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LTC4359IMS8#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
LTC4359
4
Rev D
For more information www.analog.com
TYPICAL PERFORMANCE CHARACTERISTICS
OUT Current
vs Forward Voltage Drop
SOURCE Current
vs Forward Voltage Drop
Total Negative Current
vs Negative Input Voltage
Gate Current
vs Forward Voltage Drop Gate Drive vs Gate Current
Gate Turn-Off Time
vs GATE Capacitance
IN Current in Regulation IN Current in Shutdown SOURCE Current in Shutdown
V
IN
(V)
0
I
IN
(µA)
100
150
80
4359 G01
50
0
20
40
60
200
V
IN
(V)
0
IN
30
40
20
10
0
20
40
60
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
T
A
= 125°C
IN = SOURCE = OUT
SHDN = 0V
V
SOURCE
(V)
0
I
SOURCE
(µA)
6
8
80
4359 G03
4
2
0
20
40
60
10
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
T
A
= 125°C
IN = SOURCE = OUT
SHDN = 0V
∆V
SD
(V)
–1
I
OUT
(µA)
80
120
1
4359 G04
40
0
–0.5
0
0.5
160
V
IN
= 4V
V
IN
= 12V
V
IN
= 48V
∆V
SD
(V)
–1
SOURCE
50
0
150
100
1
–50
–0.5
0
0.5
V
SOURCE
= 4V
V
SOURCE
> 12V
IN = SOURCE
VOLTAGE (V)
0
I
IN
+ I
SOURCE
+ I
SHDN
(mA)
–1
–1.5
–2
–40
4359 G06
–0.5
0
–10
–20
–30
IN = SOURCE= SHDN
∆V
SD
(mV)
–50
I
GATE
(µA)
10
0
–10
–20
150
4359 G07
20
30
40
0
50
100
V
IN
= V
SOURCE
= 12V
V
GATE
= V
IN
+2.5V
I
GATE
(µA)
0
∆V
GATE
(V)
10
–10
4359 G08
5
0
–5
–15
15
IN = SOURCE
V
IN
= 4V
V
IN
= 8V
V
IN
> 12V
C
GATE
(nF)
0
t
OFF
(ns)
400
600
8
4359 G09
200
0
2
4
6
10
800
V
IN
= 12V
∆V
SD
= 0.1V –1V
LTC4359
5
Rev D
For more information www.analog.com
PIN FUNCTIONS
Exposed Pad (DCB Package Only): Exposed pad may be
left open or connected to V
SS
.
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 (MS8 and S8 Packages): 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 V
SS
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.
V
SS
: Supply Voltage Return and Device Ground.
TYPICAL PERFORMANCE CHARACTERISTICS
Gate Turn-Off Time
vs Initial Overdrive
Gate Turn-Off Time
vs Final Overdrive
Load Current
vs Forward Voltage Drop
V
INITIAL
(V)
0
t
PD
(ns)
150
200
1
4359 G10
100
50
0
0.50.25
0.75
V
IN
= 12V
∆V
SD
= V
INITIAL
–1V
V
FINAL
(V)
0
t
PD
(ns)
1500
–1
4359 G11
1000
500
0
–0.5–0.25
–0.75
V
IN
= 12V
∆V
SD
= 45mV V
FINAL
∆V
SD
(mV)
0
CURRENT (A)
10
100
4359 G12
8
2
4
6
0
5025
75
FDMS86101
FDB3632
FDS3732
LTC4359
6
Rev D
For more information www.analog.com
BLOCK DIAGRAM
OPERATION
The LTC4359 controls an external N-channel MOSFET to
form an ideal diode. The GATE amplifier (see Block Dia-
gram) senses across IN and OUT and drives the gate of the
MOSFET to regulate the for
ward voltage to 30mV. As the
load current increases, GATE is driven higher until a point
is reached where the MOSFET is fully on. Further increases
in load current result in a forward drop of R
DS(ON)
• I
LOAD
.
If the load current is reduced, the GATE amplifier drives
the MOSFET gate lower to maintain a 30mV drop. If the
input voltage is reduced to a point where a forward drop
of 30mV cannot be supported, the GATE amplifier drives
the MOSFET off.
In the event of a rapid drop in input voltage, such as an
input short-circuit fault or negative-going voltage spike,
reverse current temporarily flows through the MOSFET.
This current is provided by any load capacitance and by
other supplies or batteries that feed the output in diode-
OR applications.
4359 BD
CHARGE PUMP
TYP. 500kHz
SHUTDOWN
–
+
–
+
FPD
COMP
GATE
AMP
30mV30mV
IN
2.6µA
SOURCE
SHDN
GATE
Q1
–1.7V
OUT
V
OUT
V
IN
V
SS
IN
+
–
+
–
–
+
NEGATIVE
COMP
The FPD COMP (Fast Pull-Down Comparator) quickly
responds to this condition by turning the MOSFET off in
300ns, thus minimizing the disturbance to the output bus.
The IN, SOURCE, GATE and SHDN pins are protected
against reverse inputs of up to –40V. The NEGATIVE COMP
detects negative input potentials at the SOURCE pin and
quickly pulls GATE to SOURCE, turning off the MOSFET
and isolating the load from the negative input.
When pulled low the SHDN pin turns off most of the
internal circuitry, reducing the quiescent current to 9µA
and holding the MOSFET off. The SHDN pin may be either
driven high or left open to enable the LTC4359. If left
open, an internal 2.6µA current source pulls SHDN high.
In applications where Q1 is replaced with back-to-back
MOSFETs, the SHDN pin serves as an on/off control for
the forward path, as well as enabling the diode function.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LTC4359IMS8#PBF

Mfr. #:
Buy LTC4359IMS8#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Power Management Specialized - PMIC Ideal Diode Cntr w/ Reverse In Prot
Lifecycle:
New from this manufacturer.
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