LTC4414
36V, Low Loss PowerPath
TM
Controller for Large PFETs
DESCRIPTIO
The LTC
®
4414 controls an external P-channel MOSFET to
create a near ideal diode function for power switchover.
This permits highly efficient OR’ing of multiple power
sources for extended battery life and low self- heating. When
conducting, the voltage drop across the MOSFET is typi-
cally 20mV. For applications with a wall adapter or other aux-
iliary power source, the load is automatically disconnected
from the battery when the auxiliary source is connected.
Two or more LTC4414s may be interconnected to allow
switchover between multiple batteries or charging of mul-
tiple batteries from a single charger.
The wide supply operating range supports operation from
one to eight Li-Ion cells in series. The low quiescent
current (30µA 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 micro-
controller that an auxiliary supply is connected. The con-
trol (CTL) input enables the user to force the primary
MOSFET off and the STAT pin low.
The LTC4414 is available in a low profile 8-lead MSOP
package.
FEATURES
■
■
■
■
■
■
■
■
■
■
■
Designed Specifically to Drive Large Q
G
PFETs
Very Low Loss Replacement for Power Supply
OR’ing Diodes
3.5V to 36V AC/DC Adapter Voltage Range
Minimal External Components
Automatic Switching Between DC Sources
Low Quiescent Current: 30µA
3V to 36V Battery Voltage Range
Limited Reverse Battery Protection
MOSFET Gate Protection Clamp
Manual Control Input
Space Saving 8-Lead MSOP Package
APPLICATIO S
■
■
■
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High Current Power Path Switch
Industrial and Automotive Applications
Uninterruptable Power Supplies
Logic Controlled Power Switch
Battery Backup Systems
Emergency Systems with Battery Backups
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATIO
UPS840
LTC4414 vs Schottky Diode Forward Voltage Drop
Automatic Switchover of Load Between a Battery and a Power Supply
POWER
SUPPLY
INPUT
BATTERY
CELL(S)
8.0
CONSTANT
R
ON
TO LOAD
LTC4414
V
IN
SENSE
GND
CTL
NC
GATE
STAT
NC
C
OUT
V
CC
470k
4414
TA01
CURRENT (A)
SUP75P03_07
3.6
LTC4414
CONSTANT
VOLTAGE
STATUS OUTPUT
LOW WHEN POWER
SUPPLY PRESENT
0
0.02
U
U
U
SCHOTTKY
DIODE
0.5
FORWARD VOLTAGE (V)
4414 TA01b
4414fc
1
LTC4414
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
STAT
CTL
GND
NC
1
2
3
4
8
7
6
5
GATE
V
IN
SENSE
NC
Supply Voltage (V
IN
) .................................. –14V to 40V
Voltage from V
IN
to SENSE ........................ – 40V to 40V
Input Voltage
CTL ........................................................– 0.3V to 40V
SENSE .................................................... –14V to 40V
Output Voltage
GATE ..................... –0.3V to the Higher of V
IN
+ 0.3V
or SENSE + 0.3V
STAT .....................................................– 0.3V to 40V
Operating Ambient Temperature Range (Note 2)
I Grade ............................................ – 40°C to 125°C
E Grade.............................................. – 40°C to 85°C
Operating Junction Temperature ......... – 40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
ORDER PART NUMBER
LTC4414EMS8
LTC4414IMS8
MS8 PART MARKING
LTBQF
LTBQG
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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
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
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
= 36V. Measure Combined Current
at V
IN
and SENSE Pins Averaged with
V
SENSE
= 35.9V and V
SENSE
= 36V (Note 3)
V
IN
= 3.6V, V
SENSE
= 3.7V. Measure
Combined Current of V
IN
and SENSE Pins
V
IN
= 35.9V, V
SENSE
= 36V. Measure
Combined Current of V
IN
and SENSE Pins
V
IN
= 3.6V, V
CTL
= 1V,
V
IN
– V
SENSE
= 0.9V
V
IN
= 36V, V
CTL
= 1V,
V
IN
– V
SENSE
= 0.9V
V
IN
= 28V, SENSE = 0V
V
IN
= 14V, SENSE = –14V
V
IN
= 36V, SENSE = 8V
V
IN
= 0V, SENSE = 28V
V
IN
= –14V, SENSE = 14V
V
IN
= 8V, SENSE = 36V
V
IN
– V
SENSE
, 3V
≤
V
IN
≤
36V, C
GATE
= 3nF
V
SENSE
– V
IN
, 3V
≤
V
IN
≤
36V, C
GATE
= 3nF
●
●
●
●
MIN
3
TYP
MAX
36
UNITS
V
µA
31
60
I
QFH
●
36
61
I
QRL
I
QRH
I
QCL
I
QCH
I
LEAK
21
33
14
26
–10
–10
–10
–10
–10
–10
10
10
–1
30
45
20
35
1
1
1
1
1
1
32
32
PowerPath Controller
V
FR
V
RTO
PowerPath Switch Forward Regulation
Voltage
PowerPath Switch Reverse Turn-Off
Threshold Voltage
mV
mV
4414fc
2
U
W
U
U
W W
W
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
LTC4414
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
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
GATE and STAT Outputs
(Note 4)
–25
190
Apply I
GATE
= 6µA, V
IN
= 12V,
V
SENSE
= 11.9V, Measure V
IN
– V
GATE
Apply I
GATE
= –30µA, V
IN
= 12V,
V
SENSE
= 12.1V, Measure V
SENSE
– V
GATE
V
GS
< –6V, C
GATE
= 17nF (Note 5)
V
GS
> –1.5V, C
GATE
= 17nF (Note 6)
3V
≤
V
IN
≤
36V (Note 7)
12V
≤
V
IN
≤
36V (Note 7)
(Note 8)
(Note 8)
3V
≤
V
IN
≤
36V
3V
≤
V
IN
≤
36V
0.35V
≤
V
CTL
≤
36V
3V
≤
V
IN
≤
36V
●
●
●
●
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
MIN
TYP
MAX
UNITS
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
–7
500
9
0.35
0.92
600
20
µA
µA
V
V
µs
µs
µA
µA
µs
µs
V
8
–1
50
0
1
200
8
51
0.35
0.9
1
3.5
170
5.9
V
µA
mV
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 LTC4414E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC4414I is guaranteed and tested
over the –40° to 125° 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 LTC4414 and operating in
forward regulation.
