LT1529CT-5#06PBF [Linear]
LT1529 - 3A Low Dropout Regulators with Micropower Quiescent Current and Shutdown; Package: TO-220; Pins: 5; Temperature Range: 0°C to 70°C;型号: | LT1529CT-5#06PBF |
厂家: | Linear |
描述: | LT1529 - 3A Low Dropout Regulators with Micropower Quiescent Current and Shutdown; Package: TO-220; Pins: 5; Temperature Range: 0°C to 70°C |
文件: | 总12页 (文件大小:146K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1529
LT1529-3.3/LT1529-5
3A Low Dropout Regulators
with Micropower
Quiescent Current
and Shutdown
U
FEATURES
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.
■
Dropout Voltage: 0.6V at IOUT = 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 IQ = 16µA
■
Stable with 22µF Output Capacitor
■
Reverse Battery Protection
Other features of the LT1529 /LT1529-3.3/LT1529-5 in-
clude the ability to operate with small output capacitors.
They are stable with 22µF on the output while most older
devices require up to 100µF for stability. Small ceramic
capacitors can be used, enhancing manufacturabiltiy.
Alsotheinputmaybeconnectedtovoltageslowerthanthe
output voltage, including negative voltages, without re-
verse 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.
■
No Reverse Current
Thermal Limiting
■
U
APPLICATIO S
■
High Efficiency Regulator
■
Regulator for Battery-Powered Systems
■
Post Regulator for Switching Supplies
5V to 3.3V Logic Regulator
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
U
TYPICAL APPLICATIO
Dropout Voltage
0.6
5V Supply with Shutdown
0.5
0.4
0.3
0.2
0.1
0
5
4
1
2
5V
3A
V
OUTPUT
LT1529-5
IN
+
V
> 5.5V
IN
22µF
SHDN SENSE
GND
3
V
(PIN 4) OUTPUT
SHDN
<0.25
>2.8
NC
OFF
ON
ON
LT1529 • TA01
0
1.0
1.5
2.0
2.5
3.0
0.5
OUTPUT CURRENT (A)
LT1529 • TA02
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1
LT1529
LT1529-3.3/LT1529-5
W W W
U
ABSOLUTE AXI U RATI GS (Note 1)
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
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.
W U
/O
PACKAGE RDER I FOR ATIO
FRONT VIEW
FRONT VIEW
ORDER PART
ORDER PART
NUMBER
5
4
3
2
1
V
NUMBER
IN
5
4
3
2
1
V
IN
SHDN
GND
SENSE/ADJ*
OUTPUT
SHDN
TAB IS
GND
TAB IS
GND
GND
SENSE/ADJ*
OUTPUT
LT1529CQ
LT1529CT
LT1529CQ-3.3
LT1529CQ-5
LT1529IQ
LT1529CT-3.3
LT1529CT-5
LT1529IT
Q PACKAGE
5-LEAD PLASTIC DD PAK
T PACKAGE
5-LEAD PLASTIC TO-220
LT1529IQ-3.3
LT1529IQ-5
LT1529IT-3.3
LT1529IT-5
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
*PIN 2 = SENSE FOR LT1529-3.3/LT1529-5
= ADJ FOR LT1529
TJMAX = 125°C, θJA ≈ 30°C/W
TJMAX = 125°C, θJA ≈ 50°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the operating temperature range, otherwise specificatons are at TA = 25°C. (Note 3)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Regulated Output Voltage
(Note 4)
LT1529-3.3
V
= 3.8V, I
= 1mA, T = 25°C
3.250
3.200
3.300
3.300
3.350
3.400
V
V
IN
OUT
J
4.3V < V < 15V, 1mA < I
< 3A
OUT
●
●
IN
LT1529-5
V
= 5.5V, I
= 1mA, T = 25°C
4.925
4.850
5.000
5.000
5.075
5.150
V
V
IN
OUT
J
6V < V < 15V, 1mA < I
< 3A
OUT
IN
LT1529 (Note 5)
V
= 4.3V, I
= 1mA, T = 25°C
3.695
