LT3080EMS8E-TR [Linear]
Adjustable1.1A Single Resistor Low Dropout Regulator; Adjustable1.1A单电阻低压差稳压器型号: | LT3080EMS8E-TR |
厂家: | Linear |
描述: | Adjustable1.1A Single Resistor Low Dropout Regulator |
文件: | 总26页 (文件大小:283K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT3080
Adjustable1.1A Single
Resistor Low Dropout
Regulator
FEATURES
DESCRIPTION
TheLT®3080isa1.1Alowdropoutlinearregulatorthatcan
be paralleled to increase output current or spread heat in
surface mounted boards. Architected as a precision cur-
rent source and voltage follower allows this new regulator
to be used in many applications requiring high current,
adjustability to zero, and no heat sink. Also the device
brings out the collector of the pass transistor to allow low
dropout operation —down to 350 millivolts— when used
with multiple supplies.
n
Outputs May be Paralleled for Higher Current and
Heat Spreading
n
Output Current: 1.1A
n
Single Resistor Programs Output Voltage
1% Initial Accuracy of SET Pin Current
Output Adjustable to 0V
Low Output Noise: 40μV
n
n
n
(10Hz to 100kHz)
RMS
n
n
Wide Input Voltage Range: 1.2V to 36V
Low Dropout Voltage: 350mV (Except SOT-223
Package)
A key feature of the LT3080 is the capability to supply a
wide output voltage range. By using a reference current
throughasingleresistor,theoutputvoltageisprogrammed
to any level between zero and 36V. The LT3080 is stable
with 2.2μF of capacitance on the output, and the IC uses
small ceramic capacitors that do not require additional
ESR as is common with other regulators.
n
n
n
n
n
<1mV Load Regulation
<0.001%/V Line Regulation
Minimum Load Current: 0.5mA
Stable with 2.2μF Minimum Ceramic Output Capacitor
Current Limit with Foldback and Overtemperature
Protected
n
Available in 8-Lead MSOP, 3mm × 3mm DFN,
5-Lead DD-Pak, TO-220 and 3-Lead SOT-223
Internal protection circuitry includes current limiting and
thermal limiting. The LT3080 regulator is offered in the
8-lead MSOP (with an exposed pad for better thermal
characteristics), a 3mm × 3mm DFN, 5-lead DD-Pak,
TO-220 and a simple-to-use 3-lead SOT-223 version.
APPLICATIONS
n
High Current All Surface Mount Supply
n
High Efficiency Linear Regulator
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and VLDO
and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
n
Post Regulator for Switching Supplies
n
Low Parts Count Variable Voltage Supply
n
Low Output Voltage Power Supplies
Set Pin Current Distribution
TYPICAL APPLICATION
Variable Output Voltage 1.1A Supply
N = 13792
IN
LT3080
V
IN
1.2V TO 36V
V
CONTROL
+
–
1μF
OUT
V
OUT
SET
2.2μF
R
V
SET
= R
• 10μA
SET
OUT
10.00
SET PIN CURRENT DISTRIBUTION (μA)
9.80
9.90
10.10
10.20
3080 TA01a
3080 G02
3080fb
1
LT3080
ABSOLUTE MAXIMUM RATINGS (Note 1)(All Voltages Relative to VOUT
)
V
Pin Voltage..................................... 40V, –0.3V
Operating Junction Temperature Range
CONTROL
IN Pin Voltage ................................................ 40V, –0.3V
SET Pin Current (Note 7) ..................................... 10mA
SET Pin Voltage (Relative to OUT) ......................... 0.3V
Output Short-Circuit Duration .......................... Indefinite
(Notes 2, 10).......................................... –40°C to 125°C
Storage Temperature Range:.................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MS8E, Q, T and ST Packages Only.................... 300°C
PIN CONFIGURATION
TOP VIEW
FRONT VIEW
TOP VIEW
9
5
4
3
2
1
IN
V
OUT
OUT
OUT
SET
1
2
3
4
8
7
6
5
IN
IN
NC
V
OUT
OUT
OUT
SET
1
2
3
4
8 IN
7 IN
6 NC
5 V
CONTROL
9
TAB IS
OUT
OUT
SET
NC
CONTROL
CONTROL
MS8E PACKAGE
8-LEAD PLASTIC MSOP
DD PACKAGE
Q PACKAGE
T
= 125°C, θ = 60°C/W, θ = 10°C/W
JA JC
JMAX
8-LEAD (3mm × 3mm) PLASTIC DFN
5-LEAD PLASTIC DD-PAK
EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB
T
= 125°C, θ = 64°C/W, θ = 3°C/W
T
= 125°C, θ = 30°C/W, θ = 3°C/W
JMAX
JA
JC
JMAX
JA
JC
EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB
FRONT VIEW
FRONT VIEW
5
3
2
1
IN*
IN
TAB IS
OUT
4
V
CONTROL
OUT
SET
TAB IS
OUT
3
OUT
SET
NC
2
1
ST PACKAGE
3-LEAD PLASTIC SOT-223
*IN IS V AND IN TIED TOGETHER
T PACKAGE
5-LEAD PLASTIC TO-220
CONTROL
= 125°C, θ = 55°C/W, θ = 15°C/W
T
= 125°C, θ = 40°C/W, θ = 3°C/W
JA JC
JMAX
T
JMAX
JA
JC
ORDER INFORMATION
LEAD FREE FINISH
LT3080EDD#PBF
LT3080EMS8E#PBF
LT3080EQ#PBF
LT3080ET#PBF
LT3080EST#PBF
LEAD BASED FINISH
LT3080EDD
TAPE AND REEL
LT3080EDD#TRPBF
LT3080EMS8E#TRPBF
LT3080EQ#TRPBF
LT3080ET#TRPBF
LT3080EST#TRPBF
TAPE AND REEL
LT3080EDD#TR
PART MARKING
LCBN
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
8-Lead (3mm × 3mm) Plastic DFN
8-Lead Plastic MSOP
LTCBM
LT3080EQ
LT3080ET
3080
5-Lead Plastic DD-Pak
5-Lead Plastic TO-220
3-Lead Plastic SOT-223
PACKAGE DESCRIPTION
8-Lead (3mm × 3mm) Plastic DFN
8-Lead Plastic MSOP
PART MARKING
LCBN
LT3080EMS8E
LT3080EQ
LT3080EMS8E#TR
LT3080EQ#TR
LTCBM
LT3080EQ
LT3080ET
3080
5-Lead Plastic DD-Pak
LT3080ET
LT3080ET#TR
5-Lead Plastic TO-220
LT3080EST
LT3080EST#TR
3-Lead Plastic SOT-223
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
3080fb
2
LT3080
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 11)
PARAMETER
CONDITIONS
MIN
TYP MAX UNITS
SET Pin Current
