create a near ideal diode function for power switchover or
load sharing. This permits highly efficient OR’ing of mul-
tiple power sources for extended battery life and low self-
heating. When conducting, the voltage drop across the
MOSFET is typically 20mV. For applications with a wall
adapter or other auxiliary power source, the load is auto-
matically disconnected from the battery when the auxiliary
source is connected. Two or more LTC4412s may be
interconnected to allow load sharing between multiple
batteries or charging of multiple batteries from a single
charger.
The wide supply operating range supports operation from
one to six Li-Ion cells in series. The low quiescent current
(11μA typical) is independent of the load current. The gate
driver includes an internal voltage clamp for MOSFET
protection.
The STAT pin can be used to enable an auxiliary P-channel
MOSFET power switch when an auxiliary supply is
detected. This pin may also be used to indicate to a
microcontroller that an auxiliary supply is connected. The
control (CTL) input enables the user to force the primary
MOSFET off and the STAT pin low.
The LTC4412 is available in a low profile (1mm) ThinSOT
package.
LTC4412 vs Schottky Diode
Forward Voltage Drop
1
CONSTANT
R
ON
APPLICATIO S
■
■
■
■
■
■
Cellular Phones
Notebook and Handheld Computers
Digital Cameras
USB-Powered Peripherals
Uninterruptable Power Supplies
Logic Controlled Power Switch
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
PowerPath and ThinSOT are trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
WALL
ADAPTER
INPUT
BATTERY
CELL(S)
1N5819
FDN306P
TO LOAD
LTC4412
6
V
IN
SENSE
5
2
GND GATE
4
3
CTL STAT
1
CURRENT (A)
C
OUT
V
CC
470k
4412 F01
STATUS OUTPUT
LOW WHEN WALL
ADAPTER PRESENT
Figure 1. Automatic Switchover of Load Between a Battery and a Wall Adapter
0
0.02
FORWARD VOLTAGE (V)
0.5
4412 F01b
U
LTC4412
CONSTANT
VOLTAGE
SCHOTTKY
DIODE
4412fa
U
U
1
LTC4412
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PI CO FIGURATIO
TOP VIEW
V
IN
1
GND 2
CTL 3
Supply Voltage (V
IN
) .................................. –14V to 36V
Voltage from V
IN
to SENSE ........................ – 28V to 28V
Input Voltage
CTL ........................................................– 0.3V to 36V
SENSE .................................................... –14V to 36V
Output Voltage
GATE ..................... –0.3V to the Higher of V
IN
+ 0.3V
or SENSE + 0.3V
STAT .....................................................– 0.3V to 36V
Operating Temperature Range
(Note 2) ............................................. – 40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 230°C/W
ORDER I FOR ATIO
LEAD FREE FINISH
LTC4412ES6#PBF
LTC4412IS6#PBF
LEAD BASED FINISH
LTC4412ES6
LTC4412IS6
TAPE AND REEL
PART MARKING*
LTA2
LTA2
PART MARKING*
LTA2
LTA2
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
LTC4412ES6#TRPBF
LTC4412IS6#TRPBF
TAPE AND REEL
LTC4412ES6#TR
LTC4412IS6#TR
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is indicated by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
,
V
SENSE
I
QFL
PARAMETER
Operating Supply Range
Quiescent Supply Current at Low Supply
While in Forward Regulation
Quiescent Supply Current at High Supply
While in Forward Regulation
Quiescent Supply Current at Low Supply
While in Reverse Turn-Off
Quiescent Supply Current at High Supply
While in Reverse Turn-Off
The
●
denotes specifications which apply over the full operating
temperature range, unless otherwise noted specifications are at T
A
= 25°C, V
IN
= 12V, CTL and GND = 0V. Current into a pin is positive
and current out of a pin is negative. All voltages are referenced to GND, unless otherwise specified.
