1
LT1529
LT1529-3.3/LT1529-5
3A Low Dropout Regulators
with Micropower
Quiescent Current
and Shutdown
The LT
1529/LT1529-3.3/LT1529-5 are 3A low dropout
regulators with micropower quiescent current and shut-
down. The devices are capable of supplying 3A of output
current with a dropout voltage of 0.6V. Designed for use
in battery-powered systems, the low quiescent current,
50
A operating and 16
A in shutdown, make them an
ideal choice. The quiescent current is well controlled; it
does not rise in dropout as it does with many other low
dropout PNP regulators.
Other features of the LT1529 /LT1529-3.3/LT1529-5 in-
clude the ability to operate with small output capacitors.
They are stable with only 3.3
F on the output while most
older devices require between 10
F and 100
F for stabil-
ity. Small ceramic capacitors can be used, enhancing
manufacturabiltiy. Also the input may be connected to
voltages lower than the output voltage, including negative
voltages, without reverse current flow from output to
input. This makes the LT1529/LT1529-3.3/LT1529-5 ideal
for backup power situations where the output is held high
and the input is at ground or reversed. Under these
conditions, only 16
A will flow from the OUTPUT pin to
ground. The devices are available in 5-lead TO-220 and
5-lead DD packages.
s
Dropout Voltage: 0.6V at I
OUT
= 3A
s
Output Current: 3A
s
Quiescent Current: 50
A
s
No Protection Diodes Needed
s
Adjustable Output from 3.8V to 14V
s
3.3V and 5V Fixed Output Voltages
s
Controlled Quiescent Current in Dropout
s
Shutdown I
Q
= 16
A
s
Stable with 3.3
F Output Capacitor
s
Reverse Battery Protection
s
No Reverse Current
s
Thermal Limiting
OUTPUT CURRENT (A)
0
0
DROPOUT VOLTAGE (V)
0.1
0.2
0.3
0.4
0.6
0.5
1.0
1.5
2.0
LT1529 TA02
2.5
3.0
0.5
Dropout Voltage
5V Supply with Shutdown
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
High Efficiency Regulator
s
Regulator for Battery-Powered Systems
s
Post Regulator for Switching Supplies
s
5V to 3.3V Logic Regulator
+
V
IN
V
IN
> 5.5V
3.3
F
SOLID
TANT
5V
3A
1
2
3
LT1529 TA01
5
4
OUTPUT
SENSE
LT1529-5
SHDN
GND
V
SHDN
(PIN 4)
< 0.25
> 2.8
NC
OUTPUT
OFF
ON
ON
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LT1529
LT1529-3.3/LT1529-5
Output Short-Circuit Duration ......................... Indefinite
Storage Temperature Range ................ 65
C to 150
C
Operating Junction Temperature Range
Commercial .......................................... 0
C to 125
C
Industrial ......................................... 45
C to 125
C
Lead Temperature (Soldering, 10 sec).................. 300
C
*
For applications requiring input voltage ratings greater than 15V, contact
the factory.
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
Input Voltage ......................................................
15V*
OUTPUT Pin Reverse Current .............................. 10mA
SENSE Pin Current .............................................. 10mA
ADJ Pin Current ................................................... 10mA
SHDN Pin Input Voltage (Note 2) .............. 6.5V, 0.6V
SHDN Pin Input Current (Note 2) .......................... 5mA
W
U
U
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
LT1529CQ
LT1529CQ-3.3
LT1529CQ-5
LT1529IQ
LT1529IQ-3.3
LT1529IQ-5
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
ORDER PART
NUMBER
LT1529CT
LT1529CT-3.3
LT1529CT-5
LT1529IT
LT1529IT-3.3
LT1529IT-5
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
Consult factory for Military grade parts.