I
V
V
= 1V, V
≥ 1V, V
= 2.0V, I
= 1mA, T = 25°C
LOAD
9.90
9.80
10
10
10.10
10.20
μA
μA
SET
IN
IN
CONTROL
CONTROL
LOAD
J
l
l
l
≥ 2.0V, 1mA ≤ I
≤ 1.1A (Note 9)
Output Offset Voltage (V
– V
)
V
OS
DFN and MSOP Package
–2
–3.5
2
3.5
mV
mV
OUT
SET
V
= 1V, V
= 2V, I = 1mA
OUT
IN
CONTROL
SOT-223, DD-Pak and T0-220 Package
–5
–6
5
6
mV
mV
Load Regulation
–0.1
0.6
nA
ΔI
ΔI
ΔI
= 1mA to 1.1A
SET
OS
LOAD
LOAD
l
l
1.3
0.5
mV
ΔV
= 1mA to 1.1A (Note 8)
Line Regulation (Note 9)
DFN and MSOP Package
V
V
= 1V to 25V, V
= 2V to 25V, I = 1mA
LOAD
= 2V to 25V, I
0.1
0.003
nA/V
mV/V
ΔI
ΔV
IN
CONTROL
CONTROL
SET
OS
= 1V to 25V, V
= 1mA
IN
LOAD
l
Line Regulation (Note 9)
SOT-223, DD-Pak and T0-220 Package
ΔI
V
V
= 1V to 26V, V
= 1V to 26V, V
= 2V to 26V, I
= 2V to 26V, I
= 1mA
= 1mA
0.1
0.003
0.5
nA/V
mV/V
SET
OS
IN
IN
CONTROL
CONTROL
LOAD
LOAD
ΔV
l
l
l
Minimum Load Current (Notes 3, 9)
V
IN
V
IN
V
IN
= V
= V
= V
= 10V
300
500
1
1
μA
mA
mA
CONTROL
CONTROL
CONTROL
= 25V (DFN and MSOP Package)
= 26V (SOT-223, DD-Pak and T0-220 Package)
V
V
V
Dropout Voltage (Note 4)
Pin Current
I
I
= 100mA
= 1.1A
1.2
V
V
CONTROL
LOAD
LOAD
l
1.35
1.6
l
l
Dropout Voltage (Note 4)
I
I
= 100mA
= 1.1A
100
350
200
500
mV
mV
IN
LOAD
LOAD
l
l
I
I
= 100mA
= 1.1A
4
17
6
30
mA
mA
CONTROL
LOAD
LOAD
l
Current Limit
V
= 5V, V
= 5V, V = 0V, V = –0.1V
OUT
1.1
1.4
40
1
A
IN
CONTROL
SET
Error Amplifier RMS Output Noise (Note 6)
I
= 1.1A, 10Hz ≤ f ≤ 100kHz, C
= 10μF, C = 0.1μF
μV
LOAD
OUT
SET
RMS
RMS
Reference Current RMS Output Noise (Note 6)
Ripple Rejection
10Hz ≤ f ≤ 100kHz
nA
f = 120Hz, V
f = 10kHz
f = 1MHz
= 0.5V , I
= 0.2A, C = 0.1μF, C = 2.2μF
75
55
20
dB
dB
dB
RIPPLE
P-P LOAD
SET
OUT
Thermal Regulation, I
10ms Pulse
0.003
%/W
SET
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.
resistor shot noise and reference current noise; output noise is then equal
to error amplifier noise (see Applications Information section).
Note 7: SET pin is clamped to the output with diodes. These diodes only
carry current under transient overloads.
Note 2: Unless otherwise specified, all voltages are with respect to V
.
OUT
Note 8: Load regulation is Kelvin sensed at the package.
Note 9: Current limit may decrease to zero at input-to-output differential
The LT3080 is tested and specified under pulse load conditions such that
T ≈ T . The LT3080 E-Grade is 100% tested at T = 25°C. Performance at
J
A
A
voltages (V –V ) greater than 25V (DFN and MSOP package) or 26V
IN OUT
–40°C and 125°C is assured by design, characterization and correlation
with statistical process controls.
(SOT-223, DD-Pak and T0-220 Package). Operation at voltages for both IN
and V
is allowed up to a maximum of 36V as long as the difference
CONTROL
Note 3: Minimum load current is equivalent to the quiescent current of
the part. Since all quiescent and drive current is delivered to the output
of the part, the minimum load current is the minimum current required to
maintain regulation.
between input and output voltage is below the specified differential
(V –V ) voltage. Line and load regulation specifications are not
IN OUT
applicable when the device is in current limit.
Note 10: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
when overtemperature protection is active. Continuous operation above
the specified maximum operating junction temperature may impair device
reliability.
Note 4: For the LT3080, dropout is caused by either minimum control
voltage (V
) or minimum input voltage (V ). Both parameters are
CONTROL
IN
specified with respect to the output voltage. The specifications represent the
minimum input-to-output differential voltage required to maintain regulation.
Note 5: The V
pin current is the drive current required for the
CONTROL
output transistor. This current will track output current with roughly a 1:60
ratio. The minimum value is equal to the quiescent current of the device.
Note 6: Output noise is lowered by adding a small capacitor across the
Note 11: The SOT-223 package connects the IN and V
together internally. Therefore, test conditions for this pin follow the
V conditions listed in the Electrical Characteristics Table.
CONTROL
pins
CONTROL
voltage setting resistor. Adding this capacitor bypasses the voltage setting
3080fb
3
LT3080
TYPICAL PERFORMANCE CHARACTERISTICS
Set Pin Current
Set Pin Current Distribution
Offset Voltage (VOUT – VSET
)
10.20
10.15
10.10
10.05
10.00
9.95
2.0
1.5
I
L
= 1mA
N = 13792
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
9.90
9.85
9.80
10.00
SET PIN CURRENT DISTRIBUTION (μA)
50 75
TEMPERATURE (°C)
9.80
9.90
10.10
10.20
50 75
TEMPERATURE (°C)
–50 –25
0
25
100 125 150
–50 –25
0
25
100 125 150
3080 G02
3080 G01
3080 G03
Offset Voltage Distribution
Offset Voltage
Offset Voltage
1.00
0.25
0
I
= 1mA
LOAD
N = 13250
0.75
0.50
0.25
T
= 25°C
J
–0.25
–0.50
T
= 125°C
J
0
–0.75
–1.00
–0.25
–0.50
–0.75
–1.00
–1.25
–1.50
–1.75
6
12
24
0
30
36*
0
18
–2
–1
V
1
2
0.2
0.4
0.8
0
1.0
1.2
0.6
INPUT-TO-OUTPUT VOLTAGE (V)
DISTRIBUTION (mV)
LOAD CURRENT (A)
OS
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
3080 G05
3080 G04
3080 G06
Dropout Voltage
(Minimum IN Voltage)
Load Regulation
Minimum Load Current
0