CONDITIONS
V
IN
and/or V
SENSE
Must Be in This Range
for Proper Operation
V
IN
= 3.6V. Measure Combined Current
at V
IN
and SENSE Pins Averaged with
V
SENSE
= 3.5V and V
SENSE
= 3.6V (Note 3)
V
IN
= 28V. Measure Combined Current
at V
IN
and SENSE Pins Averaged with
V
SENSE
= 27.9V and V
SENSE
= 28V (Note 3)
V
IN
= 3.6V, V
SENSE
= 3.7V. Measure
Combined Current of V
IN
and SENSE Pins
V
IN
= 27.9V, V
SENSE
= 28V. Measure
Combined Current of V
IN
and SENSE Pins
●
●
MIN
2.5
I
QFH
●
I
QRL
I
QRH
2
U
6 SENSE
5 GATE
4 STAT
U
U
U
U
W W
W
W
U
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
TYP
MAX
28
UNITS
V
μA
11
19
15
26
μA
10
16
19
28
μA
μA
4412fa
LTC4412
ELECTRICAL CHARACTERISTICS
SYMBOL
I
QCL
I
QCH
I
LEAK
PARAMETER
Quiescent Supply Current at Low Supply
with CTL Active
Quiescent Supply Current at High Supply
with CTL Active
V
IN
and SENSE Pin Leakage Currents
When Other Pin Supplies Power
PowerPath Switch Forward Regulation
Voltage
PowerPath Switch Reverse Turn-Off
Threshold Voltage
GATE Active Forward Regulation
Source Current
Sink Current
GATE Clamp Voltage
GATE Off Voltage
GATE Turn-On Time
GATE Turn-Off Time
STAT Off Current
STAT Sink Current
STAT Turn-On Time
STAT Turn-Off Time
CTL Input Low Voltage
CTL Input High Voltage
CTL Input Pull-Down Current
CTL Hysteresis
The
●
denotes specifications which apply over the full operating
temperature range, unless otherwise noted specifications are at T
A
= 25°C, V
IN
= 12V, CTL and GND = 0V. Current into a pin is positive
and current out of a pin is negative. All voltages are referenced to GND, unless otherwise specified.
CONDITIONS
V
IN
= 3.6V, V
SENSE
= 0V, V
CTL
= 1V
V
IN
= 28V, V
SENSE
= 0V, V
CTL
= 1V
V
IN
= 28V, V
SENSE
= 0V; V
SENSE
= 28V, V
IN
= 0V
V
IN
= 14V, V
SENSE
= –14V; V
SENSE
= 14V, V
IN
= –14V
V
IN
– V
SENSE
, 2.5V
≤
V
IN
≤
28V
V
SENSE
– V
IN
, 2.5V
≤
V
IN
≤
28V
●
●
MIN
TYP
7
12
MAX
13
20
1
UNITS
μA
μA
μA
–3
0
PowerPath Controller
V
FR
V
RTO
10
10
20
20
32
32
mV
mV
GATE and STAT Outputs
(Note 4)
–1
25
Apply I
GATE
= 1μA, V
IN
= 12V,
V
SENSE
= 11.9V, Measure V
IN
– V
GATE
Apply I
GATE
= – 5μA, V
IN
= 12V,
V
SENSE
= 12.1V, Measure V
SENSE
– V
GATE
V
GS
< –3V, C
GATE
= 1nF (Note 5)
V
GS
> –1.5V, C
GATE
= 1nF (Note 6)
2.5V
≤
V
IN
≤
28V (Note 7)
2.5V
≤
V
IN
≤
28V (Note 7)
(Note 8)
(Note 8)
2.5V
≤
V
IN
≤
28V
2.5V
≤
V
IN
≤
28V
0.35V
≤
V
CTL
≤
28V
2.5V
≤
V
IN
≤
28V
●
●
●
●
I
G(SRC)
I
G(SNK)
V
G(ON)
V
G(OFF)
t
G(ON)
t
G(OFF)
I
S(OFF)
I
S(SNK)
t
S(ON)
t
S(OFF)
CTL Input
V
IL
V
IH
I
CTL
H
CTL
–2.5
50
7
0.13
110
13
–5
85
7.7
0.25
175
22
1
17
25
75
0.35
5.5
μA
μA
V
V
μs
μs
μA
μA
μs
μs
V
V
μA
mV
6.3
–1
6
0
10
4.5
40
0.5
0.9
1
0.635
3.5
135
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC4412E is guaranteed to meet performance specifications
from 0°C to 85°C operating temperature range. Specifications over the –
40°C to 85°C operating temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC4412IS6 is guaranteed over the – 40°C to 85°C operating temperature
range.
Note 3:
This results in the same supply current as would be observed with
an external P-channel MOSFET connected to the LTC4412 and operating in
forward regulation.
Note 4:
V
IN
is held at 12V and GATE is forced to 10.5V. SENSE is set at
12V to measure the source current at GATE. SENSE is set at 11.9V to
measure sink current at GATE.
Note 5:
V
IN
is held at 12V and SENSE is stepped from 12.2V to 11.8V to
trigger the event. GATE voltage is initially V
G(OFF)
.
Note 6:
V
IN
is held at 12V and SENSE is stepped from 11.8V to 12.2V to
trigger the event. GATE voltage is initially internally clamped at V
G(ON)
.
Note 7:
STAT is forced to V
IN
– 1.5V. SENSE is set at V
IN
– 0.1V to
measure the off current at STAT. SENSE is set V
IN
+ 0.1V to measure the
sink current at STAT.
