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LTC4411
1
4411f
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
s
Low Loss Replacement for PowerPath
TM
OR'ing Diodes
s
Small Regulated Forward Voltage (28mV Min)
s
2.6A Maximum Forward Current
s
Low Forward ON Resistance (140m
Max)
s
Low Reverse Leakage Current (<1
A)
s
2.6V to 5.5V Operating Range
s
Internal Current Limit Protection
s
Internal Thermal Protection
s
No External Active Components
s
Pin-Compatible Low-Power Replacement
for LTC4412
s
Low Quiescent Current (40
A typical)
s
Low-profile (1mm) 5-lead SOT-23 Package
2.6A Low Loss
Ideal Diode in ThinSOT
TM
The LTC
4411 is an ideal diode IC, capable of supplying up
to 2.6A from an input voltage between 2.6V and 5.5V. The
LTC4411 is housed in a 5-lead 1mm profile SOT-23
package.
The LTC4411 contains a 140m
P-channel MOSFET con-
necting IN to OUT. During normal forward operation, the
drop across the MOSFET is regulated to as low as 28mV.
Quiescent current is less than 40
A for load currents up to
100mA. If the output voltage exceeds the input voltage, the
MOSFET is turned off and less than 1
A of reverse current
flows from OUT to IN. Maximum forward current is limited
to a constant 2.6A (typical) and internal thermal limiting cir-
cuits protect the part during fault conditions.
An open-drain STAT pin indicates conduction status. The
STAT pin can be used to drive an auxiliary P-channel
MOSFET power switch connecting an alternate power
source when the LTC4411 is not conducting forward
current.
An active-high control pin turns off the LTC4411 and
reduces current consumption to less than 25
A. When
shut off, the LTC4411 indicates this condition with a low
voltage on the status signal.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Figure 1. Automatic Switchover of Load
Between a Battery and a Wall Adapter
IN
GND
CTL
OUT
STAT
LTC4411
WALL
ADAPTER
INPUT
TO
LOAD
4.7
F
STATUS OUTPUT
IS LOW WHEN WALL
ADAPTER IS SUPPLYING
LOAD CURRENT
BATTERY
CELL(S)
470k
4411 F01
V
CC
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
s
Cellular Phones
s
Handheld Computers
s
Digital Cameras
s
USB Peripherals
s
Uninterrupted Supplies
s
Logic Controlled Power Switch
LTC4411 vs Schottky Diode
Forward Voltage Characteristics
LTC4411
SCHOTTKY
DIODE
CONSTANT I
ON
CONSTANT
R
ON
CONSTANT
V
ON
V
FWD
FORWARD VOLTAGE (V)
LTC4411 FO2
SLOPE
1/R
ON
SLOPE
1/R
FWD
I
OC
I
MAX
I
FWD
CURRENT (A)
LTC4411
2
4411f
IN, OUT, STAT, CTL Voltage .......................... 0.3 to 6V
Operating Ambient Temperature Range
(Note 2) ...............................................40
C to 85
C
Operating Junction Temperature
(Note 3) .............................................40
C to 125
C
Storage Temperature Range ..................65
C to 125
C
Lead Temperature (Soldering, 10 sec).................. 300
C
ORDER PART
NUMBER
S5 PART
MARKING
T
JMAX
= 125
C,
JA
= 250
C/W (Note 3)
LTAEN
LTC4411ES5
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
5 OUT
4 STAT
IN 1
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC SOT-23
GND 2
CTL 3
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
, V
OUT
Operating Supply Range
q
2.6
5.5
V
I
QF
Quiescent Current In Forward Regulation
V
IN
= 3.6V, I
LOAD
= 100mA
40
A
(Note 4)
I
QRIN
Quiescent Current While in Reverse
V
IN
= 3.6V
q
1.3
1.8
2.3
A
Turn-Off. Current Drawn from V
IN
V
OUT
= 3.7V
I
QROUT
Quiescent Current While in Reverse
V
IN
= 3.6V
q
14
17
23
A
Turn-Off. Current Drawn from V
OUT
V
OUT
= 3.7V
I
LEAK
V
IN
Current When V
OUT
Supplies Power
V
IN
= 0V, V
OUT
= 5.5V
1
1
A
V
FWD
Forward Turn-On Voltage (V
IN
V
OUT
)
V
IN
= 3.6V
q
8
17
28
mV
V
RTO
Reverse Turn-Off Voltage (V
OUT
V
IN
)
V
IN