–0.1
–0.2
–0.3
–0.4
–0.5
–0.6
–0.7
–0.8
20
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
400
350
300
250
ΔI
V
= 1mA TO 1.1A
OUT
LOAD
– V
= 2V
IN
10
T
= 125°C
J
CHANGE IN REFERENCE CURRENT
V
V
– V
– V
= 36V*
= 1.5V
0
IN, CONTROL
IN, CONTROL
OUT
OUT
–10
–20
–30
–40
–50
–60
T
= 25°C
J
CHANGE IN OFFSET VOLTAGE
200
150
(V
– V
)
SET
OUT
100
50
0
50 75
25
TEMPERATURE (°C)
50 75
TEMPERATURE (°C)
0
0.2
0.4
0.8
1.0
1.2
–50 –25
0
100 125 150
–50 –25
0
25
100 125 150
0.6
OUTPUT CURRENT (A)
3080 G07
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
3080 G08
3080 G09
3080fb
4
LT3080
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
Dropout Voltage (Minimum
VCONTROL Pin Voltage)
Dropout Voltage (Minimum
VCONTROL Pin Voltage)
(Minimum IN Voltage)
1.6
1.4
1.2
1.0
400
350
300
250
200
150
100
50
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
T
= –50°C
J
I
= 1.1A
LOAD
I
= 1.1A
LOAD
T
= 125°C
J
I
= 1mA
LOAD
T
= 25°C
J
I
I
= 500mA
LOAD
LOAD
0.8
0.6
0.4
0.2
0
= 100mA
0
0.2
0.4
0.8
0
1.0
1.2
50 75
TEMPERATURE (°C)
0.6
–50 –25
0
25
100 125 150
–50 –25
50 75
TEMPERATURE (°C)
0
25
100 125
150
OUTPUT CURRENT (A)
3080 G11
3080 G10
3080 G12
Current Limit
Current Limit
Load Transient Response
75
50
1.6
1.4
1.2
1.0
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
C
V
= 1.5V
OUT
SET
IN
T
= 25°C
J
= 0.1μF
= V
CONTROL
= 3V
SOT-223, DD-PAK
AND TO-220
25
0
–25
–50
400
300
200
100
0
C
= 10μF CERAMIC
OUT
0.8
0.6
C
= 2.2μF CERAMIC
OUT
MSOP
AND
0.4
0.2
0
DFN
V
V
= 7V
IN
OUT
= 0V
6
12
24
0
30
36*
0
5
10 15 20 25 30 35 40 45 50
50 75
TEMPERATURE (°C)
18
–50 –25
0
25
100 125 150
INPUT-TO-OUTPUT DIFFERENTIAL (V)
TIME (μs)
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
3080 G14
3080 G15
3080 G13
Turn-On Response
Load Transient Response
Line Transient Response
5
4
150
100
50
75
50
25
0
3
2
0
1
–50
–100
1.2
0.9
0.6
0.3
0
–25
–50
6
R
= 100k
= 0
SET
SET
C
V
= 1.5V
= 10mA
= 2.2μF
OUT
0
R
C
= 1Ω
LOAD
I
LOAD
C
= 2.2μF CERAMIC
2.0
1.5
1.0
0.5
0
OUT
OUT
V
V
C
C
= V
= 3V
CONTROL
CERAMIC
= 0.1μF
SET
CERAMIC
IN
5
= 1.5V
C
OUT
OUT
SET
= 10μF CERAMIC
= 0.1μF
4
3
2
0
1
2
3
4
5
6
7
8
9
10
0
5
10 15 20 25 30 35 40 45 50
0
10 20 30 40 50 60 70 80 90 100
TIME (μs)
TIME (μs)
TIME (μs)
3080 G27
3080 G16
3080 G17
3080fb
5
LT3080
TYPICAL PERFORMANCE CHARACTERISTICS
Residual Output Voltage with
Less Than Minimum Load
VCONTROL Pin Current
VCONTROL Pin Current
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
25
20
15
10
30
25
20
15
10
5
SET PIN = 0V
V
V
– V
= 2V
OUT
CONTROL
– V
= 1V
OUT
V
IN
V
IN
OUT
TEST
R
I
= 1.1A
LOAD
DEVICE IN
CURRENT LIMIT
T
= –50°C
J
V
= 10V
IN
V
= 20V
IN
T
J
= 25°C
V
IN
= 5V
T
= 125°C
J
5
0
I
= 1mA
12
LOAD
6
0
0
1k
2k
0
18
24
30
36*
0
0.4
0.6
0.8
1.0
1.2
0.2
INPUT-TO-OUTPUT DIFFERENTIAL (V)
LOAD CURRENT (A)
R
(Ω)
TEST
3080 G20
3080 G18
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
3080 G19
Ripple Rejection, Dual Supply,
IN Pin
Ripple Rejection, Dual Supply,
VCONTROL Pin
Ripple Rejection, Single Supply
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
I
= 100mA
I
= 100mA
LOAD
LOAD
I
= 1.1A
I
= 1.1A
LOAD
LOAD
V
V
= V
+ 1V
OUT (NOMINAL)
IN
CONTROL
= V
+2V
OUT (NOMINAL)
P-P
V
V
C
= V
+ 1V
OUT (NOMINAL)
IN
CONTROL
RIPPLE = 50mV
V
= V
= V
P-P
+ 2V
100k
= V
+2V
OUT (NOMINAL)
IN
CONTROL
OUT (NOMINAL)
C
I
= 2.2µF CERAMIC
= 1.1A
OUT
RIPPLE = 50mV
= 2.2µF CERAMIC
OUT
LOAD
C
= 2.2µF CERAMIC
RIPPLE = 50mV
OUT
P-P
10
100
1k
10k
100k
1M
10
100
1k
10k
1M
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
3080 G23
3080 G21
3080 G22
Noise Spectral Density
Ripple Rejection (120Hz)
80
79
78
77
76
75
74
73
72
71
70
10k
1k
1k
100
100
10
1
10
SINGLE SUPPLY OPERATION
1.0
V
= V
+ 2V
IN
OUT(NOMINAL)
RIPPLE = 500mV , f = 120Hz
P-P
I
= 1.1A
LOAD
C
= 0.1μF, C
= 2.2μF
OUT
SET
0.1
100k
–50
50
100 125
150
10
100
1k
FREQUENCY (Hz)
10k
–25
0
25
75
TEMPERATURE (°C)
3080 G25
3080 G24
3080fb
6
LT3080
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Noise
Error Amplifier Gain and Phase
20
300
250
200
150
100
50
15
10
V
OUT
100μV/DIV
I
= 1.1A
5
0
L
I
= 100mA
L
–5
3080 G26
TIME 1ms/DIV
V
= 1V
OUT
I
L
= 1.1A
–10
–15
–20
–25
–30
0
R
= 100k
= O.1μF
= 10μF
= 1.1A
SET
SET
OUT
C
C
I
–50
I
= 100mA
L
–100
–150
–200
LOAD
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
3080 G28
PIN FUNCTIONS (DD/MS8E/Q/T/ST)
V
(Pin 5/Pin 5/Pin 4/Pin 4/NA): This pin is the
OUT (Pins 1-3/Pins 1-3/Pin 3/Pin 3/Pin 2): This is the
power output of the device. There must be a minimum
load current of 1mA or the output may not regulate.
CONTROL
supply pin for the control circuitry of the device. The cur-
rent flow into this pin is about 1.7% of the output current.
For the device to regulate, this voltage must be more than
1.2Vto1.35Vgreaterthantheoutputvoltage(seedropout
specifications).
SET (Pin 4/Pin 4/Pin 2/Pin 2/Pin 1): This pin is the input
to the error amplifier and the regulation set point for
the device. A fixed current of 10μA flows out of this pin
through a single external resistor, which programs the
output voltage of the device. Output voltage range is zero
to the absolute maximum rated output voltage. Transient
performance can be improved by adding a small capacitor
from the SET pin to ground.
