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LT1579IGN-3#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
1
LT1579
300mA Dual Input Smart
Battery Backup Regulator
Daisy-Chained Control Outputs
FEATURES
The LT
®
1579 is a dual input, single output, low dropout
regulator. This device is designed to provide an
uninterruptible output voltage from two independent input
voltage sources on a priority basis. All of the circuitry
needed to switch smoothly and automatically between
inputs is incorporated.
The LT1579 can supply 300mA of output current from
either input at a dropout voltage of 0.4V. Quiescent current
is 50µA, dropping to 7µA in shutdown. Two comparators
are included to monitor input voltage status. Two addi-
tional status flags indicate which input is supplying power
and provide an early warning against loss of output
regulation when both inputs are low. A secondary select
pin is provided so that the user can force the device to
switch from the primary input to the secondary input.
Internal protection circuitry includes reverse-battery pro-
tection, current limiting, thermal limiting and reverse-
current protection.
The device is available in fixed output voltages of 3V, 3.3V
and 5V, and as an adjustable device with a 1.5V reference
voltage. The LT1579 regulators are available in narrow
16-lead SO and 16-lead SSOP packages with all features,
and in SO-8 with limited features.
DESCRIPTION
U
■
Maintains Output Regulation with Dual Inputs
■
Dropout Voltage: 0.4V
■
Output Current: 300mA
■
50µA Quiescent Current
■
No Protection Diodes Needed
■
Two Low-Battery Comparators
■
Status Flags Aid Power Management
■
Adjustable Output from 1.5V to 20V
■
Fixed Output Voltages: 3V, 3.3V and 5V
■
7µA Quiescent Current in Shutdown
■
Reverse-Battery Protection
■
Reverse Current Protection
■
Remove, Recharge and Replace Batteries Without
Loss of Regulation
5V Dual Battery Supply
Automatic Input Switching
2.7M
1M
2.7M
1M
+
1µF
+
1µF
+
4.7µF
5V
300mA
TO
POWER
MANAGEMENT
0.01µF
IN1
OUT
SS
SHDN
LBO1
LB02
BACKUP
DROPOUT
BIASCOMP
LBI1
IN2
LBI2
GND
LT1579-5
1579 TA01
TIME (ms)
0
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4
8
12
16
1578 TA02
0
5.00
2
6
INPUT CURRENT (mA)
40
80
0
20
60
10
5.05
4.95
4
8
12
218
6
10
14
20
V
IN2
= 10V
I
LOAD
= 50mA
SWITCHOVER
POINT
V
IN1
I
IN1
I
IN2
APPLICATIONS
U
■
Dual Battery Systems
■
Battery Backup Systems
■
Automatic Power Management for
Battery-Operated Systems
TYPICAL APPLICATION
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
2
LT1579
T
JMAX
= 125°C, θ
JA
= 90°C/W
ABSOLUTE MAXIMUM RATINGS
W
WW
U
Power Input Pin Voltage ......................................±20V*
Output Pin Voltage
Fixed Devices............................................. 6.5V, –6V
Adjustable Device ............................................ ±20V*
Output Pin Reverse Current .................................... 5mA
ADJ Pin Voltage..............................................2V, –0.6V
ADJ Pin Current...................................................... 5mA
Control Input Pin Voltage ............................6.5V, –0.6V
Control Input Pin Current ....................................... 5mA
WU
U
PACKAGE
/
O
RDER I FOR ATIO
BIASCOMP Pin Voltage ...............................6.5V, –0.6V
BIASCOMP Pin Current .......................................... 5mA
Logic Flag Output Voltage............................6.5V, –0.6V
Logic Flag Input Current ......................................... 5mA
Output Short-Circuit Duration .......................... Indefinite
Storage Temperature Range ................. – 65°C to 150°C
Operating Junction Temperature Range ....0°C to 125°C
Lead Temperature (Soldering, 10 sec)..................300°C
*For applications requiring input voltage ratings greater than 20V,
consult factory.
ORDER PART
NUMBER
ORDER PART
NUMBER
Consult factory for Industrial and Military grade parts.