= 3.6V
0
5
14
mV
R
FWD
Forward ON Resistance,
(V
IN
-V
OUT
)/
(I
LOAD
) V
IN
= 3.6V, 80
A < I
LOAD
< 1A
q
100
140
m
R
ON
ON Resistance in Constant R
ON
Mode
V
IN
= 3.6V, I
LOAD
= 1000mA
q
140
245
m
UVLO
Undervoltage Lockout
V
IN
Rising, 0
C < T
A
< 85
C
2.5
V
V
IN
Rising
q
2.6
V
V
IN
Falling
q
1.6
V
STAT Output
I
S(SNK)
STAT Pin Sink Current
V
IN
= 3.6V, V
OUT
> V
IN
+ V
RTO
,
7
11
18
A
V
CTL
> V
TH
+ V
HYST
I
S(OFF)
STAT Pin Off Current
V
IN
= 3.6V, V
OUT
< V
IN
V
FWD
,
1
1
A
V
CTL
< V
TH
V
HYST
t
S(ON)
STAT Pin Turn-On Time
1.2
1.4
s
t
S(OFF)
STAT Pin Turn-Off Time
1.1
1.25
s
CTL Input
V
TH
CTL Input Threshold Voltage
V
TH
= (V
IL
+ V
IH
)/2
q
390
460
530
mV
V
HYST
CTL Input Hysteresis
V
HYST
= (V
IH
V
IL
)
90
mV
I
CTL
CTL Input Pull-Down Current
V
OUT
< V
IN
= 3.6V, V
CTL
= 1.5V
q
2
3.5
6
A
Short-Circuit Response
I
OC
Current Limit
V
IN
= 3.6V (Note 5)
1.8
2.6
A
I
QOC
Quiescent Current While In
V
IN
= 3.6V, I
OUT
= 1.8A
575
1100
A
Overcurrent Operation
LTC4411
3
4411f
LOAD CURRENT (A)
0.5
1.5
2.5
1.0
2.0
3.0
4411 G01
QUIESCENT CURRENT (
A)
0
LOAD CURRENT (A)
LOAD CURRENT (A)
0.5
1.5
2.5
1.0
2.0
3.0
0
T
A
= 40
C
T
A
= 0
C
T
A
= 40
C
T
A
= 80
C
T
A
= 120
C
FORWARD VOLTAGE (V)
4411 G02
0
RESISTANCE (
)
0.5
1.0
1.5
2.0
4411 G03
1000
0.5
0.4
0.3
0.2
0.1
0.15
0.10
0.30
0.25
0.20
0.05
0
100
10
0
T
A
= 40
C
T
A
= 0
C
T
A
= 40
C
T
A
= 80
C
T
A
= 120
C
T
A
= 40
C
T
A
= 0
C
T
A
= 40
C
T
A
= 80
C
T
A
= 120
C
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 6)
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Typical I
QF
vs I
LOAD
at V
IN
= 3.6V
V
FWD
vs I
LOAD
at V
IN
= 3.6V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC4411E is guaranteed to meet performance specifications
from 0
C to 70
C. Specifications over the 40
C to 85
C ambient
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
150
C/W)
The following table lists thermal resistance for several different board sizes
and copper areas. All measurements were taken in still air on 3/32" FR-4
board with the device mounted on topside.
Measured Thermal Resistance (2-Layer Board*)
COPPER AREA
BOARD
THERMAL RESISTANCE
TOPSIDE
BACKSIDE
AREA
JUNCTION-TO-AMBIENT
2500mm
2
2500mm
2
2500mm
2
125
C/W
1000mm
2
2500mm
2
2500mm
2
125
C/W
225mm
2
2500mm
2
2500mm
2
130
C/W
100mm
2
2500mm
2
2500mm
2
135
C/W
50mm
2
2500mm
2
2500mm
2
150
C/W
*Each layer uses one ounce copper
Note 4: Quiescent current increases with load current, refer to plot of I
QF
vs I
LOAD
.
Note 5: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125
C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 6: Current into a pin is positive and current out of a pin is negative.
All voltages are referenced to GND.
R
FWD
and R
ON
vs I
LOAD
at
V
IN
= 3.6V
LTC4411
4
4411f
U
U
U
PI FU CTIO S
IN (Pin 1): Ideal Diode Anode and Positive Power Supply
for LTC4411. When operating LTC4411 as a switch it must
be bypassed with a low ESR ceramic capacitor of 1
F. X5R
and X7R dielectrics are preferred for their superior voltage
and temperature characteristics.
GND (Pin 2): Power and Signal Ground for the IC.
CTL (Pin 3): Controlled Shutdown Pin. Weak (3
A) Pull-
Down. Pull this pin high to shut down the IC. Tie to GND
to enable. Can be left floating when not in use.
STAT (Pin 4): Status Condition Indicator. This pin indi-
cates the conducting status of the LTC4411. If the part is
forward biased (V
IN
> V
OUT
+ V
FWD
) this pin will be Hi-Z.
If the part is reverse biased (V
OUT
> V
IN
+ V
RTO
), then this
pin will pull down 10
A through an open-drain. When
terminated to a high voltage through a 470k resistor, a
high voltage indicates diode conducting. May be left
floating or grounded when not in use.