IN (Pins 7, 8/Pins 7, 8/Pin 5/Pin 5/Pin 3): This is the
collector to the power device of the LT3080. The output
load current is supplied through this pin. For the device
to regulate, the voltage at this pin must be more than
0.1V to 0.5V greater than the output voltage (see dropout
specifications).
Exposed Pad (Pin 9/Pin 9/NA/NA/NA): OUT on MS8E and
DFN packages.
NC (Pin 6/Pin 6/Pin 1/Pin 1/NA): No Connection. No con-
nect pins have no connection to internal circuitry and may
TAB: OUT on DD-Pak, TO-220 and SOT-223 packages.
be tied to V , V
, V , GND or floated.
IN CONTROL OUT
3080fb
7
LT3080
BLOCK DIAGRAM
IN
V
CONTROL
10μA
+
–
3080 BD
SET
OUT
APPLICATIONS INFORMATION
The LT3080 regulator is easy to use and has all the pro-
tection features expected in high performance regulators.
Included are short-circuit protection and safe operating
area protection, as well as thermal shutdown.
LT1086 have a change in loop gain with output voltage
as well as bandwidth changes when the adjustment pin
is bypassed to ground. For the LT3080, the loop gain is
unchanged by changing the output voltage or bypassing.
Output regulation is not fixed at a percentage of the output
voltage but is a fixed fraction of millivolts. Use of a true
current source allows all the gain in the buffer amplifier
to provide regulation and none of that gain is needed to
amplify up the reference to a higher output voltage.
TheLT3080isespeciallywellsuitedtoapplicationsneeding
multiple rails. The new architecture adjusts down to zero
with a single resistor handling modern low voltage digital
IC’saswellasallowingeasyparalleloperationandthermal
managementwithoutheatsinks.Adjustingto“zero”output
allows shutting off the powered circuitry and when the
input is pre-regulated—such as a 5V or 3.3V input supply
—external resistors can help spread the heat.
The LT3080 has the collector of the output transistor
connected to a separate pin from the control input. Since
the dropout on the collector (IN pin) is only 350mV, two
supplies can be used to power the LT3080 to reduce dis-
sipation: a higher voltage supply for the control circuitry
and a lower voltage supply for the collector. This increases
efficiency and reduces dissipation. To further spread the
heat, a resistor can be inserted in series with the collector
to move some of the heat out of the IC and spread it on
the PC board.
A precision “0” TC 10μA internal current source is con-
nected to the noninverting input of a power operational
amplifier. The power operational amplifier provides a low
impedancebufferedoutputtothevoltageonthenoninvert-
ing input. A single resistor from the noninverting input to
ground sets the output voltage and if this resistor is set
to zero, zero output results. As can be seen, any output
voltage can be obtained from zero up to the maximum
defined by the input power supply.
TheLT3080canbeoperatedintwomodes. Three-terminal
mode has the control pin connected to the power input pin
which gives a limitation of 1.35V dropout. Alternatively,
the “control” pin can be tied to a higher voltage and the
power IN pin to a lower voltage giving 350mV dropout
on the IN pin and minimizing the power dissipation. This
What is not so obvious from this architecture are the ben-
efitsofusingatrueinternalcurrentsourceasthereference
asopposedtoabootstrappedreferenceinolderregulators.
A true current source allows the regulator to have gain
and frequency response independent of the impedance on
the positive input. Older adjustable regulators, such as the
allowsfora1.1Asupplyregulatingfrom2.5V to1.8V
IN
OUT
or 1.8V to 1.2V
with low dissipation.
IN
OUT
3080fb
8
LT3080
APPLICATIONS INFORMATION
If guardring techniques are used, this bootstraps any
stray capacitance at the SET pin. Since the SET pin is
a high impedance node, unwanted signals may couple
into the SET pin and cause erratic behavior. This will
be most noticeable when operating with minimum
output capacitors at full load current. The easiest way
to remedy this is to bypass the SET pin with a small
amount of capacitance from SET to ground, 10pF to
20pF is sufficient.
IN
LT3080
V
CONTROL
+
–
+
+
V
V
CONTROL
IN
OUT
V
C
OUT
SET
R
OUT
C
SET
SET
3080 F01
Stability and Output Capacitance
Figure 1. Basic Adjustable Regulator
The LT3080 requires an output capacitor for stability. It
is designed to be stable with most low ESR capacitors
(typically ceramic, tantalum or low ESR electrolytic).
A minimum output capacitor of 2.2μF with an ESR of 0.5Ω
or less is recommended to prevent oscillations. Larger
values of output capacitance decrease peak deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT3080, increase
the effective output capacitor value.
Output Voltage
The LT3080 generates a 10μA reference current that flows
out of the SET pin. Connecting a resistor from SET to
ground generates a voltage that becomes the reference
point for the error amplifier (see Figure 1). The reference
voltage is a straight multiplication of the SET pin current
and the value of the resistor. Any voltage can be generated
and there is no minimum output voltage for the regulator.
A minimum load current of 1mA is required to maintain
regulation regardless of output voltage. For true zero
voltage output operation, this 1mA load current must be
returned to a negative supply voltage.
Forimprovementintransientperformance,placeacapaci-
tor across the voltage setting resistor. Capacitors up to
1μF can be used. This bypass capacitor reduces system
noise as well, but start-up time is proportional to the time
With the low level current used to generate the reference
voltage, leakage paths to or from the SET pin can create
errors in the reference and output voltages. High quality
insulation should be used (e.g., Teflon, Kel-F); cleaning
of all insulating surfaces to remove fluxes and other resi-
dues will probably be required. Surface coating may be
necessary to provide a moisture barrier in high humidity
environments.
constant of the voltage setting resistor (R in Figure 1)
SET
and SET pin bypass capacitor.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common
dielectrics used are specified with EIA temperature char-
acteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but they tend to have strong volt-
age and temperature coefficients as shown in Figures 2
and 3. When used with a 5V regulator, a 16V 10μF Y5V
capacitor can exhibit an effective value as low as 1μF to
2μF for the DC bias voltage applied and over the operating
temperature range. The X5R and X7R dielectrics result in
more stable characteristics and are more suitable for use
as the output capacitor. The X7R type has better stability
across temperature, while the X5R is less expensive and is
Board leakage can be minimized by encircling the SET
pin and circuitry with a guard ring operated at a potential
close to itself; the guard ring should be tied to the OUT
pin. Guarding both sides of the circuit board is required.
Bulk leakage reduction depends on the guard ring width.
Ten nanoamperes of leakage into or out of the SET pin and
associated circuitry creates a 0.1% error in the reference
voltage. Leakages of this magnitude, coupled with other
sources of leakage, can cause significant offset voltage
and reference drift, especially over the possible operating
temperature range.
3080fb
9
LT3080
APPLICATIONS INFORMATION
20
ceramic capacitor the stress can be induced by vibrations
in the system or thermal transients.
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
0
X5R
Paralleling Devices
–20
LT3080’smaybeparalleledtoobtainhigheroutputcurrent.
The SET pins are tied together and the IN pins are tied
together. This is the same whether it’s in three terminal
mode or has separate input supplies. The outputs are
connected in common using a small piece of PC trace
as a ballast resistor to equalize the currents. PC trace
resistance in milliohms/inch is shown in Table 1. Only a
tiny area is needed for ballasting.