3.640
3.750
3.750
3.805
3.860
V
V
IN
OUT
J
4.8V < V < 15V, 1mA < I
< 3A
OUT
●
●
●
●
IN
Line Regulation
Load Regulation
LT1529-3.3
LT1529-5
∆V = 3.8V to 15V, I
= 1mA
= 1mA
= 1mA
1.5
1.5
1.5
10
10
10
mV
mV
mV
IN
OUT
OUT
OUT
∆V = 5.5V to 15V, I
IN
LT1529 (Note 5)
LT1529-3.3
∆V = 4.3V to 15V, I
IN
∆I
∆I
= 1mA to 3A, V = 4.3V, T = 25°C
= 1mA to 3A, V = 4.3V
5
12
20
30
mV
mV
LOAD
LOAD
IN
IN
J
●
●
●
●
●
LT1529-5
∆I
∆I
= 1mA to 3A, V = 6V, T = 25°C
= 1mA to 3A, V = 6V
5
12
20
30
mV
mV
LOAD
LOAD
IN
J
IN
LT1529 (Note 5)
∆I
∆I
= 1mA to 3A, V = 4.8V, T = 25°C
= 1mA to 3A, V = 4.8V
5
12
20
30
mV
mV
LOAD
LOAD
IN
IN
J
Dropout Voltage
(Note 6)
I
I
= 10mA, T = 25°C
110
200
180
250
mV
mV
LOAD
LOAD
J
= 10mA
I
I
= 100mA, T = 25°C
= 100mA
300
400
mV
mV
LOAD
LOAD
J
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2
LT1529
LT1529-3.3/LT1529-5
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the operating temperature range, otherwise specificatons are at TA = 25°C. (Note 3)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Dropout Voltage
(Note 6)
I
I
I
I
I
I
= 700mA, T = 25°C
= 700mA
320
430
550
550
700
750
950
mV
mV
mV
mV
mV
mV
LOAD
LOAD
J
●
●
●
= 1.5A, T = 25°C
430
600
LOAD
LOAD
J
= 1.5A
= 3A, T = 25°C
LOAD
LOAD
J
= 3A
GND Pin Current
(Note 7)
I
I
= 0mA, T = 25°C
50
400
100
µA
µA
LOAD
LOAD
J
= 0mA, T = 125°C (Note 8)
J
I
I
= 100mA, T = 25°C
0.6
1.0
1.0
mA
mA
LOAD
LOAD
J
= 100mA, T = 125°C (Note 8)
J
I
I
I
= 700mA
= 1.5A
= 3A
●
●
●
5.5
20
80
150
1.20
0.75
12
40
160
300
2.8
mA
mA
mA
nA
V
V
LOAD
LOAD
LOAD
ADJ Pin Bias Current (Notes 5, 9)
Shutdown Threshold
T = 25°C
V
V
J
= Off to On
= On to Off
●
●
OUT
OUT
0.25
SHDN Pin Current (Note 10)
Quiescent Current in Shutdown
(Note 11)
V
V
= 0V
●
●
4.5
15
10
30
µA
µA
SHDN
= V
(Nominal) + 1V, V
= 0V
IN
OUT
SHDN
Ripple Rejection
V
– V
= 1V (Avg), V
= 0.5V
,
50
62
dB
IN
OUT
RIPPLE
P-P
f
= 120Hz, I
= 1.5A
RIPPLE
LOAD
Current Limit
V
V
V
– V
= V
= –15V, V
= 7V, T = 25°C
(Nominal) + 1.5V, ∆V
5
4.7
A
A
mA
µA
µA
µA
IN
IN
OUT
OUT
J
= –0.1V
●
●
3.2
OUT
Input Reverse Leakage Current
Reverse Output Current (Note 12)
= 0V
1.0
IN
OUT
LT1529-3.3
LT1529-5
LT1529 (Note 6)
V
V
V
= 3.3V, V = 0V
16
16
16
OUT
OUT
OUT
IN
= 5V, V = 0V
IN
= 3.8V, V = 0V
IN
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 7: GND pin current is tested with V = V
(nominal) and a current
OUT
IN
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 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 8: GND pin current will rise at T > 75°C. This is due to internal
J
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 3: The device is tested under pulse load conditions such that T = T .
J
A
Note 4: Operating conditions are limited by maximum junction
Note 9: ADJ pin bias current flows into the ADJ pin.
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 10: SHDN pin current at V
= 0V flows out of the SHDN pin.
SHDN
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 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.
IN
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 – V
).
