LTC4411
2.6A Low Loss
Ideal Diode in ThinSOTTM
U
DESCRIPTIO
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
Low Loss Replacement for PowerPathTM
OR’ing Diodes
Small Regulated Forward Voltage (28mV)
2.6A Maximum Forward Current
Low Forward ON Resistance (140mΩ Max)
Low Reverse Leakage Current ( VIH
VIN = 3.6V
VOUT = 3.7V
VIN = 3.6V
VOUT = 3.7V
VIN = 0V, VOUT = 5.5V
VIN = 3.6V
VIN = 3.6V
VIN = 3.6V, 100mA < ILOAD < 500mA
VIN = 3.6V, ILOAD = 1000mA
VIN Rising, 0°C < TA < 85°C
VIN Rising
VIN Falling
MAX
5.5
UNITS
V
µA
40
●
●
1.3
22
1.8
25
2.3
µA
µA
●
14
17
23
µA
●
–1
8
–4
1
28
14
140
245
2.5
2.6
µA
mV
mV
mΩ
mΩ
V
V
●
●
●
●
VIN = 3.6V, VOUT > VIN + VRTO,
VCTL > VTH + VHYST
VIN = 3.6V, VOUT < VIN – VFWD,
VCTL < VTH – VHYST
VTH = (VIL + VIH)/2
VHYST = (VIH – VIL)
VOUT < VIN = 3.6V, VCTL = 1.5V
TYP
17
5
100
140
1.6
7
V
11
18
µA
1
µA
1.2
1.1
1.4
1.25
µs
µs
530
mV
mV
µA
–1
●
390
●
2
460
90
3.5
1.8
2.6
6
Short-Circuit Response
IOC
Current Limit
VIN = 3.6V (Note 5)
IQOC
Quiescent Current While in
Overcurrent Operation
VIN = 3.6V, IOUT = 1.8A
575
A
1100
µA
4411fa
2
LTC4411
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 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: TJ is calculated from the ambient temperature TA and power
dissipation PD according to the following formula:
TJ = TA + (PD • 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.
Note 4: Quiescent current increases with load current, refer to plot of IQF
vs ILOAD.
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.
Measured Thermal Resistance (2-Layer Board*)
COPPER AREA
TOPSIDE
BACKSIDE
BOARD
AREA
THERMAL RESISTANCE
JUNCTION-TO-AMBIENT
2500mm2
2500mm2
2500mm2
125°C/W
1000mm2
2500mm2
2500mm2
125°C/W
225mm2
2500mm2
2500mm2
130°C/W
100mm2
2500mm2
2500mm2
135°C/W
50mm2
2500mm2
2500mm2
150°C/W
*Each layer uses one ounce copper
U W
TYPICAL PERFOR A CE CHARACTERISTICS
0.5
0.4
100
0.30
TA = –40°C
TA = 0°C
TA = 40°C
TA = 80°C
TA = 120°C
0.3
0.2
0.1
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
4411 G01
0.20
0.15
0.10
0.05
0
10
TA = –40°C
TA = 0°C
TA = 40°C
TA = 80°C
TA = 120°C
0.25
RESISTANCE (Ω)
TA = –40°C
TA = 0°C
TA = 40°C
TA = 80°C
TA = 120°C
FORWARD VOLTAGE (V)
QUIESCENT CURRENT (µA)
1000
RFWD and RON vs ILOAD at
VIN = 3.6V
VFWD vs ILOAD at VIN = 3.6V
Typical IQF vs ILOAD at VIN = 3.6V
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
4411 G02
0
0
0.5
1.0
1.5
LOAD CURRENT (A)
2.0
4411 G03
4411fa
3
LTC4411
U W
TYPICAL PERFOR A CE CHARACTERISTICS
RFWD vs Temperature at
VIN = 3.6V
RFWD vs VSUPPLY
0.150
TA = –40°C
TA = 0°C
TA = 40°C
0.100
0.075
IQROUT CURRENT (A)
0.15
RFWD (Ω)
RFWD (Ω)
100µ
TA = 80°C
TA = 120°C
0.125
0.050
0.10
0.05
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
0
–40 –20
0
20 40 60 80
TEMPERATURE (°C)
4411 G04
LEAKAGE CURRENT (A)
1µ
100n
0
5
1
2
3
4
REVERSE VOLTAGE (V)
5
6
4411 G06
CTL Turn-Off
VCTRL
500mV/DIV
VCTRL
500mV/DIV
VSTAT
2V/DIV
VSTAT
2V/DIV
VOUT
2V/DIV
IOUT
50mA/DIV
200µs/DIV
2
3
4
REVERSE VOLTAGE (V)
TA = –40°C
TA = 0°C
TA = 40°C
TA = 80°C
TA = 120°C
100n
100 120
VOUT
2V/DIV
IOUT
500mA/DIV
1
1µ
CTL Turn-On
TA = 60°C
TA = 80°C
TA = 100°C
TA = 120°C
0
10µ
4411 G05
ILEAK vs VREVERSE, VIN = 0V
10µ
10n
IQROUT vs VREVERSE at VIN = 0V
0.20
4411 G08
20µs/DIV
4411 G09
6
4411 G07
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 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) PullDown. 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 indicates the conducting status of the LTC4411. If the part is
forward biased (VIN > VOUT + VFWD) this pin will be Hi-Z.