–40
–60
Y5V
–80
–100
0
8
12 14
2
4
6
10
16
DC BIAS VOLTAGE (V)
3080 F02
Figure 2. Ceramic Capacitor DC Bias Characteristics
Table 1. PC Board Trace Resistance
WEIGHT (oz)
10 mil WIDTH
54.3
20 mil WIDTH
27.1
40
20
1
2
27.1
13.6
Trace resistance is measured in mOhms/in
X5R
0
–20
The worse case offset between the set pin and the output
of only 2 millivolts allows very small ballast resistors
to be used. As shown in Figure 4, the two devices have
a small 10 milliohm ballast resistor, which at full output
current gives better than 80 percent equalized sharing
of the current. The external resistance of 10 milliohms
–40
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
3080 F03
V
IN
LT3080
Figure 3. Ceramic Capacitor Temperature Characteristics
V
CONTROL
+
–
availableinhighervalues.Carestillmustbeexercisedwhen
using X5R and X7R capacitors; the X5R and X7R codes
only specify operating temperature range and maximum
capacitancechangeovertemperature.Capacitancechange
due to DC bias with X5R and X7R capacitors is better than
Y5V and Z5U capacitors, but can still be significant enough
to drop capacitor values below appropriate levels. Capaci-
tor DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verified.
10mΩ
OUT
SET
V
LT3080
IN
V
IN
4.8V TO 28V
V
CONTROL
+
–
1μF
10mΩ
V
3.3V
2A
OUT
OUT
SET
165k
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric microphone works. For a
10μF
3080 F04
Figure 4. Parallel Devices
3080fb
10
LT3080
APPLICATIONS INFORMATION
(5milliohmsforthetwodevicesinparallel)onlyaddsabout
10 millivolts of output regulation drop at an output of 2A.
Even with an output voltage as low as 1V, this only adds
1% to the regulation. Of course, more than two LT3080’s
can be paralleled for even higher output current. They are
spread out on the PC board, spreading the heat. Input
resistors can further spread the heat if the input-to-output
difference is high.
temperature of about 90°C, about 65°C above ambient
as shown in Figure 6. Again, the temperature matching
between the devices is within 2°C, showing excellent
tracking between the devices. The board temperature has
reached approximately 40°C within about 0.75 inches of
each device.
While90°Cisanacceptableoperatingtemperatureforthese
devices, this is in 25°C ambient. For higher ambients, the
temperaturemustbecontrolledtopreventdevicetempera-
ture from exceeding 125°C. A 3-meter-per-second airflow
across the devices will decrease the device temperature
about 20°C providing a margin for higher operating ambi-
ent temperatures.
Thermal Performance
In this example, two LT3080 3mm × 3mm DFN devices
are mounted on a 1oz copper 4-layer PC board. They are
placed approximately 1.5 inches apart and the board is
mounted vertically for convection cooling. Two tests were
set up to measure the cooling performance and current
sharing of these devices.
Both at low power and relatively high power levels de-
vices can be paralleled for higher output current. Current
sharing and thermal sharing is excellent, showing that
acceptable operation can be had while keeping the peak
temperatures below excessive operating temperatures on
a board. This technique allows higher operating current
linear regulation to be used in systems where it could
never be used before.
The first test was done with approximately 0.7V input-
to-output and 1A per device. This gave a 700 milliwatt
dissipation in each device and a 2A output current. The
temperature rise above ambient is approximately 28°C
and both devices were within plus or minus 1°C. Both the
thermal and electrical sharing of these devices is excel-
lent. The thermograph in Figure 5 shows the temperature
distribution between these devices and the PC board
reaches ambient temperature within about a half an inch
from the devices.
Quieting the Noise
The LT3080 offers numerous advantages when it comes
to dealing with noise. There are several sources of noise
in a linear regulator. The most critical noise source for any
LDO is the reference; from there, the noise contribution
The power is then increased with 1.7V across each device.
Thisgives1.7wattsdissipationineachdeviceandadevice
Figure 5. Temperature Rise at 700mW Dissipation
Figure 6. Temperature Rise at 1.7W Dissipation
3080fb
11
LT3080
APPLICATIONS INFORMATION
from the error amplifier must be considered, and the gain
created by using a resistor divider cannot be forgotten.
current limit as the input-to-output voltage increases and
keeps the power dissipation at safe levels for all values
of input-to-output voltage. The LT3080 provides some
output current at all values of input-to-output voltage up
to the device breakdown. See the Current Limit curve in
the Typical Performance Characteristics.
Traditional low noise regulators bring the voltage refer-
ence out to an external pin (usually through a large value
resistor) to allow for bypassing and noise reduction of
reference noise. The LT3080 does not use a traditional
voltage reference like other linear regulators, but instead
uses a reference current. That current operates with typi-
When power is first turned on, the input voltage rises and
the output follows the input, allowing the regulator to start
intoveryheavyloads. Duringstart-up, astheinputvoltage
is rising, the input-to-output voltage differential is small,
allowing the regulator to supply large output currents.
With a high input voltage, a problem can occur wherein
removal of an output short will not allow the output volt-
age to recover. Other regulators, such as the LT1085 and
LT1764A, also exhibit this phenomenon so it is not unique
to the LT3080.
cal noise current levels of 3.2pA/√Hz (1nA
over the
RMS
10Hz to 100kHz bandwidth). The voltage noise of this
is equal to the noise current multiplied by the resistor
value. The resistor generates spot noise equal to √4kTR
–23
(k = Boltzmann’s constant, 1.38 • 10
J/°K, and T is
absolute temperature) which is RMS summed with the
reference current noise. To lower reference noise, the
voltage setting resistor may be bypassed with a capacitor,
though this causes start-up time to increase as a factor
of the RC time constant.
The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low. Com-
mon situations are immediately after the removal of a
short circuit. The load line for such a load may intersect
the output current curve at two points. If this happens,
there are two stable operating points for the regulator.
With this double intersection, the input power supply may
need to be cycled down to zero and brought up again to
make the output recover.
The LT3080 uses a unity-gain follower from the SET pin
to drive the output, and there is no requirement to use
a resistor to set the output voltage. Use a high accuracy
voltage reference placed at the SET pin to remove the er-
rors in output voltage due to reference current tolerance
and resistor tolerance. Active driving of the SET pin is
acceptable; the limitations are the creativity and ingenuity
of the circuit designer.
Oneproblemthatanormallinearregulatorseeswithrefer-
ence voltage noise is that noise is gained up along with the
output when using a resistor divider to operate at levels
higherthanthenormalreferencevoltage.WiththeLT3080,
the unity-gain follower presents no gain whatsoever from
the SET pin to the output, so noise figures do not increase
accordingly. Error amplifier noise is typically 125nV/√Hz
Load Regulation
BecausetheLT3080isafloatingdevice(thereisnoground
pin on the part, all quiescent and drive current is delivered
to the load), it is not possible to provide true remote load
sensing. Load regulation will be limited by the resistance
(40μV
over the 10Hz to 100kHz bandwidth); this is
RMS
IN
LT3080
another factor that is RMS summed in to give a final noise
figure for the regulator.