IN
DROPOUT
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3
LT1529
LT1529-3.3/LT1529-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Dropout Voltage
Guaranteed Dropout Voltage
Quiescent Current
250
200
150
100
50
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
= 6V
A: I
LOAD
B: I
LOAD
C: I
LOAD
D: I
LOAD
= 3A
E: I
F: I
= 100mA
= 10mA
IN
L
LOAD
LOAD
R
=
∞
= 1.5A
= 700mA
= 300mA
0.8
0.7
0.6
A
B
0.5
0.4
C
D
E
V
= OPEN
SHDN
0.3
0.2
0.1
0
V
= 0V
SHDN
F
= TEST POINT
0
–50
0
25
50
75 100 125
–25
0
0.5
1.5
2.0
2.5
3.0
–25
0
50
75 100 125
1.0
–50
25
TEMPERATURE (°C)
OUTPUT CURRENT (A)
TEMPERATURE (°C)
LT1529 • G03
LT1529 • G01
LT1529 • G02
LT1529-3.3
Quiescent Current
LT1529-5
Quiescent Current
LT1529
Quiescent Current
250
225
200
175
150
125
100
75
250
225
200
175
150
125
100
75
250
225
200
175
150
125
100
75
I
= 0
I
= 0
I = 0
LOAD
LOAD
L
LOAD
L
R
=
∞
R
=
∞
R = ∞
L
V
= V
ADJ
OUT
V
= OPEN (HIGH)
V
= OPEN (HIGH)
V
= OPEN (HIGH)
SHDN
SHDN
SHDN
50
50
50
V
= 0V
5
V
= 0V
5
V
= 0V
SHDN
SHDN
4
SHDN
25
25
25
0
0
0
0
1
2
3
6
7
8
9
10
0
1
2
3
4
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LT1529 • G04
LT1529 • G05
LT1529 • G06
LT1529-3.3
Output Voltage
LT1529-5
Output Voltage
LT1529
ADJ Pin Voltage
3.400
5.100
3.850
I
= 1mA
I
= 1mA
I
= 1mA
LOAD
LOAD
LOAD
3.375
3.350
5.075
5.050
3.825
3.800
3.325
3.300
3.275
3.250
3.225
5.025
5.000
4.975
4.950
4.925
3.775
3.750
3.725
3.700
3.675
3.200
4.900
3.650
–25
0
50
75 100 125
–25
0
50
75 100 125
–25
0
50
75 100 125
–50
25
–50
25
–50
25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1529 • G07
LT1529 • G08
LT1529 • G09
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LT1529
LT1529-3.3/LT1529-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LT1529-5
GND Pin Current
LT1529
GND Pin Current
LT1529-3.3
GND Pin Current
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5.0
T
= 25°C
T
= 25°C
T
= 25°C
J
J
J
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
V
= V
V
= V
V
= V
ADJ
OUT
SENSE
OUT
SENSE
OUT
*FOR V
= 5V
*FOR V
= 3.3V
*FOR V
3.75V
=
OUT
OUT
OUT
R
I
= 10Ω
R
LOAD
= 7.5Ω
LOAD
R
I
= 6.6Ω
LOAD
LOAD
LOAD
LOAD
= 500mA*
I
= 500mA*
= 500mA*
R
I
= 500Ω
R
I
= 375Ω
= 10mA*
LOAD
LOAD
LOAD
LOAD
= 10mA*
R
= 330Ω
= 10mA*
LOAD
LOAD
I
R
= 12.5Ω
= 300mA*
LOAD
LOAD
I
R
= 16.6Ω
= 300mA*
R
I
= 11Ω
= 300mA*
LOAD
LOAD
LOAD
I
LOAD
R
I
= 33Ω
= 100mA*
R
I
= 38Ω
LOAD
LOAD
R
= 50Ω
LOAD
= 100mA*
LOAD
LOAD
I
= 100mA*
LOAD
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
4
5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LT1529 • G10
LT1529 • G11
LT1529 • G12
LT1529-3.3
GND Pin Current
LT1529
GND Pin Current
LT1529-5
GND Pin Current
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
T
= 25°C
T
= 25°C
J
T
= 25°C
*FOR V
= 3.3V
R
J
J
OUT
V
= V
V
= V
ADJ
V
= V
OUT
SENSE
OUT
OUT
SENSE
R
I
= 1.7Ω
LOAD
LOAD
R
= 1.25W
= 3A*
*FOR V
= 5V
*FOR V
= 3.75V
OUT
LOAD
LOAD
OUT
= 3A*
= 1.1Ω
LOAD
I
I
= 3A*
LOAD
R
= 7.1Ω
LOAD
= 700mA*
I
LOAD
R = 4.7Ω
LOAD
= 700mA*
LOAD
R
= 5.3Ω
= 700mA*
LOAD
LOAD
I
I
R
I
= 2.5Ω
= 1.5A*
R
= 3.3Ω
= 1.5A*
R
LOAD
= 2.2Ω
= 1.5A*
LOAD
LOAD
LOAD
LOAD
LOAD
I
I
1
2
8
9
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
