LT1529
LT1529-3.3/LT1529-5
3A Low Dropout Regulators
with Micropower
Quiescent Current
and Shutdown
DESCRIPTIO
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,
50µA operating and 16µA 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 3.3µF on the output while most
older devices require between 10µF and 100µF 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 16µA will flow from the OUTPUT pin to
ground. The devices are available in 5-lead TO-220 and
5-lead DD packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
Dropout Voltage: 0.6V at I
OUT
= 3A
Output Current: 3A
Quiescent Current: 50µA
No Protection Diodes Needed
Adjustable Output from 3.8V to 14V
3.3V and 5V Fixed Output Voltages
Controlled Quiescent Current in Dropout
Shutdown I
Q
= 16µA
Stable with 3.3µF Output Capacitor
Reverse Battery Protection
No Reverse Current
Thermal Limiting
APPLICATIO S
s
s
s
s
High Efficiency Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies
5V to 3.3V Logic Regulator
TYPICAL APPLICATIO
5
V
IN
> 5.5V
0.6
5V Supply with Shutdown
V
IN
OUTPUT
1
0.5
LT1529-5
4
SHDN SENSE
GND
3
2
+
3.3µF
SOLID
TANT
5V
3A
DROPOUT VOLTAGE (V)
0.4
0.3
0.2
0.1
V
SHDN
(PIN 4)
< 0.25
> 2.8
NC
OUTPUT
OFF
ON
ON
0
LT1529 • TA01
0
0.5
U
U
U
Dropout Voltage
1.0
1.5
2.0
OUTPUT CURRENT (A)
2.5
3.0
LT1529 • TA02
1
LT1529
LT1529-3.3/LT1529-5
ABSOLUTE
AXI U
RATI GS
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
PACKAGE/ORDER I FOR ATIO
FRONT VIEW
5
4
3
2
1
V
IN
SHDN
GND
SENSE/ADJ*
OUTPUT
ORDER PART
NUMBER
LT1529CQ
LT1529CQ-3.3
LT1529CQ-5
LT1529IQ
LT1529IQ-3.3
LT1529IQ-5
TAB IS
GND
TAB IS
GND
Q PACKAGE
5-LEAD PLASTIC DD PAK
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
T
JMAX
= 125°C,
θ
JA
≈
30°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the operating temperature range, otherwise specificatons are at T
A
= 25°C. (Note 3)
PARAMETER
Regulated Output Voltage
(Note 4)
CONDITIONS
LT1529-3.3
LT1529-5
LT1529 (Note 5)
Line Regulation
LT1529-3.3
LT1529-5
LT1529 (Note 5)
Load Regulation
LT1529-3.3
LT1529-5
LT1529 (Note 5)
Dropout Voltage
(Note 6)
V
IN
= 3.8V, I
OUT
= 1mA, T
J
= 25°C
4.3V < V
IN
< 15V, 1mA < I
OUT
< 3A
V
IN
= 5.5V, I
OUT
= 1mA, T
J
= 25°C
6V < V
IN
< 15V, 1mA < I
OUT
< 3A
V
IN
= 4.3V, I
OUT
= 1mA, T
J
= 25°C
4.8V < V
IN
< 15V, 1mA < I
OUT
< 3A
∆V
IN
= 3.8V to 15V, I
OUT
= 1mA
∆V
IN
= 5.5V to 15V, I
OUT
= 1mA
∆V
IN
= 4.3V to 15V, I
OUT
= 1mA
∆I
LOAD
= 1mA to 3A, V
IN
= 4.3V, T
J
= 25°C
∆I
LOAD
= 1mA to 3A, V
IN
= 4.3V
∆I
LOAD
= 1mA to 3A, V
IN
= 6V, T
J
= 25°C
∆I
LOAD
= 1mA to 3A, V
IN
= 6V
∆I
LOAD
= 1mA to 3A, V
IN
= 4.8V, T
J
= 25°C
∆I
LOAD
= 1mA to 3A, V
IN
= 4.8V
q
q
q
q
q
q
q
q
q
q
I
LOAD
= 10mA, T
J
= 25°C
I
LOAD
= 10mA
I
LOAD
= 100mA, T
J
= 25°C
I
LOAD
= 100mA
2
U
U
W
W W
U
W
(Note 1)
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.