V
CONTROL
PARASITIC
+
–
Curves in the Typical Performance Characteristics show
noise spectral density and peak-to-peak noise character-
istics for both the reference current and error amplifier
over the 10Hz to 100kHz bandwidth.
RESISTANCE
R
P
R
P
R
P
OUT
LOAD
R
SET
SET
Overload Recovery
3080 F07
LikemanyICpowerregulators,theLT3080hassafeoperat-
ing area (SOA) protection. The SOA protection decreases
Figure 7. Connections for Best Load Regulation
3080fb
12
LT3080
APPLICATIONS INFORMATION
of the connections between the regulator and the load.
The data sheet specification for load regulation is Kelvin
sensed at the pins of the package. Negative side sensing
is a true Kelvin connection, with the bottom of the voltage
setting resistor returned to the negative side of the load
(see Figure 7). Connected as shown, system load regula-
tion will be the sum of the LT3080 load regulation and the
parasitic line resistance multiplied by the output current.
It is important to keep the positive connection between
the regulator and load as short as possible and use large
wire or PC board traces.
Table 2. MSE Package, 8-Lead MSOP
COPPER AREA
THERMAL RESISTANCE
TOPSIDE* BACKSIDE BOARD AREA
(JUNCTION-TO-AMBIENT)
2
2
2
2
2
2
2
2
2
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
55°C/W
57°C/W
60°C/W
65°C/W
2
1000mm
2
225mm
100mm
2
*Device is mounted on topside
Table 3. DD Package, 8-Lead DFN
COPPER AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2
2
2
2
2
2
2
2
2
Thermal Considerations
2500mm
1000mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
60°C/W
62°C/W
65°C/W
68°C/W
2
The LT3080 has internal power and thermal limiting cir-
cuitry designed to protect it under overload conditions.
For continuous normal load conditions, maximum junc-
tion temperature must not be exceeded. It is important
to give consideration to all sources of thermal resistance
from junction to ambient. This includes junction-to-case,
case-to-heat sink interface, heat sink resistance or circuit
board-to-ambient as the application dictates. Additional
heat sources nearby must also be considered.
2
225mm
100mm
2
*Device is mounted on topside
Table 4. ST Package, 3-Lead SOT-223
COPPER AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2
2
2
2
2
2
2
2
2
2500mm
1000mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
48°C/W
48°C/W
56°C/W
62°C/W
2
2
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
anditscoppertraces.Surfacemountheatsinksandplated
through-holes can also be used to spread the heat gener-
ated by power devices.
225mm
100mm
2
*Device is mounted on topside
Table 5. Q Package, 5-Lead DD-Pak
COPPER AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
Junction-to-case thermal resistance is specified from the
IC junction to the bottom of the case directly below the
die. This is the lowest resistance path for heat flow. Proper
mounting is required to ensure the best possible thermal
flow from this area of the package to the heat sinking
material. For the TO-220 package, thermal compound is
strongly recommended for mechanical connections to a
heat sink. A thermally conductive spacer can be used for
electrical isolation as long as the added contribution to
thermal resistance is considered. Note that the Tab or
Exposed Pad (depending on package) is electrically
connected to the output.
TOPSIDE* BACKSIDE BOARD AREA
2
2
2
2
2
2
2
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
25°C/W
30°C/W
35°C/W
2
1000mm
2
125mm
*Device is mounted on topside
T Package, 5-Lead TO-220
Thermal Resistance (Junction-to-Case) = 3°C/W
Calculating Junction Temperature
Example: Given an output voltage of 0.9V, a V
CONTROL
voltage of 3.3V 10%, an IN voltage of 1.5V 5%, output
current range from 1mA to 1A and a maximum ambient
temperature of 50°C, what will the maximum junction
The following tables list thermal resistance for several
different copper areas given a fixed board size. All mea-
surements were taken in still air on two-sided 1/16” FR-4
board with one ounce copper.
2
temperature be for the DFN package on a 2500mm board
with topside copper area of 500mm ?
2
3080fb
13
LT3080
APPLICATIONS INFORMATION
The power in the drive circuit equals:
Junction Temperature will be equal to:
T = T + P • θ (approximated using tables)
P
= (V
– V )(I
OUT CONTROL
)
DRIVE
CONTROL
J
A
TOTAL
JA
where I
is equal to I /60. I
is a function
canbefound
T = 50°C + 721mW • 64°C/W = 96°C
CONTROL
ofoutputcurrent. AcurveofI
OUT
CONTROL
J
vsI
CONTROL
OUT
In this case, the junction temperature is below the maxi-
mum rating, ensuring reliable operation.
in the Typical Performance Characteristics curves.
The power in the output transistor equals:
Reducing Power Dissipation
P
= (V – V )(I
)
OUTPUT
IN
OUT OUT
In some applications it may be necessary to reduce
the power dissipation in the LT3080 package without
sacrificing output current capability. Two techniques are
available. The first technique, illustrated in Figure 8, em-
ploys a resistor in series with the regulator’s input. The
voltagedropacrossRS decreasestheLT3080’sIN-to-OUT
differential voltage and correspondingly decreases the
LT3080’s power dissipation.
The total power equals:
= P + P
OUTPUT
P
TOTAL
DRIVE
The current delivered to the SET pin is negligible and can
be ignored.
V
V
V
= 3.630V (3.3V + 10%)
CONTROL(MAX CONTINUOUS)
= 1.575V (1.5V + 5%)
IN(MAX CONTINUOUS)
As an example, assume: V = V
= 5V, V
= 3.3V
IN
CONTROL
OUT
= 0.9V, I
= 1A, T = 50°C
A
OUT
OUT
and I
= 1A. Use the formulas from the Calculating
OUT(MAX)
Power dissipation under these conditions is equal to:
PDRIVE = (V – V )(I
Junction Temperature section previously discussed.
)
OUT CONTROL
CONTROL
WithoutseriesresistorR ,powerdissipationintheLT3080
S
equals:
IOUT
1A
ICONTROL
=
=
=17mA
60 60
= (3.630V – 0.9V)(17mA) = 46mW
1A
60
PTOTAL = 5V –3.3V •
+ 5V –3.3V •1A
(
)
(
)
P
P
P
DRIVE
= (V – V )(I )
OUT OUT
=1.73W
OUTPUT
OUTPUT
IN
= (1.575V – 0.9V)(1A) = 675mW
If the voltage differential (V ) across the NPN pass
DIFF
transistor is chosen as 0.5V, then R equals:
S
Total Power Dissipation = 721mW
5V –3.3V−0.5V
RS =
=1.2Ω
1A
V
V
IN
IN
Power dissipation in the LT3080 now equals:
V
C1
CONTROL
R
S
LT3080
IN
ʹ
1A
PTOTAL = 5V –3.3V •
+ 0.5V •1A =0.53W
(
)
(
)
60
+
–
TheLT3080’spowerdissipationisnowonly30%compared
to no series resistor. R dissipates 1.2W of power. Choose
OUT
S
V
OUT
appropriate wattage resistors to handle and dissipate the
power properly.