3
4
5
6
7
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LT1529 • G13
LT1529 • G14
LT1529 • G15
SHDN Pin Threshold
(On-to-Off)
SHDN Pin Threshold
(Off-to-On)
GND Pin Current
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
100
90
I
= 1mA
V
V
V
= 3.75V (LT1529)
= 3.3V (LT1529-3.3)
= 5V (LT1529-5)
LOAD
IN
IN
IN
I
= 3A
LOAD
80
70
60
DEVICE IS OPERATING
IN DROPOUT
T
= 25°C
J
I
= 1mA
LOAD
50
40
T
= 125°C
J
T
= –50°C
J
30
20
10
0
50
75 100 125
–50 –25
0
25
50
75 100 125
– 50
0
25
TEMPERATURE (°C)
–25
0
0.5
1.5
2.0
2.5
3.0
1.0
TEMPERATURE (°C)
OUTPUT CURRENT (A)
LT1529 • G17
LT1529 • G18
LT1529 • G16
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5
LT1529
LT1529-3.3/LT1529-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS
SHDN Pin Current
SHDN Pin Input Current
ADJ Pin Bias Current
10
9
8
7
6
5
4
3
2
1
0
500
450
400
350
300
250
200
150
100
50
25
20
V
= 0V
V
= V
= 3.75V
OUT
SHDN
ADJ
15
10
5
0
0
– 50
0 25
TEMPERATURE (°C)
50
75 100 125
–50 –25
0
25
50
75 100 125
–25
0
1
2
3
4
5
6
7
8
9
TEMPERATURE (°C)
SHDN PIN VOLTAGE (V)
LT1529 • G19
LT1529 • G21
LT1529 • G20
Reverse Output Current
Current Limit
Current Limit
150
125
100
75
6
5
4
3
6
5
4
3
2
1
0
V
V
= 7V
V
= 0V
IN
OUT
OUT
= 0V
50
25
0
2
1
0
50
TEMPERATURE (°C)
100 125
0
1
2
3
4
5
6
7
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–50 –25
0
25
75
INPUT VOLTAGE (V)
LT1529 • G22
LT1529 • G23
LT1529 • G24
Reverse Output Current
Ripple Rejection
Ripple Rejection
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
62
60
I = 1.5A
OUT
T
= 25°C, V = 0V
(V – V )AVG = 1V
J
V
IN
IN
OUT
= 0.5V
V
= V
(NOMINAL) + 1
OUT
= V
IN
V
I
OUT
SENSE
RIPPLE
LOAD
f = 120Hz
P-P
+ 50mV
RIPPLE
RMS
(LT1529-3.3/LT1529-5)
V
CURRENT FLOWS
INTO DEVICE
= 1.5A
= V
(LT1529)
OUT
ADJ
58
56
54
52
50
C
= 47µF
OUT
LT1529
C
= 22µF
OUT
LT1529-3.3
LT1529-5
48
10
100
1k
FREQUENCY (Hz)
10k
100k
0
1
2
3
4
5
6
7
8
9
10
–50
25
50
75
100 125
–25
0
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
LT1529 • G27
LT1529 • G25
LT1529 • G26
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6
LT1529
LT1529-3.3/LT1529-5
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TYPICAL PERFOR A CE CHARACTERISTICS
Load Regulation
LT1529-5 Transient Response
LT1529-5 Transient Response
5
0
V
C
C
= 6V
V
C
C
= 6V
IN
IN
IN
IN
LT1529-5
0.2
0.1
0.2
0.1
= 10µF
= 3.3µF
= 47µF
= 22µF
OUT
OUT
0
0
LT1529-3.3
LT1529
–5
–10
–0.1
–0.2
–0.1
–0.2
–15
–20
–25
3
2
1
3
2
1
V
= V
(NOMINAL) + 1V
IN
OUT
∆I
= 100mA to 3A
= V
OUT
LOAD
V
ADJ
50
100 125
200 300
600 700
800 9001000
–50 –25
0
25
75
0
100
400 500
0
20 40 60
120 140 160 180 200
80 100
TEMPERATURE (°C)
TIME (µs)
TIME (µs)
LT1529 • G28
LT1529 • G29
LT1529 • G30
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PI FU CTIO S
R
R
P
5
4
1
2
OUTPUT (Pin 1): OUTPUT Pin. The OUTPUT pin supplies
power to the load. A minimum output capacitor of 22µF is
required to prevent oscillations. Larger values will be
required to optimize transient response for large load
current deltas. See the Applications Information section
for further information on output capacitance and reverse
output characteristics.