SEE APPLICATION INFORMATION SECTION
T
JMAX
= 125°C, θ
JA
= 90°C/W
SEE APPLICATION INFORMATION SECTION
LT1579CS8
S8 PART MARKING
15793
157933
15795
LT1579CS8-3
LT1579CS8-3.3
LT1579CS8-5
ORDER PART
NUMBER
S8 PART MARKING
1579
ORDER PART
NUMBER
SEE APPLICATION INFORMATION SECTION
TOP VIEW
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
V
IN1
V
IN2
SS
SHDN
LBI1
LBI2
GND
GND
OUT
BACKUP
DROPOUT
LBO1
LBO2
BIASCOMP
GND
POWER
INPUTS
CONTROL
INPUTS
LOGIC
OUTPUTS
GN PACKAGE
16-LEAD PLASTIC SSOP
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C, θ
JA
= 95°C/W (GN)
T
JMAX
= 125°C, θ
JA
= 68°C/W (S)
T
JMAX
= 125°C, θ
JA
= 95°C/W (GN)
T
JMAX
= 125°C, θ
JA
= 68°C/W (S)
SEE APPLICATION INFORMATION SECTION
TOP VIEW
GN PACKAGE
16-LEAD PLASTIC SSOP
S PACKAGE
16-LEAD PLASTIC SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
V
IN1
V
IN2
SS
SHDN
LBI1
LBI2
GND
GND
OUT
ADJ
BACKUP
LBO1
LBO2
BIASCOMP
GND
POWER
INPUTS
CONTROL
INPUTS
LOGIC
OUTPUTS
1
2
3
4
8
7
6
5
TOP VIEW
OUT
BACKUP
DROPOUT
BIASCOMP
V
IN1
V
IN2
SHDN
GND
S8 PACKAGE
8-LEAD PLASTIC SO
POWER
INPUTS
CONTROL
INPUT
LOGIC
OUTPUTS
1
2
3
4
8
7
6
5
TOP VIEW
OUT
ADJ
BACKUP
BIASCOMP
V
IN1
V
IN2
SHDN
GND
S8 PACKAGE
8-LEAD PLASTIC SO
POWER
INPUTS
CONTROL
INPUT
LOGIC
OUTPUT
LT1579CGN-3
LT1579CGN-3.3
LT1579CGN-5
LT1579CS-3
LT1579CS-3.3
LT1579CS-5
LT1579CGN
LT1579CS
GN PART MARKING
15793
157933
15795
GN PART MARKING
1579
3
LT1579
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Regulated Output LT1579-3 V
IN1
= V
IN2
= 3.5V, I
LOAD
= 1mA, T
J
= 25°C 2.950 3.000 3.050 V
Voltage (Note 1) 4V < V
IN1
< 20V, 4V < V
IN2
< 20V, 1mA < I
LOAD
< 300mA ● 2.900 3.000 3.100 V
LT1579-3.3 V
IN1
= V
IN2
= 3.8V, I
LOAD
= 1mA, T
J
= 25°C 3.250 3.300 3.350 V
4.3V < V
IN1
< 20V, 4.3V < V
IN2
< 20V, 1mA < I
LOAD
< 300mA ● 3.200 3.300 3.400 V
LT1579-5 V
IN1
= V
IN2
= 5.5V, I
LOAD
= 1mA, T
J
= 25°C 4.925 5.000 5.075 V
6V < V
IN1
< 20V, 6V < V
IN2
< 20V, 1mA < I
LOAD
< 300mA ● 4.850 5.000 5.150 V
Adjust Pin Voltage LT1579 V
IN1
= V
IN2
= 3.2V, I
LOAD
= 1mA, T
J
= 25°C (Note 2) 1.475 1.500 1.525 V
3.7V < V
IN1
< 20V, 3.7V < V
IN2
< 20V, 1mA < I
LOAD
< 300mA ● 1.450 1.500 1.550 V
Line Regulation LT1579-3 ∆V
IN1
= 3.5V to 20V, ∆V
IN2