Note 4:
V
IN
is held at 12V and GATE is forced to 9V. 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) .
4414fc
3
LTC4414
TYPICAL PERFOR A CE CHARACTERISTICS
V
FR
vs Temperature and
Supply Voltage
25
V
IN
= 3V
26
CURRENT (µA)
V
IN
= 28V
V
IN
= 36V
23
V
RTO
(mV)
V
FR
(mV)
21
–50
0
50
100
TEMPERATURE (°C)
4414 G01
V
IN
and SENSE Pin Leakage
vs Temperature
0
9.0
CURRENT (µA)
V
GATE
(V)
I
SENSE
: V
IN
– SENSE = 28V
–1
V
IN –
V
GATE
(V)
I
VIN
: SENSE – V
IN
= 28V
I
GATE
= 0µA
–2
–50
0
50
100
150
4414 G04
TEMPERATURE (°C)
t
G(ON)
vs Temperature
320
C
LOAD
= 15nF
12V
≤
V
IN
≤
36V
10
t
G(ON)
(µs)
t
G(OFF)
(µs)
300
280
–50
0
4
U W
V
RTO
vs Temperature and
Supply Voltage
1.05
Normalized Quiescent Supply
Current vs Temperature
3V
≤
V
IN
≤
36V
1.00
24
V
IN
= 36V
V
IN
= 28V
50
100
150
4414 G02
V
IN
= 3V
150
22
–50
0
0.95
–50
0
50
100
150
4414 G03
TEMPERATURE (°C)
TEMPERATURE (°C)
V
G(ON)
vs Temperature
I
GATE
= 6µA
1.0
V
G(OFF)
vs Temperature and I
GATE
3V
≤
V
IN
≤
36V
V
IN
= 36V
8.5
V
IN
= 10V
0.5
I
GATE
= –60µA
I
GATE
= –30µA
8.0
–50
0
50
100
150
4414 G05
0
–50
0
50
100
150
4414 G06
TEMPERATURE (°C)
TEMPERATURE (°C)
t
G(OFF)
vs Temperature
C
GATE
= 15nF
12V
≤
V
IN
≤
36V
8
50
100
150
4414 G07
6
–50
0
50
100
150
4414 G08
TEMPERATURE (°C)
TEMPERATURE (°C)
4414fc
LTC4414
PI FU CTIO S
STAT (Pin 1):
Open-Drain Output Status Pin. When the
SENSE pin is pulled above the V
IN
pin with an auxiliary
power source by V
RTO
or more, the reverse turn-off
threshold (V
RTO
) is reached. The STAT pin will then go
from an open state to a 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.
CTL (Pin 2):
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 Open-Drain STAT pin ON. 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 Appli-
cations Information). An internal current sink will pull the
CTL pin voltage to ground (logical low) if the pin is open.
GND (Pin 3):
Ground. Provides a power return for all the
internal circuits.
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
battery which also supplies current to the load.
V
IN
(Pin 7):
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.
GATE (Pin 8):
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.
AUXILIARY
SUPPLY
PRIMARY
SUPPLY
7
V
IN
6
SENSE
POWER SOURCE
SELECTOR
POWER
VOLTAGE/CURRENT
REFERENCE
0.5V
A1
LINEAR GATE
DRIVER AND
VOLTAGE CLAMP
GATE
8
V
CC
ON/OFF
2
CTL
3.5µA
+
C1
ANALOG CONTROLLER
ON/OFF
STAT
1
STATUS
OUTPUT
–
3
GND
*DRAIN-SOURCE DIODE OF MOSFET
4414 BD
–
+
+
–
–
+
BLOCK DIAGRA
–
+
W
U
U
U
*
OUTPUT
TO LOAD
4414fc
5
51单片机
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