C2
SET
3080 F08
R
SET
Figure 8. Reducing Power Dissipation Using a Series Resistor
3080fb
14
LT3080
APPLICATIONS INFORMATION
The second technique for reducing power dissipation,
shown in Figure 9, uses a resistor in parallel with the
LT3080. This resistor provides a parallel path for current
flow, reducing the current flowing through the LT3080.
This technique works well if input voltage is reasonably
constant and output load current changes are small. This
technique also increases the maximum available output
current at the expense of minimum load requirements.
The maximum total power dissipation is (5.5V – 3.2V) •
1A = 2.3W. However the LT3080 supplies only:
5.5V –3.2V
1A –
=0.36A
3.6Ω
Therefore, the LT3080’s power dissipation is only:
= (5.5V – 3.2V) • 0.36A = 0.83W
P
DIS
R dissipates 1.47W of power. As with the first technique,
As an example, assume: V = V
= 5V, V
OUT(MAX)
=
P
IN
CONTROL
= 3.2V, I
IN(MAX)
= 1A and
choose appropriate wattage resistors to handle and dis-
sipate the power properly. With this configuration, the
LT3080 supplies only 0.36A. Therefore, load current can
increase by 0.64A to 1.64A while keeping the LT3080 in
its normal operating range.
5.5V, V
= 3.3V, V
OUT
OUT(MIN)
I
= 0.7A. Also, assuming that R carries no more
OUT(MIN)
P
than 90% of I
= 630mA.
OUT(MIN)
Calculating R yields:
P
5.5V –3.2V
RP =
=3.65Ω
0.63A
(5% Standard value = 3.6Ω)
V
IN
V
C1
CONTROL
LT3080
IN
R
P
+
–
OUT
V
OUT
C2
SET
3080 F09
R
SET
Figure 9. Reducing Power Dissipation Using a Parallel Resistor
3080fb
15
LT3080
TYPICAL APPLICATIONS
Higher Output Current
Adding Shutdown
MJ4502
V
IN
IN
LT3080
V
6V
IN
50Ω
IN
LT3080
V
CONTROL
+
–
V
CONTROL
+
OUT
100μF
+
–
V
OUT
SET
R1
1μF
V
3.3V
5A
OUT
OUT
Q1
VN2222LL
Q2*
VN2222LL
ON OFF
1N4148
+
SET
4.7μF
100μF
332k
SHUTDOWN
3080 TA04
*Q2 INSURES ZERO OUTPUT
IN THE ABSENCE OF ANY
OUTPUT LOAD.
3080 TA02
Current Source
Low Dropout Voltage LED Driver
V
IN
IN
LT3080
V
V
IN
C1
CONTROL
100mA
D1
10V
LT3080
IN
V
CONTROL
1μF
+
–
+
–
1Ω
OUT
I
OUT
0A TO 1A
OUT
SET
4.7μF
SET
R1
24.9k
100k
R2
2.49Ω
3080 TA03
3080 TA05
Using a Lower Value SET Resistor
V
IN
LT3080
IN
12V
V
CONTROL
+
–
C1
1μF
OUT
V
OUT
0.5V TO 10V
SET
R1
49.9k
1%
V
= 0.5V + 1mA • R
OUT
SET
R2
499Ω
1%
C
1mA
OUT
4.7μF
R
SET
10k
3080 TA06
3080fb
16
LT3080
TYPICAL APPLICATIONS
Coincident Tracking
IN
LT3080
V
CONTROL
IN
LT3080
+
–
V
CONTROL
OUT
V
OUT3
5V
IN
LT3080
V
IN
+
–
SET
4.7μF
7V TO 28V
169k
3080 TA08
V
CONTROL
OUT
V
OUT2
3.3V
+
–
SET
R2
C3
4.7μF
C1
1.5μF
80.6k
V
2.5V
1A
OUT1
OUT
SET
R1
C2
4.7μF
249k
Adding Soft-Start
IN
LT3080
V
IN
4.8V to 28V
V
CONTROL
+
–
D1
C1
1μF
1N4148
V
3.3V
1A
OUT
OUT
SET
R1
C
OUT
C2
0.01μF
4.7μF
332k
3080 TA07
Lab Supply
IN
LT3080
IN
LT3080
V
IN
12V TO 18V
V
V
CONTROL
CONTROL
+
–
+
–
+
15μF
1Ω
OUT
OUT
V
OUT
0V TO 10V
SET
SET
R4
+
+
15μF
4.7μF
100μF
100k
0A TO 1A
1MEG
3080 TA09
3080fb
17
LT3080
TYPICAL APPLICATIONS
High Voltage Regulator
6.1V
10k
V
IN
50V
1N4148
IN
LT3080
BUZ11
V
CONTROL
+
+
–
10μF
V
OUT
OUT
1A
V
OUT
V
OUT
= 20V
= 10μA • R
SET
+
4.7μF
SET
R
SET
15μF
2MEG
3080 TA10
Ramp Generator
Reference Buffer
IN
LT3080
IN
LT3080
V
IN
V
IN
5V
V
CONTROL
V
CONTROL
+
–
+
–
1μF
OUT
OUT
V
V
*
OUT
OUT
INPUT
OUTPUT
C2
SET
SET
4.7μF
3080 TA11
LT1019
4.7μF
C1
1μF
VN2222LL
1N4148
VN2222LL
1μF
GND
*MIN LOAD 0.5mA
3080 TA12
Ground Clamp
Boosting Fixed Output Regulators
LT3080
IN
LT3080
V
V
V
IN
EXT
V
+
CONTROL
20Ω
–
+
–
OUT
20mΩ
SET
OUT
1μF
OUT
20mΩ
42Ω*
3.3V
2.6A
OUT
LT1963-3.3
5V
1N4148
4.7μF
10μF
47μF
5k
3080 TA20
33k
3080 TA13
*4mV DROP ENSURES LT3080 IS
OFF WITH NO LOAD
MULTIPLE LT3080’S CAN BE USED
3080fb
18
LT3080
TYPICAL APPLICATIONS
Low Voltage, High Current Adjustable High Efficiency Regulator*
0.47μH
10k
PV
SV
SW
IN
+
2×
†
I
2.7V TO 5.5V
IN
LT3080
100μF
IN
TH
+
12.1k
294k
2×
100μF
470pF
LTC3414
R
2.2MEG 100k
1000pF
T
2N3906
V
CONTROL
PGOOD
RUN/SS
+
–
V
FB
OUT
20mΩ
78.7k
124k
SYNC/MODE
SGND PGND
SET
IN
LT3080
V
CONTROL
+
–
*DIFFERENTIAL VOLTAGE ON LT3080
IS 0.6V SET BY THE V OF THE 2N3906 PNP.
BE
OUT
20mΩ
†
0V TO 4V
4A
†
MAXIMUM OUTPUT VOLTAGE IS 1.5V
BELOW INPUT VOLTAGE
SET
IN
LT3080
V
CONTROL
+
–
OUT
20mΩ
SET
IN
LT3080
V
CONTROL
+
–
OUT
20mΩ
3080 TA18
SET
+
100μF
100k
3080fb
19
LT3080
TYPICAL APPLICATIONS
Adjustable High Efficiency Regulator*
CMDSH-4E
†
4.5V TO 25V
V
BOOST
SW
IN
10μF
1μF
LT3493
0.1μF
10μH
100k
IN
LT3080
SHDN
TP0610L
68μF
0.1μF
V
MBRM140
CONTROL
200k
+
–
FB
GND
†
OUT
0V TO 10V
1A
4.7μF
10k
3080 TA19
SET
1MEG
*DIFFERENTIAL VOLTAGE ON LT3080
10k
≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD.