= 3.5V to 20V, I
LOAD
= 1mA ● 1.5 10 mV
LT1579-3.3 ∆V
IN1
= 3.8V to 20V, ∆V
IN2
= 3.8V to 20V, I
LOAD
= 1mA ● 1.5 10 mV
LT1579-5 ∆V
IN1
= 5.5V to 20V, ∆V
IN2
= 5.5V to 20V, I
LOAD
= 1mA ● 1.5 10 mV
LT1579 ∆V
IN1
= 3.2V to 20V, ∆V
IN2
= 3.2V to 20V, I
LOAD
= 1mA (Note 2) ● 1.5 10 mV
Load Regulation LT1579-3 V
IN1
= V
IN2
= 4V, ∆I
LOAD
= 1mA to 300mA, T
J
= 25°C 3 12 mV
V
IN1
= V
IN2
= 4V, ∆I
LOAD
= 1mA to 300mA ● 25 mV
LT1579-3.3 V
IN1
= V
IN2
= 4.3V, ∆I
LOAD
= 1mA to 300mA, T
J
= 25°C 3 12 mV
V
IN1
= V
IN2
= 4.3V, ∆I
LOAD
= 1mA to 300mA ● 25 mV
LT1579-5 V
IN1
= V
IN2
= 6V, ∆I
LOAD
= 1mA to 300mA, T
J
= 25°C 5 15 mV
V
IN1
= V
IN2
= 6V, ∆I
LOAD
= 1mA to 300mA ● 35 mV
LT1579 V
IN1
= V
IN2
= 3.7V, ∆I
LOAD
= 1mA to 300mA, T
J
= 25°C (Note 2) 2 10 mV
V
IN1
= V
IN2
= 3.7V, ∆I
LOAD
= 1mA to 300mA ● 20 mV
Dropout Voltage I
LOAD
= 10mA, T
J
= 25°C 0.10 0.28 V
(Notes 3, 4) I
LOAD
= 10mA ● 0.39 V
V
IN1
= V
IN2
=
I
LOAD
= 50mA, T
J
= 25°C 0.18 0.35 V
V
OUT(NOMINAL)
I
LOAD
= 50mA ● 0.45 V
I
LOAD
= 150mA, T
J
= 25°C 0.25 0.47 V
I
LOAD
= 150mA ● 0.60 V
I
LOAD
= 300mA, T
J
= 25°C 0.34 0.60 V
I
LOAD
= 300mA ● 0.75 V
Ground Pin Current I
LOAD
= 0mA, T
J
= 25°C 50 100 µA
(Note 5) I
LOAD
= 0mA ● 400 µA
V
IN1
= V
IN2
=
I
LOAD
= 1mA, T
J
= 25°C 100 200 µA
V
OUT(NOMINAL)
+ 1V
I
LOAD
= 1mA ● 500 µA
I
LOAD
= 50mA ● 0.7 1.5 mA
I
LOAD
= 150mA ● 24 mA
I
LOAD
= 300mA ● 5.8 12 mA
Standby Current I
VIN2
: V
IN1
= 20V, V
IN2
= V
OUT(NOMINAL)
+ 0.5V, V
SS
= Open (HI) ● 3.3 7.0 µA
(Note 6) I
LOAD
= 0mA I
VIN1
: V
IN1
= V
OUT(NOMINAL)
+ 0.5V, V
IN2
= 20V, V
SS
= 0V ● 2.0 7.0 µA
Shutdown Threshold V
OUT
= Off to On ● 0.9 2.8 V
V
OUT
= On to Off ● 0.25 0.75 V
Shutdown Pin Current V
SHDN
= 0V ● 1.3 5 µA
(Note 7)
Quiescent Current in I
VIN1
: V
IN1
= 20V, V
IN2
= 6V, V
SHDN
= 0V ● 512 µA
Shutdown (Note 9) I
VIN2
: V
IN1
= 6V, V
IN2
= 20V, V
SHDN
= 0V ● 512 µA
I
SRC
: V
IN1
= V
IN2
= 20V, V
SHDN
= 0V 3 µA
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LT1579IGN-3#PBF

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Manufacturer:
Analog Devices / Linear Technology
Description:
LDO Voltage Regulators 300mA Dual Input Smart LDO 3V
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