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PDF LTC4359 Data sheet ( Hoja de datos )
| Número de pieza | LTC4359 | |
| Descripción | Ideal Diode Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC4359 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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LTC4359
Ideal Diode Controller with
Reverse Input Protection
Features
n Reduces Power Dissipation by Replacing a Power
Schottky Diode
n Wide Operating Voltage Range: 4V to 80V
n Reverse Input Protection to – 40V
n Low 9µA Shutdown Current
n Low 150μA Operating Current
n Smooth Switchover without Oscillation
n Controls Single or Back-to-Back N-Channel MOSFETs
n Available in 6-Lead (2mm × 3mm) DFN and 8-Lead
MSOP Packages
Applications
n Automotive Battery Protection
n Redundant Power Supplies
n Supply Holdup
n Telecom Infrastructure
n Computer Systems/Servers
n Solar Systems
Description
The LTC®4359 is a positive high voltage, ideal diode
controller that drives an external N-channel MOSFET to
replace a Schottky diode. It controls the forward-voltage
drop across the MOSFET to ensure smooth current delivery
without oscillation even at light loads. If a power source
fails or is shorted, a fast turn-off minimizes reverse cur-
rent transients. A shutdown mode is available to reduce
the quiescent current to 9μA for load switch and 14µA for
ideal diode applications.
When used in high current diode applications, the LTC4359
reduces power consumption, heat dissipation, voltage loss
and PC board area. With its wide operating voltage range,
the ability to withstand reverse input voltage, and high
temperature rating, the LTC4359 satisfies the demanding
requirements of both automotive and telecom applications.
The LTC4359 also easily ORs power sources in systems
with redundant supplies.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Typical Application
12V, 20A Automotive Reverse-Battery Protection
VIN
12V SMAT70A
70V
BSC028N06NS
SMAJ24A
24V
IN SOURCE
GATE OUT
SHDN
LTC4359
VSS
VOUT TO LOAD
47nF
4359 TA01
1k
Power Dissipation vs Load Current
10
8
SCHOTTKY DIODE (SBG2040CT)
6
4
POWER
SAVED
2
MOSFET (BSC028N06NS)
0
0 5 10 15 20
CURRENT (A)
4359 TA01a
For more information www.linear.com/LTC4359
4359fb
1
1 page  
Typical Performance Characteristics
Gate Turn-Off Time
vs Initial Overdrive
200 VIN = 12V
∆VSD = VINITIAL –1V
150
100
50
Gate Turn-Off Time
vs Final Overdrive
1500
VIN = 12V
∆VSD = 45mV VFINAL
1000
500
0
0 0.25 0.5 0.75 1
VINITIAL (V)
4359 G10
0
0
–0.25 –0.5 –0.75
–1
VFINAL (V)
4359 G11
LTC4359
Load Current
vs Forward Voltage Drop
10
FDMS86101
8
FDB3632
6
4
FDS3732
2
0
0 25 50 75 100
∆VSD (mV)
4359 G12
Pin Functions
Exposed Pad (DCB Package Only): Exposed pad may be
left open or connected to VSS.
GATE: Gate Drive Output. The GATE pin pulls high, enhanc-
ing the N-channel MOSFET when the load current creates
more than 30mV of voltage drop across the MOSFET.
When the load current is small, the gate is actively driven
to maintain 30mV across the MOSFET. If reverse current
flows, a fast pull-down circuit connects the GATE to the
SOURCE pin within 0.3μs, turning off the MOSFET.
IN: Voltage Sense and Supply Voltage. IN is the anode of
the ideal diode. The voltage sensed at this pin is used to
control the MOSFET gate.
NC (MS Package Only): No Connection. Not internally
connected.
OUT: Drain Voltage Sense. OUT is the cathode of the ideal
diode and the common output when multiple LTC4359s
are configured as an ideal diode-OR. It connects either di-
rectly or through a 2k resistor to the drain of the N-channel
MOSFET. The voltage sensed at this pin is used to control
the MOSFET gate.
SHDN: Shutdown Control Input. The LTC4359 can be
shut down to a low current mode by pulling the SHDN
pin below 0.6V. Pulling this pin above 2V or disconnect-
ing it allows an internal 2.6μA current source to turn the
part on. Maintain board leakage to less than 100nA for
proper operation. The SHDN pin can be pulled up to 100V
or down to – 40V with respect to VSS without damage. If
the shutdown feature is not used, connect SHDN to IN.
SOURCE: Source Connection. SOURCE is the return path
of the gate fast pull-down. Connect this pin as close as
possible to the source of the external N-channel MOSFET.
VSS: Supply Voltage Return and Device Ground.
For more information www.linear.com/LTC4359
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5 Page 
LTC4359
Applications Information
current flow when the MOSFETs are off. Q1 serves as the
ideal diode, while Q2 acts as a switch to control forward
power flow. On/off control is provided by the SHDN pin,
and C1 and R4 may be added if inrush control is desired.
When SHDN is driven high and provided VIN >VOUT + 30mV,
GATE sources 10µA and gradually charges C1, pulling up
both MOSFET gates. Q2 operates as a source follower and
IINRUSH
=
10µA • CLOAD
C1
If VIN <VOUT + 30mV, the LTC4359 will be activated but
holds Q1 and Q2 off until the input exceeds the output by
30mV. In this way normal diode behavior of the circuit is
preserved, but with soft starting when the diode turns on.
When SHDN is pulled low, GATE pulls the MOSFET gates
down quickly to SOURCE turning off both forward and
reverse paths, and the input current is reduced to 9µA.
While C1 and R4 may be omitted if soft starting is not
needed, R3 is necessary to prevent MOSFET parasitic
oscillations and must be placed close to Q2.
Layout Considerations
Connect the IN, SOURCE and OUT pins as close as possible
to the MOSFET source and drain pins. Keep the traces to
the MOSFET wide and short to minimize resistive losses as
shown in Figure 7. Place surge suppressors and necessary
transient protection components close to the LTC4359
using short lead lengths.
For the DFN package, pin spacing may be a concern at
voltages greater than 30V. Check creepage and clearance
guidelines to determine if this is an issue. To increase the
effective pin spacing between high voltage and ground pins,
leave the exposed pad connection open. Use no-clean flux
to minimize PCB contamination.
Figures 8 through 18 show typical applications of the
LTC4359.
1S
D8
VIN 2 S MOSFET D 7
3S
D6
4G
D5
SOURCE
GATE
OUT
VOUT
IN
DCB6
4359 F07a
Figure 7a. Layout, DCB6 Package
1S
D8
VIN
2S
D7
VOUT
MOSFET
3S
D6
4G
D5
GATE
SOURCE
IN
LTC4359
OUT
MS8
4359 F07b
Figure 7b. Layout, MS8 Package
Q1A
VINA BSC011N03LS
1.2V
IN SOURCE GATE
LTC4359
VSS
OUT
R1A
1k
–12V
Q1B
VINB BSC011N03LS
1.2V
IN SOURCE GATE
LTC4359
VSS
OUT
COUTA
47nF
COUTB
47nF
VOUT
1.2V
20A
CLOAD
R1B
1k
–12V
4359 F08
Figure 8. 1.2V Diode–OR
For more information www.linear.com/LTC4359
4359fb
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11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet LTC4359.PDF ] | |
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