T
JMAX
= 125
C,
JA
30
C/ W
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Regulated Output Voltage
LT1529-3.3
V
IN
= 3.8V, I
OUT
= 1mA, T
J
= 25
C
3.250
3.300
3.350
V
(Note 4)
4.3V < V
IN
< 15V, 1mA < I
OUT
< 3A
q
3.200
3.300
3.400
V
LT1529-5
V
IN
= 5.5V, I
OUT
= 1mA, T
J
= 25
C
4.925
5.000
5.075
V
6V < V
IN
< 15V, 1mA < I
OUT
< 3A
q
4.850
5.000
5.150
V
LT1529 (Note 5)
V
IN
= 4.3V, I
OUT
= 1mA, T
J
= 25
C
3.695
3.750
3.805
V
4.8V < V
IN
< 15V, 1mA < I
OUT
< 3A
q
3.640
3.750
3.860
V
Line Regulation
LT1529-3.3
V
IN
= 3.8V to 15V, I
OUT
= 1mA
q
1.5
10
mV
LT1529-5
V
IN
= 5.5V to 15V, I
OUT
= 1mA
q
1.5
10
mV
LT1529 (Note 5)
V
IN
= 4.3V to 15V, I
OUT
= 1mA
q
1.5
10
mV
Load Regulation
LT1529-3.3
I
LOAD
= 1mA to 3A, V
IN
= 4.3V, T
J
= 25
C
5
20
mV
I
LOAD
= 1mA to 3A, V
IN
= 4.3V
q
12
30
mV
LT1529-5
I
LOAD
= 1mA to 3A, V
IN
= 6V, T
J
= 25
C
5
20
mV
I
LOAD
= 1mA to 3A, V
IN
= 6V
q
12
30
mV
LT1529 (Note 5)
I
LOAD
= 1mA to 3A, V
IN
= 4.8V, T
J
= 25
C
5
20
mV
I
LOAD
= 1mA to 3A, V
IN
= 4.8V
q
12
30
mV
Dropout Voltage
I
LOAD
= 10mA, T
J
= 25
C
110
180
mV
(Note 6)
I
LOAD
= 10mA
q
250
mV
I
LOAD
= 100mA, T
J
= 25
C
200
300
mV
I
LOAD
= 100mA
q
400
mV
ELECTRICAL C
C
HARA TERISTICS
V
IN
SHDN
GND
SENSE/ADJ*
OUTPUT
Q PACKAGE
5-LEAD PLASTIC DD PAK
TAB IS
GND
FRONT VIEW
5
4
3
2
1
T PACKAGE
5-LEAD PLASTIC TO-220
FRONT VIEW
TAB IS
GND
5
4
3
2
1
V
IN
SHDN
GND
SENSE/ADJ*
OUTPUT
(Note 1)
T
JMAX
= 125
C,
JA
50
C/ W
The
q
denotes specifications which apply over the operating temperature range, otherwise specificatons are at T
A
= 25
C. (Note 3)
3
LT1529
LT1529-3.3/LT1529-5
ELECTRICAL C
C
HARA TERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Dropout Voltage
I
LOAD
= 700mA, T
J
= 25
C
320
430
mV
(Note 6)
I
LOAD
= 700mA
q
550
mV
I
LOAD
= 1.5A, T
J
= 25
C
430
550
mV
I
LOAD
= 1.5A
q
700
mV
I
LOAD
= 3A, T
J
= 25
C
600
750
mV
I
LOAD
= 3A
q
950
mV
GND Pin Current
I
LOAD
= 0mA, T
J
= 25
C
50
100
A
(Note 7)
I
LOAD
= 0mA, T
J
= 125
C (Note 8)
400
A
I
LOAD
= 100mA, T
J
= 25
C
0.6
1.0
mA
I
LOAD
= 100mA, T
J
= 125
C (Note 8)
1.0
mA
I
LOAD
= 700mA
q
5.5
12
mA
I
LOAD
= 1.5A
q
20
40
mA
I
LOAD
= 3A
q
80
160
mA
ADJ Pin Bias Current (Notes 5, 9)
T
J
= 25
C
150
300
nA
Shutdown Threshold
V
OUT
= Off to On
q
1.20
2.8
V
V
OUT
= On to Off
q
0.25
0.75
V
SHDN Pin Current (Note 10)
V
SHDN
= 0V
q
4.5
10
A
Quiescent Current in Shutdown
V
IN
= V
OUT
(Nominal) + 1V, V
SHDN
= 0V
q
15
30
A
(Note 11)
Ripple Rejection
V
IN
V
OUT
= 1V (Avg), V
RIPPLE
= 0.5V
P-P
,
50
62
dB
f
RIPPLE
= 120Hz, I
LOAD
= 1.5A
Current Limit
V
IN
V
OUT
= 7V, T
J
= 25
C
5
A
V
IN
= V
OUT
(Nominal) + 1.5V,
V
OUT
= 0.1V
q
3.2
4.7
A
Input Reverse Leakage Current
V
IN
= 15V, V
OUT
= 0V
q
1.0
mA
Reverse Output Current (Note 12)
LT1529-3.3
V
OUT
= 3.3V, V
IN
= 0V
16
A
LT1529-5
V
OUT
= 5V, V
IN
= 0V
16
A
LT1529 (Note 6)
V
OUT
= 3.8V, V
IN
= 0V
16
A
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The SHDN pin input voltage rating is required for a low impedance
source. Internal protection devices connected to the SHDN pin will turn on
and clamp the pin to approximately 7V or 0.6V. This range allows the use
of 5V logic devices to drive the pin directly. For high impedance sources or
logic running on supply voltages greater than 5.5V, the maximum current
driven into the SHDN pin must be limited to less than 5mA.
