LTC4420
18V Dual Input Micropower
PowerPath Prioritizer with
Backup Supply Monitoring
FEATURES
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DESCRIPTION
The
LTC
®
4420
is a dual input monolithic PowerPath™
prioritizer, with low operating current, that provides
backup switchover for keeping critical circuitry alive dur-
ing brownout and power loss conditions. Unlike diode-OR
products, little current is drawn from the inactive supply
even if its voltage is greater than the active supply.
Internal 2Ω, current limited PMOS switches provide
power path selection from a primary input (V1) or a backup
input (V2) to the output. Two adjustable voltage monitors
set via external resistive dividers provide flexibility in set-
ting V1 to V2 switchover and V2 undervoltage thresholds.
V1 is monitored continuously while V2 supply monitoring
includes controllable low duty cycle UV monitoring. When
primary input V1 drops, the ADJ monitor causes OUT to
be switched to V2. When V2 drops, it is disconnected from
OUT if
V2DIS
is low. Fast non-overlap switchover circuitry
prevents reverse and cross conduction while minimizing
output droop.
Auxiliary voltage monitor CMP1 provides flexible voltage
monitoring and output V2OK provides V2 undervoltage
status. Freshness seal mode prevents V2 battery discharge
during storage or shipment.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath and ThinSOT are trademarks of Analog Devices, Inc. All other trademarks are the
property of their respective owners.
Selects Highest Priority Valid Supply from Two
Inputs
Wide 1.8V to 18V Operating Range
Internal Dual 2Ω, 0.5A Switches
Low 3.6µA Operating Current
Low 320nA V2 Current When V1 Connected to OUT
Blocks Reverse and Cross Conduction Currents
Reverse Supply Protection to –15V
Built-In V2 Test with Optional V2 Disconnect
V2 Freshness Seal/Ship Mode
±1.5% Accurate Adjustable Switchover Threshold
±2.3% Accurate V2 Monitor and Comparator
Overcurrent and Thermal Protection
Thermally Enhanced 12-Pin 3mm
×
3mm
DFN and 12-Lead Exposed Pad MSOP Packages
APPLICATIONS
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Low Power Battery Backup
Portable Equipment
Point-of-Sale (POS) Equipment
TYPICAL APPLICATION
5V WALL
ADAPTER
10µF
237k
CMP1
121k
V2OK
V2OK
Typical Switchover Waveforms
V1
1M
ADJ CMPOUT1
OUT
1M
V1UV
V2
2V/DIV
V1
2V/DIV
SWITCHOVER
THRESHOLD
V2 UNDERVOLTAGE
AND DISCONNECT
1M
OUT
V2 MONITORING
INTERVAL
LTC4420
V2
V2DIS
+
7.4V
Li-Ion
4.02M
V2UV V2TEST
280k
GNDSW
GND
TYPICAL VALUES:
SWITCHOVER THRESHOLD: V1 < 4V (V1 FALLING)
V1UV
THRESHOLD: V1 < 4.4V (V1 FALLING)
4420 TA01a
V2OK THRESHOLD: V2 < 6V (V2 FALLING)
C
OUT
= 10µF
I
LOAD
= 100mA
20ms/DIV
OUT
4420 TA01b
4420fa
For more information
www.linear.com/LTC4420
1
LTC4420
ABSOLUTE MAXIMUM RATINGS
Terminal Voltages
V1, V2 ......................................................–15V to 24V
OUT ....................................................... –0.3V to 24V
OUT – V2 .................................................–24V to 39V
OUT – V1 .................................................–24V to 39V
Input Voltages
ADJ, CMP1, V2UV, V2TEST,
V2DIS
(Note 3) ................................................ –0.3V to 24V
Output Voltages
CMPOUT1, GNDSW, V2OK (Note 3) ...... –0.3V to 24V
(Notes 1, 2)
Pin Currents (Note 2)
ADJ, CMP1, V2UV, CMPOUT1, GNDSW .............–1mA
V2TEST,
V2DIS,
V2OK ......................................–1mA
Operating Ambient Temperature Range
LTC4420C ................................................ 0°C to 70°C
LTC4420I .............................................–40°C to 85°C
Junction Temperature (Notes 4, 5)........................ 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MSOP Package ................................................. 300°C
PIN CONFIGURATION
TOP VIEW
V1
V2TEST
CMP1
ADJ
GND
CMPOUT1
1
2
3
4
5
6
13
GND
12 V2
11
V2DIS
10 V2UV
9 OUT
8 V2OK
7 GNDSW
V1
V2TEST
CMP1
ADJ
GND
CMPOUT1
1
2
3
4
5
6
TOP VIEW
12
11
10
9
8
7
V2
V2DIS
V2UV
OUT
V2OK
GNDSW
13
GND
DD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
MSE PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 40°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC4420CDD#PBF
LTC4420IDD#PBF
LTC4420CMSE#PBF
LTC4420IMSE#PBF
TAPE AND REEL
LTC4420CDD#TRPBF
LTC4420IDD#TRPBF
LTC4420CMSE#TRPBF
LTC4420IMSE#TRPBF
http://www.linear.com/product/LTC4420#orderinfo
PART MARKING*
LGMR
LGMR
4420
4420
PACKAGE DESCRIPTION
12-Lead (3mm
×
3mm) Plastic DFN
12-Lead (3mm
×
3mm) Plastic DFN
12-Lead Plastic Exposed Pad MSOP
12-Lead Plastic Exposed Pad MSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified 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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V1 = 3.6V, V2 = 3.6V unless otherwise noted.