If the part is reverse biased (VOUT > VIN + VRTO), 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.
4411fa
4
LTC4411
W
BLOCK DIAGRA
+
IN
–
1
5 OUT
P1
–+
–
VGATE
+
GND
2
OVERTEMP
SHDB
VREF
CTL
–
+
OFF
4 STAT
A
UVLO
OUTMAX
3
3µA
VB
VB
10µA
4411 F02
Figure 2. Detailed Block Diagram
U
OPERATIO
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 (VDD) will be supplied from the IN pin.
The amplifier (A) will deliver a voltage proportional to the
difference between VIN and VOUT to the gate (VGATE) of the
internal P-channel MOSFET (P1), driving this gate voltage
below VIN. This will turn on P1. As P1 conducts, VOUT will
be pulled up towards VIN. The LTC4411 will then control
VGATE 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,
VGATE will be controlled to maintain a low forward voltage
drop. If the load current exceeds P1’s ability to deliver the
current, as VGATE approaches GND, the P1 will behave as
a fixed resistor, with resistance RON, whereby the forward
voltage will increase with increased load current. As ILOAD
increases further (ILOAD > IMAX), 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
IOC
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 VON” regulation. As the current exceeds IFWD
the voltage drop will increase linearly with the current with
a slope of 1/RON; this operating mode is referred to as
“constant RON” regulation. As the current increases further, exceeding IMAX, the forward voltage drop will increase rapidly; this operating mode is referred to as
“constant ION” regulation. The characteristics for the
following parameters: RFWD, RON, VFWD, IFWD, and IMAX
are specified with the aid of Figure 3.
TA = 40°C
2.5
IMAX
2.0
LTC4411
IFWD
1.5
SLOPE
1/RON
1.0
SLOPE
1/RFWD
0.5
0
0
VFWD
SCHOTTKY
DIODE
0.25
0.5
0.75
FORWARD VOLTAGE (V)
1.0
4411 F03
Figure 3. LTC4411 vs Schottky Diode
Forward Conduction Characteristics
4411fa
5
LTC4411
U
OPERATIO
When the load current exceeds IMAX, an over current
condition is detected and the LTC4411 will limit the output
current. This will cause the output voltage to drop as the
load current exceeds the amount of current that the
LTC4411 can supply. This condition will increase the
power consumption within the LTC4411.
When an alternate power source is connected to the
output, the LTC4411 will sense the increased voltage at
OUT, and the amplifier (A) will increase the voltage at
VGATE. When VOUT is higher than VIN + VRTO, the internal
power source for the LTC4411 (VDD) will be diverted to
source current from the OUT pin. At the same time VGATE
will be pulled to VDD, which will turn off P1. The system is
now in the reverse turn-off mode. Power to the load is
being delivered from an alternate supply, and only a small
NORMAL OPERATION
REVERSE
BIASED
current is drawn from IN to sense the potential VIN. During
reverse turn-off mode the STAT pin will sink 10µA to
indicate that the diode is not conducting.
When the CTL input is asserted (high), P1 will have its gate
voltage pulled high, and the STAT pin will sink 10µA. A 3µA
pull-down current on the CTL pin will ensure a low level at
this input if it is left open circuited.
