LTC4411
2.6A Low Loss
Ideal Diode in ThinSOT
TM
FEATURES
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DESCRIPTIO
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Low Loss Replacement for PowerPath
TM
OR’ing Diodes
Small Regulated Forward Voltage (28mV Min)
2.6A Maximum Forward Current
Low Forward ON Resistance (140mΩ Max)
Low Reverse Leakage Current (<1µA)
2.6V to 5.5V Operating Range
Internal Current Limit Protection
Internal Thermal Protection
No External Active Components
Pin-Compatible Low-Power Replacement
for LTC4412
Low Quiescent Current (40µA typical)
Low-profile (1mm) 5-lead SOT-23 Package
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 140mΩ 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 40µA for load currents up to
100mA. If the output voltage exceeds the input voltage, the
MOSFET is turned off and less than 1µA 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 25µA. 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.
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
APPLICATIO S
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Cellular Phones
Handheld Computers
Digital Cameras
USB Peripherals
Uninterrupted Supplies
Logic Controlled Power Switch
TYPICAL APPLICATIO
WALL
ADAPTER
INPUT
IN
BATTERY
CELL(S)
OUT
LTC4411
GND
CTL
STAT
TO
LOAD
V
CC
4.7µF
470k
I
MAX
I
OC
LTC4411
SLOPE
1/R
ON
CONSTANT
R
ON
CURRENT (A)
STATUS OUTPUT
IS LOW WHEN WALL
ADAPTER IS SUPPLYING
LOAD CURRENT
4411 F01
I
FWD
Figure 1. Automatic Switchover of Load
Between a Battery and a Wall Adapter
V
FWD
U
LTC4411 vs Schottky Diode
Forward Voltage Characteristics
CONSTANT I
ON
SLOPE
1/R
FWD
SCHOTTKY
DIODE
LTC4411 FO2
U
U
CONSTANT
V
ON
FORWARD VOLTAGE (V)
4411f
1
LTC4411
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
IN 1
GND 2
CTL 3
4 STAT
5 OUT
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
LTC4411ES5
S5 PART
MARKING
LTAEN
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W (Note 3)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 6)
SYMBOL
V
IN
, V
OUT
I
QF
I
QRIN
I
QROUT
I
LEAK
V
FWD
–V
RTO
R
FWD
R
ON
UVLO
PARAMETER
Operating Supply Range
Quiescent Current In Forward Regulation
(Note 4)
Quiescent Current While in Reverse
Turn-Off. Current Drawn from V
IN
Quiescent Current While in Reverse
Turn-Off. Current Drawn from V
OUT
V
IN
Current When V
OUT
Supplies Power
Forward Turn-On Voltage (V
IN
– V
OUT
)
Reverse Turn-Off Voltage (V
OUT
– V
IN
)
Forward ON Resistance,
∆(V
IN
-V
OUT
)/∆(I
LOAD
)
ON Resistance in Constant R
ON
Mode
Undervoltage Lockout
CONDITIONS
q
ELECTRICAL CHARACTERISTICS
MIN
2.6
TYP
40
MAX
5.5
V
IN
= 3.6V, I
LOAD
= 100mA
V
IN
= 3.6V
V
OUT
= 3.7V
V
IN
= 3.6V
V
OUT
= 3.7V
V
IN
= 0V, V
OUT
= 5.5V
V
IN
= 3.6V
V
IN
= 3.6V
V
IN
= 3.6V, 80µA < I
LOAD
< 1A
V
IN
= 3.6V, I
LOAD
= 1000mA
V
IN
Rising, 0°C < T
A
< 85°C
V
IN
Rising
V
IN
Falling
V
IN
= 3.6V, V
OUT
> V
IN
+ V
RTO
,
V
CTL
> V
TH
+ V
HYST
V
IN
= 3.6V, V
OUT
< V
IN
– V
FWD
,
V
CTL
< V
TH
– V
HYST
q
q
UNITS
V
µA
µA
µA
µA
mV
mV
mΩ
mΩ
V
V
V
1.3
14
–1
8
0
1.8
17
2.3
23
1
28
14
140
245
2.5
2.6
q
q
q
q
q
17
5
100
140
1.6
STAT Output
I
S(SNK)
I
S(OFF)
t
S(ON)
t
S(OFF)
CTL Input
V
TH
V
HYST
I
CTL
I
OC
I
QOC
STAT Pin Sink Current
STAT Pin Off Current
STAT Pin Turn-On Time
STAT Pin Turn-Off Time
CTL Input Threshold Voltage
CTL Input Hysteresis
CTL Input Pull-Down Current
Current Limit
Quiescent Current While In
Overcurrent Operation
7
–1
11
18
1
1.2
1.1
V
TH
= (V
IL
+ V
IH
)/2
V
HYST
= (V
IH
– V
IL
)
V
OUT
< V
IN
= 3.6V, V
CTL
= 1.5V
V
IN
= 3.6V (Note 5)
V
IN
= 3.6V, I
OUT
= 1.8A
q
q
1.4
1.25
530
6
390
2
1.8
460
90
3.5
2.6
575
Short-Circuit Response
A
1100
µA
4411f
2
U
µA
µA
µs
µs
mV
mV
µA
W
U
U
W W
W
LTC4411
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 6)
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
TOPSIDE
BACKSIDE
2500mm
2
1000mm
2
225mm
2
100mm
2
50mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
BOARD
AREA
2500mm
2
2500mm
2
2500mm
2
2500mm
2
2500mm
2
THERMAL RESISTANCE
JUNCTION-TO-AMBIENT
125°C/W
125°C/W
130°C/W
135°C/W
150°C/W
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.