FRONT VIEW
5
4
3
2
1
T PACKAGE
5-LEAD PLASTIC TO-220
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
T
JMAX
= 125°C,
θ
JA
≈
50°C/ W
V
IN
SHDN
GND
SENSE/ADJ*
OUTPUT
ORDER PART
NUMBER
LT1529CT
LT1529CT-3.3
LT1529CT-5
LT1529IT
LT1529IT-3.3
LT1529IT-5
MIN
3.250
3.200
4.925
4.850
3.695
3.640
TYP
3.300
3.300
5.000
5.000
3.750
3.750
1.5
1.5
1.5
5
12
5
12
5
12
110
200
MAX
3.350
3.400
5.075
5.150
3.805
3.860
10
10
10
20
30
20
30
20
30
180
250
300
400
UNITS
V
V
V
V
V
V
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
q
LT1529
LT1529-3.3/LT1529-5
ELECTRICAL CHARACTERISTICS
PARAMETER
Dropout Voltage
(Note 6)
The
q
denotes specifications which apply over the operating temperature range, otherwise specificatons are at T
A
= 25°C. (Note 3)
CONDITIONS
I
LOAD
= 700mA, T
J
= 25°C
I
LOAD
= 700mA
I
LOAD
= 1.5A, T
J
= 25°C
I
LOAD
= 1.5A
I
LOAD
= 3A, T
J
= 25°C
I
LOAD
= 3A
I
LOAD
= 0mA, T
J
= 25°C
I
LOAD
= 0mA, T
J
= 125°C (Note 8)
I
LOAD
= 100mA, T
J
= 25°C
I
LOAD
= 100mA, T
J
= 125°C (Note 8)
I
LOAD
= 700mA
I
LOAD
= 1.5A
I
LOAD
= 3A
T
J
= 25°C
V
OUT
= Off to On
V
OUT
= On to Off
V
SHDN
= 0V
V
IN
= V
OUT
(Nominal) + 1V, V
SHDN
= 0V
V
IN
– V
OUT
= 1V (Avg), V
RIPPLE
= 0.5V
P-P
,
f
RIPPLE
= 120Hz, I
LOAD
= 1.5A
V
IN
– V
OUT
= 7V, T
J
= 25°C
V
IN
= V
OUT
(Nominal) + 1.5V,
∆V
OUT
= – 0.1V
V
IN
= – 15V, V
OUT
= 0V
LT1529-3.3
V
OUT
= 3.3V, V
IN
= 0V
LT1529-5
V
OUT
= 5V, V
IN
= 0V
LT1529 (Note 6)
V
OUT
= 3.8V, V
IN
= 0V
MIN
q
TYP
320
430
q
600
q
GND Pin Current
(Note 7)
q
q
q
q
q
q
q
ADJ Pin Bias Current (Notes 5, 9)
Shutdown Threshold
SHDN Pin Current (Note 10)
Quiescent Current in Shutdown
(Note 11)
Ripple Rejection
Current Limit
Input Reverse Leakage Current
Reverse Output Current (Note 12)
0.25
50
400
0.6
1.0
5.5
20
80
150
1.20
0.75
4.5
15
62
5
4.7
MAX
430
550
550
700
750
950
100
1.0
12
40
160
300
2.8
10
30
UNITS
mV
mV
mV
mV
mV
mV
µA
µA
mA
mA
mA
mA
mA
nA
V
V
µA
µA
dB
A
A
mA
µA
µA
µA
50
q
q
3.2
1.0
16
16
16
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 (5µA) and the GND pin current (10µA).
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.
3
LT1529
LT1529-3.3/LT1529-5
TYPICAL PERFOR A CE CHARACTERISTICS
Guaranteed Dropout Voltage
1.0
0.9
DROPOUT VOLTAGE (V)
DROPOUT VOLTAGE (V)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
= TEST POINT
0.5
1.5
2.0
1.0
OUTPUT CURRENT (A)
2.5
3.0
0.1
F
0
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
0.8
0.7
0.6
0.5
B
0.4
0.3
0.2
C
D
E
A: I
LOAD
= 3A
E: I
LOAD
= 100mA
B: I
LOAD
= 1.5A
F: I
LOAD
= 10mA
C: I
LOAD
= 700mA
D: I
LOAD
= 300mA
A
QUIESCENT CURRENT (µA)
LT1529-3.3
Quiescent Current
250
225
QUIESCENT CURRENT (µA)
200
175
150
125
100
75
50
25
0
0
1
2
V
SHDN
= 0V
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
V
SHDN
= OPEN (HIGH)
I
LOAD
= 0
R
L
=
∞
QUIESCENT CURRENT (µA)
250
225
200
175
150
125
100
75
50
25
0
QUIESCENT CURRENT (µA)
LT1529-3.3
Output Voltage
3.400
3.375
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
3.350
3.325
3.300
3.275
3.250
3.225
3.200
– 50 – 25
0
75
50
25
TEMPERATURE (°C)
100
125
I
LOAD
= 1mA
5.100
5.075
5.025
5.000
4.975
4.950
4.925
4.900
–50 –25
0
75
50
25
TEMPERATURE (˚C)
100
125
ADJ PIN VOLTAGE (V)
4
U W
Dropout Voltage
250
Quiescent Current
V
IN
= 6V
R
