection of M1 is critical for this application. It must stay
on and provide a low impedance path from the input sup-
ply to the load during normal operation and then dissipate
power during overvoltage or overcurrent conditions. The
LTC4364 also drives a second N-channel MOSFET (M2) at
the DGATE pin as an ideal diode to protect the load from
damage during reverse polarity input conditions, and to
block reverse current flow in the event the input collapses.
A typical application circuit using the LTC4364 to regulate
the output at 27V during input surges with reverse input
protection is shown in Figure 1.
Overvoltage Fault
The LTC4364 limits the voltage at the OUT pin during an
overvoltage situation. An internal voltage amplifier regu-
lates the HGATE pin voltage to maintain 1.25V at the FB
pin. During this period of time, the N-channel MOSFET
M1 remains on and supplies current to the load. This
allows uninterrupted operation during brief overvoltage
transient events.
If the voltage regulation loop is engaged for longer than
the timeout period, set by the timer capacitor, an overvolt-
age fault is detected. The HGATE pin is pulled down to the
SOURCE pin by a 130mA current, turning M1 off. This
prevents M1 from being damaged during a long period
of overvoltage, such as during load dump in automobiles.
After the fault condition has disappeared and a cool down
period has transpired, the HGATE pin starts to pull high
again (LTC4364-2). The LTC4364-1 latches the HGATE pin
low after an overvoltage fault timeout and can be reset
using the SHDN or UV pin (see Resetting Faults).
Overcurrent Fault
The LTC4364 features an adjustable current limit that
protects against short circuits and excessive load current.
During an overcurrent event, the HGATE pin is regulated
to limit the current sense voltage across the SENSE and
OUT pins (∆VSNS) to 50mV when OUT is above 2.5V. The
current limit sense voltage is reduced to 25mV when OUT is
below 1.5V for additional protection during an output short.
A current sense resistor is placed between SENSE and
OUT and its value (RSNS) is determined by:
RSNS
=
∆VSNS
ILIM
where ILIM is the desired current limit.
MAX DC:
100V/–24V VIN
MAX 1ms 12V
TRANSIENT:
200V
M1
FDB33N25
D4
SMAJ24A
D3
1.5KE200A
R1
383k
1%
R2
90.9k
1%
R3
10k
1%
R4
2.2k
0.5W
R5
10Ω
R6
100Ω
C1
0.1µF
D1
CMZ5945B
68V
UV = 6V
D5
1N4148W
VCC HGATE
SHDN
UV
OV = 60V OV
GND
M2
FDB3682
RSNS
10mΩ
VOUT
+
4A
COUT CLAMPED AT 27V
22µF
CHG
0.1µF
SOURCE DGATE SENSE
LTC4364
TMR
CTMR
47nF
OUT
FB
R7
102k
1%
R8
4.99k
1%
ENOUT
FLT
ENABLE
FAULT
436412 F01
Figure 1. 4A, 12V Overvoltage Output Regulator with Reverse Current Protection
436412f
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC4364-1.PDF ] | |
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