V
OUTPUT
LT1529-5
IN
SHDN SENSE
+
LOAD
+
V
GND
3
IN
P
LT1529 • F01
Figure 1. Kelvin Sense Connection
SENSE (Pin 2): SENSE Pin. For fixed voltage versions of
the LT1529 (LT1529-3.3, LT1529-5) the SENSE pin is the
input to the error amplifier. Optimum regulation will be
obtained at the point where the SENSE pin is connected to
the output pin. For most applications the SENSE pin is
connected directly to the OUTPUT pin at the regulator. In
critical applications small voltage drops caused by the
resistance (RP) of PC traces between the regulator and the
load, which would normally degrade regulation, may be
eliminated by connecting the SENSE pin to the OUTPUT
pin at the load as shown in Figure 1 (Kelvin Sense Connec-
tion). Note that the voltage drop across the external PC
traces will add to the dropout voltage of the regulator. The
SENSE pin bias current is 15µA at the nominal regulated
output voltage. This pin is internally clamped to –0.6V
(one VBE).
pin is internally clamped to 6V and –0.6V (one VBE). This
pin has a bias current of 150nA which flows into the pin.
See Bias Current curve in the Typical Performance Char-
acteristics.TheADJpinreferencevoltageisequalto3.75V
referenced to ground.
SHDN (Pin 4): Shutdown Pin. This pin is used to put the
device into shutdown. In shutdown the output of the
device is turned off. This pin is active low. The device will
be shut down if the SHDN pin is actively pulled low. The
SHDNpincurrentwiththepinpulledtogroundwillbe6µA.
The SHDN pin is internally clamped to 7V and –0.6V (one
VBE). This allows the SHDN pin to be driven directly by 5V
logicorbyopen-collectorlogicwithapull-upresistor. The
pull-up resistor is only required to supply the leakage
current of the open-collector gate, normally several mi-
croamperes. Pull-up current must be limited to a maxi-
ADJ (Pin 2): Adjust Pin. For the LT1529 (adjustable
version) the ADJ pin is the input to the error amplifier. This
mum of 5mA. A curve of SHDN pin input current as a
152935fb
7
LT1529
LT1529-3.3/LT1529-5
U
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PI FU CTIO S
include a bypass capacitor in battery-powered circuits. A
bypass capacitor in the range of 1µF to 10µF is sufficient.
The LT1529 is designed to withstand reverse voltages on
the VIN pin with respect to ground and OUTPUT pin. In the
case of a reversed input, which can happen if a battery is
plugged in backwards, the LT1529 will act as if there is a
diode in series with its input. There will be no reverse
current flow into the LT1529 and no reverse voltage will
appear at the load. The device will protect both itself and
the load.
function of voltage appears in the Typical Performance
Characteristics. If the SHDN pin is not used it can be left
open circuit. The device will be active, output on, if the
SHDN pin is not connected.
VIN (Pin 5): Input Pin. Power is supplied to the device
through the VIN pin. The VIN pin should be bypassed to
ground if the device is more than six inches away from the
main input filter capacitor. In general, the output imped-
ance of a battery rises with frequency so it is advisable to
O U
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PPLICATI
A
S I FOR ATIO
5
4
1
2
The LT1529 is a 3A low dropout regulator with mi-
cropower quiescent current and shutdown capable of
supplying 3A of output current at a dropout voltage of
0.6V. The device operates with very low quiescent current
(50µA). In shutdown the quiescent current drops to only
16µA. In addition to the low quiescent current the LT1529
incorporates several protection features which make it
ideal for use in battery-powered systems. The device is
protectedagainstreverseinputvoltages.Inbatterybackup
applications where the output can be held up by a backup
batterywhentheinputispulledtoground,theLT1529acts
like it has a diode in series with its output and prevents
reverse current flow.