The overtemperature condition is detected when the
internal die temperature increases beyond 150°C. The
overtemperature condition will cause the gate amplifier
(A) as well as P1 to be shut off. When the internal die
temperature cools to below 140°C, the amplifier will turn
on and revert to normal operation. Note that prolonged
operation under overtemperature conditions will degrade
reliability.
ISTAT = 10µA
DIODE OFF
VCTL > VIH
VIN – VOUT < VFWD
CONTROL
SHUTDOWN
VIN – VOUT > VFWD
ISTAT = 0
CONSTANT VON DIODE ON
REGULATION
VCTL < VIL
VDD < 2.3
IOUT > IFWD
IOUT < IFWD
ISTAT = 0
CONSTANT RON DIODE ON
REGULATION
VDD > 2.4
TJ > 150°C
IOUT > IMAX IOUT < IMAX
ISTAT = 0
CONSTANT ION DIODE ON
REGULATION
ISTAT = 10µA
DIODE OFF
TJ < 140°C
WHERE:
VDD = MAX {VIN, VOUT}
VIL = VTH – VHYST/2
VIH = VTH + VHYST/2
UNDER
VOLTAGE
LOCK-OUT
ISTAT = 0
DIODE OFF
ISTAT = 0
OVER
DIODE OFF
TEMPERATURE
SHUTDOWN
4411 F04
Figure 4. State Transition Diagram
U
W
U
U
APPLICATIO S I FOR ATIO
INTRODUCTION
Automatic PowerPath Control
The LTC4411 is intended for power control applications
that include low loss diode ORing, fully automatic
switchover from a primary to an auxiliary source of power,
microcontroller controlled switchover from a primary to
an auxiliary source of power, load sharing between two or
more batteries, charging of multiple batteries from a
single charger and high side power switching.
Figure 1 illustrates an application circuit for automatic
switchover of a load between a battery and a wall adapter
or other power input. With initial application of the battery,
the load will be charged up as the LTC4411 turns on. The
LTC4411 will control the gate voltage of its internal MOSFET
to reduce the MOSFET’s voltage drop to a low forward
voltage (VFWD). The system is now in the forward regula4411fa
6
LTC4411
U
U
W
U
APPLICATIO S I FOR ATIO
tion mode, the forward voltage will be kept low by controlling the gate voltage of the internal MOSFET to react to
changes in load current. Should the wall adapter input be
applied, the Schottky diode will pull up the output voltage,
connected to the load, above the battery voltage. The
LTC4411 will sense that the output voltage is higher than
the battery voltage and will turn off the internal MOSFET.
The STAT pin will then sink current indicating an auxiliary
input is connected. The battery is now supplying no load
current and all load current flows through the Schottky
diode.
Microcontrolled PowerPath Monitoring and Control
Figure 6 illustrates an application circuit for microcontroller
monitoring and control of two power sources. The
microcontroller’s analog inputs, perhaps with the aid of a
resistor voltage divider, monitors each supply input and
commands the LTC4411 through the CTL input. Back-toback MOSFETs are used so that the parasitic drain-source
diode will not power the load when the MOSFET is turned
off (dual MOSFETs in one package are commercially
available).
turn off and no load current will be drawn from the
batteries. The STAT pins provide information as to which
input is supplying the load current. This concept can be
expanded to more power inputs.
Multiple Battery Charging
Figure 7 illustrates an application circuit for automatic dual
battery charging from a single charger. Whichever battery
has the lower voltage will receive the charging current until
both battery voltages are equal, then both will be charged.
When both are charging simultaneously, the higher capacity battery will get proportionally higher current from
the charger. For Li-Ion batteries, both batteries will achieve
the float voltage minus the forward regulation voltage of
40mV. This concept can apply to more than two batteries.
The STAT pin provides information as to which batteries
are being charged. For intelligent control, the CTL pin input
can be used with a microcontroller as shown in Figure 5.
WALL
ADAPTER
INPUT
CIN
1µF
2
BAT1
AUXILIARY P-CHANNEL
MOSFETS
AUXILIARY
POWER
SOURCE
R1
470k
2
BAT2
1
C1
10µF
2
3
C1: C0805C106K8PAC
C2: C1206C475K8PAC
5
IN
OUT
LTC4411
GND
CTL
3
OUT
LTC4411
GND
IN
CTL
STAT
VCC
470k
OUT
LTC4411
GND
VCC
470k
WHEN BOTH STATUS LINES ARE
HIGH, THEN BOTH BATTERIES
ARE SUPPLYING LOAD CURRENT.