SYMBOL
V1, V2
I
V1
PARAMETER
Operating Voltage Range
V1 Current, V1 Powering OUT
V1 Current, V2 Powering OUT
I
OUT
= 0, V1 = 8.4V, V2 = 3.6V
V1 = 8.4V, V2 = 3.6V
CONDITIONS
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ELECTRICAL CHARACTERISTICS
MIN
1.8
TYP
MAX
18
UNITS
V
µA
nA
4420fa
Supply Voltage and Currents
3.6
500
6.3
800
2
For more information
www.linear.com/LTC4420
LTC4420
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V1 = 3.6V, V2 = 3.6V unless otherwise noted.
SYMBOL
I
V2
R
ON
t
VALID(V1)
V
THA
V
HYSTA
V
THC
V
HYSTC
t
PDA
t
PDC
I
LIM
V
REV
t
SWITCH
V2 Monitoring
t
MONL
t
MONS
t
LTEST
t
HV2T
t
LV2T
V
OL
V
OH
I
OH
V
IL
V
IH
I
V2X(IN,Z)
I
PU(V2OK)
I
LEAK
Longest Possible V2UV Monitor Duration
Shortest Possible V2UV Monitor Duration
Time Between V2UV Monitoring Events
Minimum Allowed V2TEST High Time
Minimum Allowed V2TEST Low Time
V2TEST ≥ V
IH
V2TEST ≥ V
IH
V2TEST ≥ V
IH
V2TEST Driven Externally
V2TEST Driven Externally
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ELECTRICAL CHARACTERISTICS
PARAMETER
V2 Current, V2 Powering OUT
V2 Current, V1 Powering OUT
V2 Current in Freshness Seal Mode
Switch Resistance
Input Qualification Time
ADJ Threshold
ADJ Comparator Hysteresis
CMP1, V2UV Threshold
CMP1, V2UV Comparator Hysteresis
ADJ Comparator Falling Response Time
CMP1, V2UV Comparator Response Times
Output Current Limit
Reverse Comparator Threshold
Break-Before-Make Switchover Time
CONDITIONS
I
OUT
= 0, V1 = 3.6V, V2 = 8.4V
V1 = 3.6V, V2 = 8.4V
V1 = GND, V2 = 5V
V1 = V2 = 5V, I
OUT
= –100mA
V1 Rising, ADJ Rising
ADJ Falling
ADJ Rising
CMP1, V2UV Falling
CMP1, V2UV Rising
10% Overdrive
20% Overdrive
V1, V2 = 8.4V
(V1, V2) – V
OUT
for Power Path Turn-On
V1 = V2 = 5V, I
OUT
= –100mA
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MIN
TYP
3.3
320
120
MAX
6
650
220
5
94
1.062
70
0.396
12.5
12
65
1.6
75
5
168
3
180
UNITS
µA
nA
nA
Ω
ms
V
mV
V
mV
µs
µs
A
mV
µs
ms
ms
s
ms
ms
1
34
1.032
30
0.378
7.5
4
2
64
1.047
50
0.387
10
7.3
30
Input Comparators
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Power Path Function
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0.5
25
1
88
1
80
10
10
1.1
50
2.5
128
2
132
I/O Specifications
Output Voltage Low, CMPOUT1, GNDSW and V2OK I = 100µA
I = 1mA
V2OK Output High Voltage
V2OK, GNDSW, CMPOUT1 Output High Leakage
V2DIS,
V2TEST Input Low Voltage
V2DIS,
V2TEST Input High Voltage
V2DIS,
V2TEST Allowable Leakage in Open State
V2OK Pull-Up Current
ADJ, CMP1, V2UV Leakage Current
V2 = 5V, ADJ = 0V, V2OK = 0V
ADJ, CMP1, V2UV = 0V, 1.5V
I = –1µA, V2 = 5V
CMPOUT1, GNDSW, V2OK = 18V
V1 = V2 = 5V
V1 = V2 = 5V
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15
120
1.05
1.65
±50
0.9
50
250
2.3
±150
0.2
0.5
mV
mV
V
nA
V
V
µA
µA
nA
–2.7
–5
±1
–8
±5
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:
All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 3:
These pins can be tied to voltages down to –5V through a resistor
that limits the current to less than –1mA.