Note 3: The device is tested under pulse load conditions such that T
J
= T
A
.
Note 4: Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply for
all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current the input voltage
range must be limited.
Note 5: The LT1529 is tested and specified with the ADJ pin connected to
the OUTPUT pin.
Note 6: Dropout voltage is the minimum input/output voltage required to
maintain regulation at the specified output current. In dropout the output
voltage will be equal to (V
IN
V
DROPOUT
).
Note 7: GND pin current is tested with V
IN
= V
OUT
(nominal) and a current
source load. This means that the device is tested while operating in its
dropout region. This is the worst-case GND pin current. The GND pin
current will decrease slightly at higher input voltages.
Note 8: GND pin current will rise at T
J
> 75
C. This is due to internal
circuitry designed to compensate for leakage currents in the output
transistor at high temperatures. This allows quiescent current to be
minimized at lower temperatures, yet maintain output regulation at high
temperatures with light loads. See quiescent current curve in typical
performance characteristics.
Note 9: ADJ pin bias current flows into the ADJ pin.
Note 10: SHDN pin current at V
SHDN
= 0V flows out of the SHDN pin.
Note 11: Quiescent current in shutdown is equal to the sum total of the
SHDN pin current (5
A) and the GND pin current (10
A).
Note 12: Reverse output current is tested with the V
IN
pin grounded and
the OUTPUT pin forced to the rated output voltage. This current flows into
the OUTPUT pin and out of the GND pin.
The
q
denotes specifications which apply over the operating temperature range, otherwise specificatons are at T
A
= 25
C. (Note 3)
4
LT1529
LT1529-3.3/LT1529-5
Quiescent Current
C
C
HARA TERISTICS
U
W
A
TYPICAL PERFOR
CE
TEMPERATURE (
C)
50
0
QUIESCENT CURRENT (
A)
100
250
0
50
75
LT1529 G03
50
200
150
25
25
100
125
V
IN
= 6V
R
L
=
V
SHDN
= OPEN
V
SHDN
= 0V
Guaranteed Dropout Voltage
Dropout Voltage
TEMPERATURE (
C)
50
DROPOUT VOLTAGE (V)
0.7
A
B
C
D
E
F
25
LT1529 G02
0.4
0.2
25
0
50
0.1
0
0.8
0.6
0.5
0.3
75
100
125
A: I
LOAD
= 3A
B: I
LOAD
= 1.5A
C: I
LOAD
= 700mA
D: I
LOAD
= 300mA
E: I
LOAD
= 100mA
F: I
LOAD
= 10mA
LT1529
Quiescent Current
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (
A)
150
200
250
8
LT1529 G06
100
50
125
175
225
75
25
0
2
4
6
1
9
3
5
7
10
I
LOAD
= 0
R
L
=
V
OUT
= V
ADJ
V
SHDN
= OPEN (HIGH)
V
SHDN
= 0V
LT1529-3.3
Quiescent Current
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (
A)
150
200
250
8
LT1529 G04
100
50
125
175
225
75
25
0
2
4
6
1
9
3
5
7
10
I
LOAD
= 0
R
L
=
V
SHDN
= OPEN (HIGH)
V
SHDN
= 0V
LT1529-5
Quiescent Current
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (
A)
150
200
250
8
LT1529 G05
100
50
125
175
225
75
25
0
2
4
6
1
9
3
5
7
10
I
LOAD
= 0
R
L
=
V
SHDN
= OPEN (HIGH)
V
SHDN
= 0V
LT1529-3.3
Output Voltage
TEMPERATURE (
C)
50
OUTPUT VOLTAGE (V)
3.375
25
LT1529 G07
3.300
3.250
25
0
50
3.225
3.200
3.400