WHEN BOTH STATUS LINES ARE
LOW, THEN WALL ADAPTER IS
PRESENT AND SUPPLYING FULL
LOAD CURRENT
STATUS IS HIGH WHEN
BAT2 IS SUPPLYING
LOAD CURRENT
STAT
C2
4.7µF
TO
LOAD
STATUS IS HIGH WHEN
BAT1 IS SUPPLYING
LOAD CURRENT
4
IN
CTL
COUT
4.7µF
5
LOAD
CIN: C0805C105K8PAC
COUT: C1206C475K8PAC
4
STAT
3
1
CIN
1µF
MICROCONTROLLER
PRIMARY
POWER
SOURCE
1
STATUS
4411 F05
Figure 5. Automatic Switchover of Load Between a
Primary and an Auxiliary Power Source with External
Dual P-Channel MOSFETs
Figure 6. Dual Battery Load Sharing with Automatic
Switchover of Load from Batteries to Wall Adapter
BATTERY
CHARGER
INPUT
1
OUT
LTC4411
2
GND
Load Sharing
Figure 6 illustrates an application circuit for dual battery
load sharing with automatic switchover of load from
batteries to wall adapter. Whichever battery is capable of
supplying the higher voltage will provide the load current
until it is discharged to the voltage of the other battery. The
load will then be shared between the two batteries according to the capacity of each battery. The higher capacity
battery will provide proportionally higher current to the
load. When a wall adapter input is applied, both LTC4411s
4411 F06
3
IN
CTL
STAT
TO LOAD OR
PowerPath
CONTROLLER
5
VCC
BAT1
470k
4
STATUS IS HIGH
WHEN BAT1 IS
CHARGING
TO LOAD OR
PowerPath
CONTROLLER
1
2
3
IN
OUT
LTC4411
GND
CTL
STAT
BAT2
VCC
470k
STATUS IS HIGH
WHEN BAT2 IS
CHARGING
4411 F07
Figure 7. Automatic Dual Battery Charging
from a Single Charging Source
4411fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
LTC4411
U
W
U U
APPLICATIO S I FOR ATIO
High Side Power Switch
SUPPLY
INPUT
CIN
1µF
Figure 8 illustrates an application circuit for a logic controlled high side power switch. When the CTL pin is a
logical low, the LTC4411 will turn on, supplying current to
the load. When the CTL pin is a logical high, the LTC4411
will turn off and deny power to the load. If the load is
powered from another (higher voltage) source, the supply
connected to VIN remains disconnected from the load.
U
PACKAGE DESCRIPTIO
1
5
IN
OUT
LTC4411
2
GND
3
LOGIC
INPUT
TO
COUT LOAD
4.7µF
4
CTL
STAT
CIN: C0805C105K8PAC
COUT: C1206C475K8PAC
4411 F08
Figure 8. Logic Controlled High Side Power Switch
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1.90 BSC
S5 TSOT-23 0302
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1558/LTC1559
Backup Battery Controller with Programmable Output
Adjustable Backup Voltage from 1.2V NiCd Button Cell,
Includes Boost Converter
LTC1998
2.5µA, 1% Accurate Programmable Battery Detector
Adjustable Trip Voltage/Hysteresis, ThinSOT
LTC4054
800mA Standalone Linear Li-Ion Battery Charger
with Thermal Regulation in ThinSOT
No External MOSFET, Sense Resistor or Blocking Diode Required,
Charge Current Monitor for Gas Gauging, C/10 Charge Termination
LTC4350
Hot Swappable Load Share Controller
Allows N + 1 Redundant Supply, Equally Loads Multiple Power
Supplies Connected in Parallel
LTC4412/LTC4412HV
PowerPath Controller in ThinSOT
More Efficient than Diode OR’ing, Automatic Switching Between DC
Sources, Simplified Load Sharing, 3V ≤ VIN ≤ 36V (LTC4412HV)
4411fa
8
Linear Technology Corporation
LT/LT 0305 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2003
工商网监
湘ICP备2023018690号