V
V
OUTPUT
LT1529
OUT
IN
+
V
R2
R1
IN
SHDN SENSE
GND
3
LT1529 • F02
R2
R1
V
= 3.75V 1 +
+ (I
× R2)
ADJ
OUT
ADJ
(
)
V
I
= 3.75V
= 150nA AT 25°C
ADJ
OUTPUT RANGE = 3.3V TO 14V
Figure 2. Adjustable Operation
Bias Current vs Temperature appear in the Typical Perfor-
mance Characteristics. The reference voltage at the ADJ
pin has a positive temperature coefficient of approxi-
mately15ppm/°C.TheADJpinbiascurrenthasanegative
temperature coefficient. These effects will tend to cancel
each other.
Adjustable Operation
The adjustable version of the LT1529 has an output
voltage range of 3.75V to 14V. The output voltage is set
by the ratio of two external resistors as shown in Figure 2.
The device servos the output voltage to maintain the
voltage at the ADJ pin at 3.75V. The current in R1 is then
equal to 3.75V/R1. The current in R2 is equal to the sum
of the current in R1 and the ADJ pin bias current. The ADJ
pinbiascurrent, 150nAat25°C, flowsthroughR2intothe
ADJ pin. The output voltage can be calculated according
to the formula in Figure 2. The value of R1 should be less
than 400k to minimize errors in the output voltage caused
by the ADJ pin bias current. Note that in shutdown the
output is turned off and the divider current will be zero.
Curves of ADJ Pin Voltage vs Temperature and ADJ Pin
The adjustable device is specified with the ADJ pin tied to
the OUTPUT pin. This sets the output voltage to 3.75V.
Specificationsforoutputvoltagegreaterthan3.75Vwillbe
proportional to the ratio of the desired output voltage to
3.75V (VOUT/3.75V). For example: load regulation for an
output current change of 1mA to 3A is –0.5mV typical at
VOUT = 3.75V. At VOUT = 12V, load regulation would be:
12V
3.75V
⎛
⎜
⎝
⎞
⎟
⎠
–0.5mV = –1.6mV
) (
(
)
152935fb
8
LT1529
LT1529-3.3/LT1529-5
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PPLICATI
Thermal Considerations
S I FOR ATIO
A
tance. The thermal resistance for each application will be
affectedbythermalinteractionswithothercomponentsas
well as board size and shape. Some experimentation will
be necessary to determine the actual value.
The power handling capability of the device will be limited
by the maximum rated junction temperature (125°C). The
power dissipated by the device will be made up of two
components:
Table 1. Q Package, 5-Lead DD
COPPER AREA
TOPSIDE* BACKSIDE
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
1. Output current multiplied by the input/output voltage
differential: IOUT • (VIN – VOUT), and
BOARD AREA
2500 sq. mm 2500 sq. mm 2500 sq. mm
1000 sq. mm 2500 sq. mm 2500 sq. mm
125 sq. mm 2500 sq. mm 2500 sq. mm
* Device is mounted on topside.
23°C/W
25°C/W
33°C/W
2. Ground pin current multiplied by the input voltage:
IGND • VIN .
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Character-
istics.Powerdissipationwillbeequaltothesumofthetwo
components listed above.
T Package, 5-Lead TO-220
Thermal Resistance (Junction-to-Case) = 2.5°C/W
Calculating Junction Temperature
The LT1529 series regulators have internal thermal limit-
ing designed to protect the device during overload condi-
tions. For continuous normal load conditions the maxi-
mum junction temperature rating of 125°C must not be
exceeded. It is important to give careful consideration to
allsourcesofthermalresistancefromjunctiontoambient.
Additional heat sources mounted nearby must also be
considered.
Example: Given an output voltage of 3.3V, an input voltage
range of 4.5V to 5.5V, an output current range of 0mA to
500mA, and a maximum ambient temperature of 50°C,
what will the maximum junction temperature be?
The power dissipated by the device will be equal to:
IOUT(MAX) • (VIN(MAX) – VOUT) + (IGND • VIN(MAX)
)
where, IOUT(MAX) = 500mA
For surface mount devices heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Experiments have shown that the
heat spreading copper layer does not need to be electri-
cally connected to the tab of the device. The PC material
can be very effective at transmitting heat between the pad
area, attached to the tab of the device, and a ground or
power plane layer either inside or on the opposite side of
theboard.AlthoughtheactualthermalresistanceofthePC
material is high, the length/area ratio of the thermal
resistor between layers is small. Copper board stiffeners
and plated through-holes can also be used to spread the
heat generated by power devices.