Note 4:
The LTC4420 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 5:
The LTC4420 is tested under pulsed load conditions such that
T
J
≈ T
A
. The junction temperature (T
J
in °C) is calculated from the ambient
temperature (T
A
in °C) and power dissipation (P
D
in Watts) according to
the formula:
T
J
= T
A
+ (P
D
•
θ
JA
)
4420fa
For more information
www.linear.com/LTC4420
3
LTC4420
(T
A
= 25°C, V1 = V2 = 3.6V unless otherwise indicated)
V1 Current, V1 Powers OUT
(I
OUT
= 0)
V1 = 1.8V
V1 = 3.6V
V1 ≥ 6V
V2 CURRENT (µA)
4.0
TYPICAL PERFORMANCE CHARACTERISTICS
4.5
V2 Current, V2 Powers OUT
(I
OUT
= 0)
V2 = 1.8V
V2 = 3.6V
V2 ≥ 6V
V2 CURRENT (nA)
450
400
350
300
250
200
2.5
–50
150
V2 Current, V1 Powers Out
V1 = V2
4.0
V1 CURRENT (µA)
3.5
3.5
3.0
3.0
–40°C
25°C
90°C
0
5
10
15
V2 VOLTAGE (V)
20
4420 G03
2.5
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
–25
0
25
50
75
TEMPERATURE (°C)
100
125
4420 G01
4420 G02
V1 Current, V2 Powers Out
550
V1 = V2
250
Open-Drain (CMPOUT1, GNDSW,
V2OK) V
OL
vs Pull-Down Current
Normalized CMP1 and
V2UV Falling Thresholds vs
Temperature
1.010
500
V1 CURRENT (nA)
200
1.005
NORMALIZED V
THC
V
OL
(mV)
450
150
1.000
400
–40°C
25°C
90°C
0
5
10
15
V2 VOLTAGE (V)
20
4420 G04
100
350
50
0.995
300
0
0
0.5
1
1.5
PULL-DOWN CURRENT (mA)
2
4420 G05
0.990
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
4420 G06
Normalized Falling ADJ
Threshold vs Temperature
1.010
70
ADJ Hysteresis vs Temperature
3.0
ADJ Leakage vs Temperature
V
ADJ
= 0V, 1.5V
ADJ HYSTERESIS (mV)
1.005
NORMALIZED V
THA
60
ADJ LEAKAGE (nA)
–25
0
25
50
75
TEMPERATURE (°C)
100
125
2.5
2.0
1.000
50
1.5
0.995
40
1.0
0.990
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
30
–50
0.5
–50
–25
4420 G07
4420 G08
0
25
50
75
TEMPERATURE (°C)
100
125
4420 G09
4
4420fa
For more information
www.linear.com/LTC4420
LTC4420
(T
A
= 25°C, V1 = V2 = 3.6V unless otherwise indicated)
Output Current Limit vs Temperature
1.40
1.30
CURRENT LIMIT (A)
1.20
I
OUT
(A)
1.10
1.00
0.90
0.80
–50
3.0
2.5
2.0
1.5
1.0
0.5
0
TYPICAL PERFORMANCE CHARACTERISTICS
Output Current I
OUT
Response for
Different Shorting Impedances
1.2Ω
2.2Ω
3.3Ω
3.9Ω
5Ω
I
OUT
(A)
1.2
1.0
0.8
0.6
0.4
0.2
0
4419 G11
I
OUT
vs V
OUT
for Different Input
Supply Voltages
FOLDBACK
CURRENT
LIMIT
OHMIC
V
IN
= 1.8V
V
IN
= 3.6V
V
IN
= 5V
–25
0
25
50
75
TEMPERATURE (°C)
100
125
40µs/DIV
0
1
4420 G10
2
3
V
OUT
(V)
4
5
4419 G12
5
Switch R
ON
vs Temperature
5V
3.6V
2V
V2 CURRENT (nA)
250
Freshness Seal Current vs
V2 Voltage and Temperature
1.8V
3.6V
5V
≥6V
V1 = 0V
4
R
ON
(Ω)
200
150
3
100
2
50
1
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
0
–50
–25
4419 G13
0
25
50
TEMPERATURE (°C)
75
100
4420 G14
Switchover from a Higher to a
Lower Voltage
V1
OUT
2V/DIV
V2
CONNECT TO V2
C
OUT
= 10µF
I
OUT
= 200mA
V2
DISCONNECT FROM V1
V1
2V/DIV
I
OUT
0.5A/DIV
4419 G15
Output Voltage and Current
Waveforms During Switchover
10V
6V
OUT
C
OUT
= 10µF
C1= C2 = 10µF
I
LOAD
= 50mA
V2
5V/DIV
V1
10V/DIV
V1 Reverse Voltage Blocking
with V2 Powering Out
6V
10V
–10V
I
OUT
0.5A/DIV
20ms/DIV
I
LOAD
= 50mA
4420 G17
3ms/DIV
10µs/DIV
4420 G16
4420fa
For more information
www.linear.com/LTC4420
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