OUT (Pin 5): Ideal Diode Cathode and Output of the
LTC4411. Bypass OUT with a nominal 1m
ESR capacitor
of at least 4.7
F. The LTC4411 is stable with ESRs down
to 0.2m
. However stability improves with higher ESRs.
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
R
FWD
vs V
SUPPLY
R
FWD
vs Temperature
at
V
IN
= 3.6V
I
QROUT
vs V
REVERSE
at V
IN
= 0V
0
1
2
3
4
5
6
REVERSE VOLTAGE (V)
LEAKAGE CURRENT (A)
10
1
100n
10n
4411 G07
T
A
= 60
C
T
A
= 80
C
T
A
= 100
C
T
A
= 120
C
SUPPLY VOLTAGE (V)
2.5
R
FWD
(
)
0.150
0.125
0.100
0.075
0.050
3.0
3.5
4.0
4.5
4411 G04
5.0
5.5
TEMPERATURE (
C)
40
R
FWD
(
)
120
4411 G05
0
20
20
100
40
60
80
REVERSE VOLTAGE (V)
0
1
2
3
4
5
6
I
QROUT
CURRENT (A)
100
10
1
100n
4411 G06
T
A
= 40
C
T
A
= 0
C
T
A
= 40
C
0.15
0.10
0.20
0.05
0
T
A
= 80
C
T
A
= 120
C
4411 G08
4411 G09
T
A
= 40
C
T
A
= 0
C
T
A
= 40
C
T
A
= 80
C
T
A
= 120
C
V
CTRL
500mV/DIV
V
STAT
2V/DIV
V
OUT
2V/DIV
I
OUT
500mA/DIV
200
s/DIV
V
CTRL
500mV/DIV
V
STAT
2V/DIV
V
OUT
2V/DIV
I
OUT
50mA/DIV
20
s/DIV
I
LEAK
vs V
REVERSE
,V
IN
= 0V
CTL Turn-On
CTL Turn-Off
LTC4411
5
4411f
BLOCK DIAGRA
W
Figure 2. Detailed Block Diagram
+
+
+
P1
V
B
V
B
OVERTEMP
UVLO
OUT
MAX
10
A
3
A
V
REF
OFF
SHDB
+
3
1
5
4
2
STAT
OUT
CTL
IN
GND
4411 F03
A
V
GATE
Figure 3. LTC4411 vs Schottky Diode
Forward Conduction Characteristics
OPERATIO
U
The LTC4411 operation is described with the aid of
Figure 3. Forward regulation for the LTC4411 has three
operation modes depending on the magnitude of the load
current. For small load currents, the LTC4411 will provide
a constant voltage drop; this operating mode is referred to
as "constant V
ON
" regulation. As the current exceeds I
FWD
the voltage drop will increase linearly with the current with
a slope of 1/R
ON
; this operating mode is referred to as
"constant R
ON
" regulation. As the current increases fur-
ther, exceeding I
MAX
, the forward voltage drop will in-
crease rapidly; this operating mode is referred to as
"constant I
ON
" regulation. The characteristics for the
following parameters: R
FWD
, R
ON
, V
FWD
, I
FWD
, and I
MAX
are specified with the aid of Figure 3.
Operation begins when the power source at IN rises above
the UVLO voltage of 2.4V (typ) and the CTL (control) pin
is low. If only the voltage at the IN pin is present, the power
source to LTC4411 (V
DD
) will be supplied from the IN pin.
The amplifier (A) will deliver a voltage proportional to the
difference between V
IN
and V
OUT
to the gate (V
GATE
) of the
internal P-channel MOSFET (P1), driving this gate voltage
below V
IN
. This will turn on P1. As P1 conducts, V
OUT
will
be pulled up towards V
IN
. The LTC4411 will then control
V
GATE
to maintain a low forward voltage drop. The system
is now in forward regulation and the load at OUT will be
powered from the supply at IN. As the load current varies,
V
GATE
will be controlled to maintain a low forward voltage
drop. If the load current exceeds P1's ability to deliver the
current, as V
GATE
approaches GND, the P1 will behave as
a fixed resistor, with resistance R
ON
, whereby the forward
voltage will increase with increased load current. As I
LOAD
increases further (I
LOAD
> I
MAX
) the LTC4411 will regulate
the load current as described below. During the forward
regulation mode of operation the STAT pin will be an open
circuit.
V
FWD
I
OC
I
MAX
I
FWD
FORWARD VOLTAGE (V)
0
LOAD CURRENT (A)
3.0
2.5
2.0
1.5
1.0
0.5
0
0.25
0.5
0.75
1.0
4411 F04
T
A
= 40
C
SLOPE
1/R
ON
SLOPE
1/R
FWD
SCHOTTKY
DIODE
LTC4411
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