VIN(MAX) = 5.5V
IGND at (IOUT = 500mA, VIN = 5.5V) = 3.6mA
so,
P = 500mA • (5.5V – 3.3V) + (3.6mA • 5.5V)
= 1.12W
If we use a DD package, then the thermal resistance will be
in the range of 23°C/W to 33°C/W depending on copper
area. So the junction temperature rise above ambient will
be approximately equal to:
1.12W • 28°C/W = 31.4°C
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
The following tables list thermal resistances for each
package. For the TO-220 package, thermal resistance is
given for junction-to-case only since this package is
usually mounted to a heat sink. Measured values of
thermal resistance for several different copper areas are
listed for the DD package. All measurements were taken in
stillairon3/32"FR-4boardwith1-ozcopper.Thisdatacan
be used as a rough guideline in estimating thermal resis-
TJMAX = 50°C + 31.4°C = 81.4°C
Output Capacitance and Transient Performance
The LT1529 is designed to be stable with a wide range of
output capacitors. The minimum recommended value is
22µF with an ESR of 0.2Ω or less. The LT1529 is a
152935fb
9
LT1529
LT1529-3.3/LT1529-5
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PPLICATI
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S I FOR ATIO
micropower device and output transient response will be
a function of output capacitance. See the Transient Re-
sponsecurvesintheTypicalPerformanceCharacteristics.
Larger values of output capacitance will decrease the peak
deviations and provide improved output transient re-
sponse for larger load current deltas. Bypass capacitors,
used to decouple individual components powered by the
LT1529, will increase the effective value of the output
capacitor.
OUTPUT pin of an adjustable device, or the SENSE pin of
a fixed voltage device, is pulled below ground, with the
input open or grounded, current must be limited to less
than 5mA.
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
voltage may be held up while the input is either pulled to
ground, pulled to some intermediate voltage, or is left
open circuit. Current flow back into the output will vary
depending on the conditions. Many battery-powered cir-
cuits incorporate some form of power management. The
following information will help optimize battery life. Table
2 summarizes the following information.
Protection Features
TheLT1529incorporatesseveralprotectionfeatureswhich
make it ideal for use in battery-powered circuits. In addi-
tion to the normal protection features associated with
monolithic regulators, such as current limiting and ther-
mal limiting, the device is protected against reverse input
voltages, and reverse voltages from output to input.
The reverse output current will follow the curve in Figure
3 when the input is pulled to ground. This current flows
through the device to ground. The state of the SHDN pin
will have no effect on output current when the VIN pin is
pulled to ground.
Current limit protection and thermal overload protection
areintendedtoprotectthedeviceagainstcurrentoverload
conditions at the output of the device. For normal opera-
tion, the junction temperature should not exceed 125°C.
100
T = 25°C, V = 0V
J
V
IN
90
80
70
60
50
40
30
20
10
0
= V
OUT
SENSE
(LT1529-3.3/LT1529-5)
V
= V
(LT1529)
OUT
ADJ
The input of the device will withstand reverse voltages of
15V.Currentflowintothedevicewillbelimitedtolessthan
1mA (typically less than 100µA) and no negative voltage
will appear at the output. The device will protect both itself
and the load. This provides protection against batteries
that can be plugged in backwards.
CURRENT FLOWS
INTO DEVICE
LT1529
LT1529-3.3
LT1529-5
For fixed voltage versions of the device, the SENSE pin is
internally clamped to one diode drop below ground. For
the adjustable version of the device, the OUTPUT pin is
internally clamped at one diode drop below ground. If the
0
1
2
3
4
5
6
7
8
9
10
OUTPUT VOLTAGE (V)
LT1529 • F03
Figure 3. Reverse Output Current
Table 2. Fault Conditions
V
PIN
SHDN PIN
Open (High)
Grounded
OUTPUT/SENSE PINS
IN
<V
<V
(Nominal)
(Nominal)
Forced to V
Forced to V
(Nominal)
(Nominal)
Reverse Output Current ≈ 15µA (See Figure 3), Input Current ≈ 1µA (See Figure 4)
Reverse Output Current ≈ 15µA (See Figure 3), Input Current ≈ 1µA (See Figure 4)
Reverse Output Current ≈ 15µA Peak (See Figure 3)
Reverse Output Current ≈ 15µA (See Figure 3)
Output Current = 0
OUT
OUT
OUT
OUT
Open
Open
Open (High)
Grounded
> 1V
> 1V
≤0V
≤0V
≤0V
≤0V
≤0.8V
≤0.8V
>1.5V
Open (High)
Grounded
Output Current = 0
Open (High)
Grounded
Output Current = Short-Circuit Current
–15V < V < 15V
Output Current = 0
IN
152935fb
10
LT1529
LT1529-3.3/LT1529-5
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PPLICATI
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S I FOR ATIO
Insomeapplicationsitmaybenecessarytoleavetheinput
to the LT1529 unconnected when the output is held high.