†
MAXIMUM OUTPUT VOLTAGE IS 2V
BELOW INPUT VOLTAGE
2 Terminal Current Source
C
*
COMP
IN
LT3080
V
CONTROL
+
–
R1
SET
100k
3080 TA21
1V
R1
I
=
*C
OUT
COMP
R1 ≤ 10Ω 10μF
R1 ≥ 10Ω 2.2μF
3080fb
20
LT3080
PACKAGE DESCRIPTION
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
0.70 p0.05
3.5 p0.05
2.10 p0.05 (2 SIDES)
1.65 p0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.50
BSC
2.38 p0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
R = 0.125
0.40 p 0.10
TYP
5
8
3.00 p0.10
(4 SIDES)
1.65 p 0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
(DD8) DFN 0509 REV C
4
1
0.25 p 0.05
0.75 p0.05
0.200 REF
0.50 BSC
2.38 p0.10
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
3080fb
21
LT3080
PACKAGE DESCRIPTION
MS8E Package
8-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1662 Rev F)
BOTTOM VIEW OF
EXPOSED PAD OPTION
1.88
(.074)
1.68
1
0.29
REF
0.889 p 0.127
(.035 p .005)
1.88 p 0.102
(.074 p .004)
(.066)
0.05 REF
DETAIL “B”
5.23
(.206)
MIN
3.20 – 3.45
1.68 p 0.102
(.066 p .004)
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
(.126 – .136)
DETAIL “B”
8
NO MEASUREMENT PURPOSE
3.00 p 0.102
0.52
(.0205)
REF
(.118 p .004)
(NOTE 3)
0.65
(.0256)
BSC
0.42 p 0.038
(.0165 p .0015)
TYP
8
7 6
5
RECOMMENDED SOLDER PAD LAYOUT
3.00 p 0.102
(.118 p .004)
(NOTE 4)
4.90 p 0.152
(.193 p .006)
DETAIL “A”
0o – 6o TYP
0.254
(.010)
GAUGE PLANE
1
2
3
4
0.53 p 0.152
(.021 p .006)
1.10
(.043)
MAX
0.86
(.034)
REF
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.1016 p 0.0508
(.004 p .002)
0.65
(.0256)
BSC
MSOP (MS8E) 0210 REV F
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
6. EXPOSED PAD DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD
SHALL NOT EXCEED 0.254mm (.010") PER SIDE.
3080fb
22
LT3080
PACKAGE DESCRIPTION
Q Package
5-Lead Plastic DD-Pak
(Reference 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)
15o TYP
+.008
.004
–.004
.060
(1.524)
.059
(1.499)
TYP
.183
(4.648)
.330 – .370
(8.382 – 9.398)
+0.203
–0.102
0.102
ꢀ
ꢁ
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.067
(1.702)
BSC
.050 p .012
(1.270 p 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
.080
.420
.350
.325
.205
.565
.565
.320
.090
.042
.090
.042
.067
.067
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
3080fb
23
LT3080
PACKAGE DESCRIPTION
T Package
5-Lead Plastic TO-220 (Standard)
(Reference 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
ST Package
3-Lead Plastic SOT-223
(Reference LTC DWG # 05-08-1630)
.248 – .264
(6.30 – 6.71)
.129 MAX
.114 – .124
(2.90 – 3.15)
.059 MAX
.264 – .287
(6.70 – 7.30)
.248 BSC
.130 – .146
(3.30 – 3.71)
.039 MAX
.059 MAX
.090
BSC
.181 MAX
RECOMMENDED SOLDER PAD LAYOUT
.033 – .041
(0.84 – 1.04)
.0905
(2.30)
BSC
10o – 16o
.010 – .014
10o
MAX
.071
(1.80)
MAX
(0.25 – 0.36)
10o – 16o
.0008 – .0040
(0.0203 – 0.1016)
.024 – .033
(0.60 – 0.84)
.012
(0.31)
MIN
.181
(4.60)
BSC
ST3 (SOT-233) 0502
3080fb
24
LT3080
REVISION HISTORY (Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
6/10
Made minor updates to Features and Description sections
Revised Line Regulation Conditions and Note 2
Made minor text edits in Applications Information section
Added 200k resistor to drawing 3080 TA19 in Typical Applications section
Updated Package Description drawings
1
3
9
20
21, 22
3080fb
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
25
LT3080
TYPICAL APPLICATION
Paralleling Regulators
IN
LT3080
V
CONTROL
+
–
20mΩ
OUT
SET
IN
LT3080
V
IN
4.8V TO 28V
V
CONTROL
+
–
20mΩ
V
3.3V
2A
OUT
OUT
1μF
SET
165k
10μF
3080 TA14
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LDOs
LT1086
1.5A Low Dropout Regulator
Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output
LT1117
800mA Low Dropout Regulator
800mA Low Dropout Regulator
1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages
OK for Sinking and Sourcing, S0-8 and SOT-223 Packages
LT1118
LT1963A
1.5A Low Noise, Fast Transient Response LDO
340mV Dropout Voltage, Low Noise: 40μV
, V = 2.5V to 20V,
RMS IN
TO-220, DD-Pak, SOT-223 and SO-8 Packages
LT1965
1.1A Low Noise LDO
290mV Dropout Voltage, Low Noise 40μV , V = 1.8V to 20V,
RMS IN
V
= 1.2V to 19.5V, Stable with Ceramic Caps TO-220, DD-Pak,
OUT
MSOP and 3mm × 3mm DFN packages.
LTC®3026
1.5A Low Input Voltage VLDOTM Regulator
V : 1.14V to 3.5V (Boost Enabled), 1.14V to 5.5V (with External 5V),
IN
V
= 0.1V, I = 950μA, Stable with 10μF Ceramic Capacitors, 10-Lead
Q
DO
MSOP and DFN Packages
Switching Regulators
LT1976
High Voltage, 1.5A Step-Down Switching Regulator
f = 200kHz, I = 100μA, TSSOP-16E Package
Q
LTC3414
4A (I ), 4MHz Synchronous Step-Down DC/DC
95% Efficiency, V : 2.25V to 5.5V, V
= 0.8V, TSSOP Package
OUT
IN
OUT(MIN)
Converter
LTC3406/LTC3406B 600mA (I ), 1.5MHz Synchronous Step-Down DC/DC
95% Efficiency, V : 2.5V to 5.5V, V
= 0.6V, I = 20μA,
Q
OUT
IN
OUT(MIN)
Converter
I
< 1μA, ThinSOTTM Package
SD
LTC3411
1.25A (I ), 4MHz Synchronous Step-Down DC/DC
95% Efficiency, V : 2.5V to 5.5V, V
SD
= 0.8V, I = 60μA,
Q
OUT
IN
OUT(MIN)
Converter
I
< 1μA, 10-Lead MS or DFN Packages
3080fb
LT 0610 REV B • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
26
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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