ELECTRICAL CHARACTERISTICS
*Each layer uses one ounce copper
TYPICAL PERFOR A CE CHARACTERISTICS
Typical I
QF
vs I
LOAD
at V
IN
= 3.6V
1000
T
A
= –40°C
T
A
= 0°C
T
A
= 40°C
T
A
= 80°C
T
A
= 120°C
QUIESCENT CURRENT (µA)
FORWARD VOLTAGE (V)
0.3
100
RESISTANCE (Ω)
10
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
4411 G01
U W
V
FWD
vs I
LOAD
at V
IN
= 3.6V
0.5
T
A
= –40°C
T
A
= 0°C
T
A
= 40°C
T
A
= 80°C
T
A
= 120°C
0.30
0.25
0.20
0.15
0.10
0.05
0
R
FWD
and R
ON
vs I
LOAD
at
V
IN
= 3.6V
T
A
= –40°C
T
A
= 0°C
T
A
= 40°C
T
A
= 80°C
T
A
= 120°C
0.4
0.2
0.1
0
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
4411 G02
0
0.5
1.0
1.5
LOAD CURRENT (A)
2.0
4411 G03
4411f
3
LTC4411
TYPICAL PERFOR A CE CHARACTERISTICS
R
FWD
vs V
SUPPLY
0.150
T
A
= –40°C
T
A
= 0°C
T
A
= 40°C
0.20
T
A
= 80°C
T
A
= 120°C
0.15
I
QROUT
CURRENT (A)
0.125
R
FWD
(Ω)
R
FWD
(Ω)
0.100
0.075
0.050
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
I
LEAK
vs V
REVERSE
,V
IN
= 0V
10µ
T
A
= 60°C
T
A
= 80°C
T
A
= 100°C
T
A
= 120°C
V
CTRL
500mV/DIV
V
STAT
2V/DIV
LEAKAGE CURRENT (A)
1µ
100n
10n
0
1
2
3
4
REVERSE VOLTAGE (V)
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 1µF. 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 (3µA) 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 10µA 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 1mΩ ESR capacitor
of at least 4.7µF. The LTC4411 is stable with ESRs down
to 0.2mΩ. However stability improves with higher ESRs.
4411f
4
U W
5.0
5
R
FWD
vs Temperature at
V
IN
= 3.6V
100µ
I
QROUT
vs V
REVERSE
at V
IN
= 0V
10µ
0.10
1µ
0.05
5.5
4411 G04
0
–40 –20
0
20 40 60 80
TEMPERATURE (°C)
100 120
4411 G05
100n
0
1
T
A
= –40°C
T
A
= 0°C
T
A
= 40°C
T
A
= 80°C
T
A
= 120°C
2
3
4
REVERSE VOLTAGE (V)
5
6
4411 G06
CTL Turn-On
V
CTRL
500mV/DIV
V
STAT
2V/DIV
V
OUT
2V/DIV
I
OUT
50mA/DIV
CTL Turn-Off
V
OUT
2V/DIV
I
OUT
500mA/DIV
200µs/DIV
4411 G08
20µs/DIV
4411 G09
6
4411 G07
U
U
U
LTC4411
BLOCK DIAGRA
W
+
–
5 OUT
IN
1
–+
P1
V
GATE
GND
2
SHDB
V
REF
OFF
CTL
3
3µA
V
B
Figure 2. Detailed Block Diagram
OPERATIO
LOAD CURRENT (A)
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
–
+
–
+
OVERTEMP
A
UVLO
OUT
MAX
V
B
10µA
4 STAT
4411 F03
U
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.
3.0
I
OC
I
MAX
2.0
LTC4411
I
FWD
1.5
1.0
0.5
0
SLOPE
1/R
FWD
SLOPE
1/R
ON
2.5
T
A
= 40°C
SCHOTTKY
DIODE
1.0
4411 F04
0
V
FWD
0.25
0.5
0.75
FORWARD VOLTAGE (V)
Figure 3. LTC4411 vs Schottky Diode
Forward Conduction Characteristics
4411f
5
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