This can happen when the LT1529 is powered from a
rectified AC source. If the AC source is removed, then the
input of the LT1529 is effectively left floating. The reverse
output current also follows the curve in Figure 3 if the VIN
pin is left open. The state of the SHDN pin will have no
effect on the reverse output current when the VIN pin is
floating.
willtypicallydroptolessthan2µA(seeFigure4). Thestate
of the SHDN pin will have no effect on the reverse output
current when the output is pulled above the input.
5
V
V
= 3.3V (LT1529-3.3)
= 5V (LT1529-5)
OUT
OUT
4
3
2
1
0
LT1529-3.3
LT1529-5
When the input of the LT1529 is forced to a voltage below
its nominal output voltage and its output is held high, the
outputcurrentwillfollowthecurveshowninFigure3.This
can happen if the input of the LT1529 is connected to a
discharged (low voltage) battery and the output is held up
by either a backup battery or by a second regulator circuit.
When the VIN pin is forced below the OUTPUT pin or the
OUTPUT pin is pulled above the VIN pin, the input current
0
1
2
3
4
5
INPUT VOLTAGE (V)
LT1529 • F04
Figure 4. Input Current
U
PACKAGE DESCRIPTIO
Q Package
5-Lead Plastic DD Pak
(LTC DWG # 05-08-1461)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
.060
(1.524)
.165 – .180
(4.191 – 4.572)
.256
(6.502)
.045 – .055
(1.143 – 1.397)
15° TYP
+.008
–.004
+0.203
–0.102
.004
.060
(1.524)
.059
(1.499)
TYP
.183
(4.648)
.330 – .370
(8.382 – 9.398)
0.102
(
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.067
(1.702)
BSC
.050 ± .012
(1.270 ± 0.305)
.300
(7.620)
.013 – .023
(0.330 – 0.584)
+.012
.143
–.020
.028 – .038
+0.305
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
3.632
Q(DD5) 0502
(0.711 – 0.965)
(
)
–0.508
TYP
.420
.276
.420
.080
.350
.325
.205
.320
.067
.565
.565
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.090
.042
RECOMMENDED SOLDER PAD LAYOUT
.090
.042
.067
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
152935fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of circuits as described herein will not infringe on existing patent rights.
11
LT1529
LT1529-3.3/LT1529-5
U
PACKAGE DESCRIPTIO
T Package
5-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1421)
.165 – .180
(4.191 – 4.572)
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.045 – .055
(1.143 – 1.397)
.230 – .270
(5.842 – 6.858)
.570 – .620
(14.478 – 15.748)
.620
(15.75)
TYP
.460 – .500
(11.684 – 12.700)
.330 – .370
(8.382 – 9.398)
.700 – .728
(17.78 – 18.491)
.095 – .115
(2.413 – 2.921)
SEATING PLANE
.152 – .202
(3.861 – 5.131)
.155 – .195*
(3.937 – 4.953)
.260 – .320
(6.60 – 8.13)
.013 – .023
(0.330 – 0.584)
.067
BSC
.135 – .165
(3.429 – 4.191)
.028 – .038
(0.711 – 0.965)
(1.70)
* MEASURED AT THE SEATING PLANE
T5 (TO-220) 0801
RELATED PARTS
PART NUMBER
LT1120A
LTC®1174
LT1303
DESCRIPTION
COMMENTS
125mA Low Dropout Regulator with 20µA I
Includes 2.5V Reference and Comparator
Over 90% Efficiency, Includes Comparator
Includes Comparator, Good for EL Displays
Uses Extremely Small External Components
Q
High Efficiency 425mA Step-Down DC/DC Converter
Micropower Step-Up DC/DC Converter
LT1376
500kHz 1.25A Step-Down DC/DC Converter
LT1521
300µA Low Dropout Regulator with 15µA I
Lowest I Low Dropout Regulator
Q
Q
152935fb
LT/LT 0305 REV B • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
©LINEAR TECHNOLOGY CORPORATION 1995
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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