3.350
3.325
3.275
75
100
125
I
LOAD
= 1mA
LT1529-5
Output Voltage
TEMPERATURE (C)
50
OUTPUT VOLTAGE (V)
5.075
25
LT1529 G08
5.000
4.950
25
0
50
4.925
4.900
5.100
5.050
5.025
4.975
75
100
125
I
LOAD
= 1mA
LT1529
ADJ Pin Voltage
TEMPERATURE (
C)
50
ADJ PIN VOLTAGE (V)
3.825
25
LT1529 G09
3.750
3.700
25
0
50
3.675
3.650
3.850
3.800
3.775
3.725
75
100
125
I
LOAD
= 1mA
OUTPUT CURRENT (A)
0
0
DROPOUT VOLTAGE (V)
0.2
0.3
0.4
0.5
0.6
0.7
0.5
1.0
1.5
2.0
LT1529 G01
2.5
0.8
0.9
1.0
0.1
3.0
= TEST POINT
5
LT1529
LT1529-3.3/LT1529-5
C
C
HARA TERISTICS
U
W
A
TYPICAL PERFOR
CE
LT1529-3.3
GND Pin Current
LT1529-5
GND Pin Current
LT1529
GND Pin Current
LT1529-5
GND Pin Current
GND Pin Current
SHDN Pin Threshold
(Off-to-On)
LT1529-3.3
GND Pin Current
LT1529
GND Pin Current
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
60
80
100
8
LT1529 G15
40
20
50
70
90
30
10
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
ADJ
*FOR V
OUT
= 3.75V
R
LOAD
= 1.25
I
LOAD
= 3A*
R
LOAD
= 2.5
I
LOAD
= 1.5A*
R
LOAD
= 5.3
I
LOAD
= 700mA*
OUTPUT CURRENT (A)
0
0
GND PIN CURRENT (mA)
20
30
40
50
60
70
0.5
1.0
1.5
2.0
LT1529 G16
2.5
80
90
100
10
3.0
V
IN
= 3.75V (LT1529)
V
IN
= 3.3V (LT1529-3.3)
V
IN
= 5V (LT1529-5)
DEVICE IS OPERATING
IN DROPOUT
T
J
= 125
C
T
J
= 50
C
T
J
= 25
C
SHDN Pin Threshold
(On-to-Off)
TEMPERATURE (
C)
50
0
SHDN THRESHOLD (V)
0.2
0.6
0.8
1.0
2.0
1.4
0
50
75
LT1529 G17
0.4
1.6
1.8
1.2
25
25
100
125
I
LOAD
= 1mA
TEMPERATURE (
C)
50
0
SHDN THRESHOLD (V)
0.2
0.6
0.8
1.0
2.0
1.4
0
50
75
LT1529 G18
0.4
1.6
1.8
1.2
25
25
100
125
I
LOAD
= 3A
I
LOAD
= 1mA
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
3.0
4.0
5.0
8
LT1529 G10
2.0
1.0
2.5
3.5
4.5
1.5
0.5
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
SENSE
*FOR V
OUT
= 3.3V
R
LOAD
= 6.6
I
LOAD
= 500mA*
R
LOAD
= 11
I
LOAD
= 300mA*
R
LOAD
= 33
I
LOAD
= 100mA*
R
LOAD
= 330
I
LOAD
= 10mA*
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
60
80
100
8
LT1529 G13
40
20
50
70
90
30
10
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
SENSE
R
LOAD
= 1.1
I
LOAD
= 3A*
R
LOAD
= 2.2
I
LOAD
= 1.5A*
R
LOAD
= 4.7
I
LOAD
= 700mA*
*FOR V
OUT
= 3.3V
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
60
80
100
8
LT1529 G14
40
20
50
70
90
30
10
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
SENSE
*FOR V
OUT
= 5V
R
LOAD
= 1.7
I
LOAD
= 3A*
R
LOAD
= 3.3
I
LOAD
= 1.5A*
R
LOAD
= 7.1
I
LOAD
= 700mA*
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
3.0
4.0
5.0
8
LT1529 G11
2.0
1.0
2.5
3.5
4.5
1.5
0.5
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
SENSE
*FOR V
OUT
= 5V
R
LOAD
= 10
I
LOAD
= 500mA*
R
LOAD
= 16.6
I
LOAD
= 300mA*
R
LOAD
= 500
I
LOAD
= 10mA*
R
LOAD
= 50
I
LOAD
= 100mA*
INPUT VOLTAGE (V)
0
GND PIN CURRENT (mA)
3.0
4.0
5.0
8
LT1529 G12
2.0
1.0
2.5
3.5
4.5
1.5
0.5
0
2
4
6
1
9
3
5
7
10
T
J
= 25
C
V
OUT
= V
ADJ
*FOR V
OUT
=
3.75V
R
LOAD
= 7.5
I
LOAD
= 500mA*
R
LOAD
= 12.5
I
LOAD
= 300mA*
R
LOAD
= 375
I
LOAD
= 10mA*
R
LOAD
= 38
I
LOAD
= 100mA*
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