Note 8:
STAT is forced to 9V and V
IN
is held at 12V. SENSE is stepped
from 11.8V to 12.2V to measure the STAT turn-on time defined when I
STAT
reaches one half the measured I
S(SNK).
SENSE is stepped from 12.2V to
11.8V to measure the STAT turn-off time defined when I
STAT
reaches one
half the measured I
S(SNK) .
4412fa
3
LTC4412
TYPICAL PERFOR A CE CHARACTERISTICS
V
FR
vs Temperature and
Supply Voltage
22
22
V
IN
= 2.5V
V
IN
= 28V
20
V
IN
= 2.5V
20
V
IN
= 28V
CURRENT (μA)
V
RTO
(mV)
V
FR
(mV)
18
–50 –25
50
25
75
0
TEMPERATURE (°C)
I
LEAK
vs Temperature
–0.20
7.1
CURRENT (μA)
VOLTAGE (V)
VOLTAGE (V)
–0.25
–0.30
–0.35
–50 –25
50
25
75
0
TEMPERATURE (°C)
t
G(ON)
vs Temperature
120
3.6V
≤
V
IN
≤
28V
C
GATE
= 1nF
13.5
CURRENT (μA)
TIME (μs)
TIME (μs)
110
100
–50 –25
50
25
75
0
TEMPERATURE (°C)
4
U W
100
100
V
RTO
vs Temperature and
Supply Voltage
1.05
Normalized Quiescent Supply
Current vs Temperature
3.6V
≤
V
IN
≤
28V
1.0
125
18
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
0.95
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
4412 G01
4412 G02
4412 G03
V
G(ON)
vs Temperature
8V
≤
V
IN
≤
28V
I
GATE
= 1μA
0.25
V
G(OFF)
vs Temperature and I
GATE
2.5V
≤
V
IN
≤
28V
0.20
I
GATE
= –10μA
0.15
I
GATE
= –5μA
0.10
I
GATE
= 0μA
7.0
0.05
125
6.9
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
4412 G04
4412 G05
4412 G06
t
G(OFF)
vs Temperature
3.6V
≤
V
IN
≤
28V
C
GATE
= 1nF
10.5
I
S(SNK)
vs Temperature and V
IN
V
STAT
= V
IN
– 1.5V
V
IN
= 28V
10.0
V
IN
= 2.5V
13.0
100
125
12.5
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
9.5
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
4412 G07
4412 G08
4412 G09
4412fa
LTC4412
PI FU CTIO S
V
IN
(Pin 1):
Primary Input Supply Voltage. Supplies power
to the internal circuitry and is one of two voltage sense
inputs to the internal analog controller (The other input to
the controller is the SENSE pin). This input is usually
supplied power from a battery or other power source
which supplies current to the load. This pin can be by-
passed to ground with a capacitor in the range of 0.1μF to
10μF if needed to suppress load transients.
GND (Pin 2):
Ground. Provides a power return for all the
internal circuits.
CTL (Pin 3):
Digital Control Input. A logical high input (V
IH
)
on this pin forces the gate to source voltage of the primary
P-channel MOSFET power switch to a small voltage (V
GOFF
).
This will turn the MOSFET off and no current will flow from
the primary power input at V
IN
if the MOSFET is configured
so that the drain to source diode does not forward bias. A
high input also forces the STAT pin to sink 10μA of current
(I
S(SNK)
). If the STAT pin is used to control an auxiliary P-
channel power switch, then a second active source of
power, such as an AC wall adaptor, will be connected to the
load (see Applications Information). An internal current
sink will pull the CTL pin voltage to ground (logical low) if
the pin is open.
STAT (Pin 4):
Open-Drain Output Status Pin. When the
SENSE pin is pulled above the V
IN
pin with an auxiliary
power source by about 20mV or more, the reverse turn-off
threshold (V
RTO
) is reached. The STAT pin will then go
from an open state to a 10μA current sink (I
S(SNK)
). The
STAT pin current sink can be used, along with an external
resistor, to turn on an auxiliary P-channel power switch
and/or signal the presence of an auxiliary power source to
a microcontroller.
GATE (Pin 5):
Primary P-Channel MOSFET Power Switch
Gate Drive Pin. This pin is directed by the power controller
to maintain a forward regulation voltage (V
FR
) of 20mV
between the V
IN
and SENSE pins when an auxiliary power
source is not present. When an auxiliary power source is
connected, the GATE pin will pull up to the SENSE pin
voltage, turning off the primary P-channel power switch.
SENSE (Pin 6):
Power Sense Input Pin. Supplies power to
the internal circuitry and is a voltage sense input to the
internal analog controller (The other input to the controller
is the V
IN
pin). This input is usually supplied power from
an auxiliary source such as an AC adapter or back-up