L
=
∞
200
150
100
V
SHDN
= OPEN
50
V
SHDN
= 0V
0
– 50 – 25
50
25
0
75
TEMPERATURE (°C)
100
125
LT1529 • G01
LT1529 • G02
LT1529 • G03
LT1529-5
Quiescent Current
250
I
LOAD
= 0
R
L
=
∞
225
200
175
150
125
100
75
50
25
8
9
10
0
LT1529
Quiescent Current
I
LOAD
= 0
R
L
=
∞
V
OUT
= V
ADJ
V
SHDN
= OPEN (HIGH)
V
SHDN
= OPEN (HIGH)
V
SHDN
= 0V
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
V
SHDN
= 0V
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
LT1529 • G04
LT1529 • G05
LT1529 • G06
LT1529-5
Output Voltage
3.850
I
LOAD
= 1mA
3.825
3.800
3.775
3.750
3.725
3.700
3.675
5.050
LT1529
ADJ Pin Voltage
I
LOAD
= 1mA
3.650
– 50 – 25
0
75
50
25
TEMPERATURE (°C)
100
125
LT1529 • G07
LT1529 • G08
LT1529 • G09
LT1529
LT1529-3.3/LT1529-5
TYPICAL PERFOR A CE CHARACTERISTICS
LT1529-3.3
GND Pin Current
5.0
4.5
4.0
GND PIN CURRENT (mA)
T
J
= 25°C
V
OUT
= V
SENSE
*FOR V
OUT
= 3.3V
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
1
2
GND PIN CURRENT (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
R
LOAD
= 500Ω
I
LOAD
= 10mA*
GND PIN CURRENT (mA)
R
LOAD
= 6.6Ω
I
LOAD
= 500mA*
R
LOAD
= 330Ω
I
LOAD
= 10mA*
R
LOAD
= 11Ω
I
LOAD
= 300mA*
R
LOAD
= 33Ω
I
LOAD
= 100mA*
3 4 5 6 7
INPUT VOLTAGE (V)
LT1529-3.3
GND Pin Current
100
90
80
T
J
= 25°C
*FOR V
OUT
= 3.3V
V
OUT
= V
SENSE
R
LOAD
= 1.1Ω
I
LOAD
= 3A*
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
70
60
50
40
30
20
10
0
0
R
LOAD
= 4.7Ω
I
LOAD
= 700mA*
R
LOAD
= 2.2Ω
I
LOAD
= 1.5A*
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
GND Pin Current
100
90
GND PIN CURRENT (mA)
80
70
60
50
40
30
20
10
0
0
0.5
1.5
2.0
1.0
OUTPUT CURRENT (A)
2.5
3.0
T
J
= 125°C
T
J
= – 50°C
2.0
SHDN THRESHOLD (V)
SHDN THRESHOLD (V)
V
IN
= 3.75V (LT1529)
V
IN
= 3.3V (LT1529-3.3)
V
IN
= 5V (LT1529-5)
DEVICE IS OPERATING
IN DROPOUT
T
J
= 25°C
U W
8
9
10
LT1529 • G10
LT1529-5
GND Pin Current
5.0
T
J
= 25°C
4.5 V
OUT
= V
SENSE
*FOR V
OUT
= 5V
4.0
5.0
LT1529
GND Pin Current
T
J
= 25°C
4.5 V
OUT
= V
ADJ
*FOR V
OUT
=
4.0
3.75V
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
R
LOAD
= 38Ω
I
LOAD
= 100mA*
R
LOAD
= 10Ω
I
LOAD
= 500mA*
R
LOAD
= 7.5Ω
I
LOAD
= 500mA*
R
LOAD
= 375Ω
I
LOAD
= 10mA*
R
LOAD
= 12.5Ω
I
LOAD
= 300mA*
R
LOAD
= 16.6Ω
I
LOAD
= 300mA*
R
LOAD
= 50Ω
I
LOAD
= 100mA*
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
LT1529 • G11
LT1529 • G12
LT1529-5
GND Pin Current
100
90
80
70
60
50
40
30
20
10
8
9
LT1529
GND Pin Current
100
R
LOAD
= 1.7Ω
I
LOAD
= 3A*
T
J
= 25°C
90 V
OUT
= V
ADJ
*FOR V
OUT
= 3.75V
80
70
60
50
40
30
20
10
0
R
LOAD
= 5.3Ω
I
LOAD
= 700mA*
R
LOAD
= 2.5Ω
I
LOAD
= 1.5A*
R
LOAD
= 1.25Ω
I
LOAD
= 3A*
T
J
= 25°C
V
OUT
= V
SENSE
*FOR V
OUT
= 5V
R
LOAD
= 7.1Ω
I
LOAD
= 700mA*
R
LOAD
= 3.3Ω
I
LOAD
= 1.5A*
0
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
LT1529 • G13
LT1529 • G14
LT1529 • G15
SHDN Pin Threshold
(On-to-Off)
2.0
I
LOAD
= 1mA
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
50
25
0
75
TEMPERATURE (°C)
100
125
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
– 50 –25
SHDN Pin Threshold
(Off-to-On)
I
LOAD
= 3A
I
LOAD
= 1mA
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LT1529 • G16
LT1529 • G17
LT1529 • G18
5
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