LINER LBRT 20ma, 3v to 80v low dropout micropower linear regulator Datasheet

LT3014
20mA, 3V to 80V
Low Dropout Micropower
Linear Regulator
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FEATURES
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DESCRIPTIO
The LT®3014 is a high voltage, micropower low dropout
linear regulator. The device is capable of supplying 20mA
of output current with a dropout voltage of 350mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (7µA operating and 1µA in
shutdown) makes the LT3014 an ideal choice. Quiescent
current is also well controlled in dropout.
Wide Input Voltage Range: 3V to 80V
Low Quiescent Current: 7µA
Low Dropout Voltage: 350mV
Output Current: 20mA
LT3014HV Survives 100V Transients (2ms)
No Protection Diodes Needed
Adjustable Output from 1.22V to 60V
1µA Quiescent Current in Shutdown
Stable with 0.47µF Output Capacitor
Stable with Aluminum, Tantalum or Ceramic
Capacitors
Reverse-Battery Protection
No Reverse Current Flow from Output
Thermal Limiting
Available in 5-Lead ThinSOTTM and
8-Lead DFN Packages
Other features of the LT3014 include the ability to operate
with very small output capacitors. The regulators are
stable with only 0.47µF on the output while most older
devices require between 10µF and 100µF for stability.
Small ceramic capacitors can be used without the necessary addition of ESR as is common with other regulators.
Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse
current protection.
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APPLICATIO S
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Low Current High Voltage Regulators
Regulator for Battery-Powered Systems
Telecom Applications
Automotive Applications
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6118263, 6144250.
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The device is available as an adjustable device with a 1.22V
reference voltage. The LT3014 regulator is available in the
5-lead ThinSOT and 8-lead DFN packages.
TYPICAL APPLICATIO
Dropout Voltage
400
5V Supply with Shutdown
VIN
5.4V TO
80V
OUT
LT3014
3.92M
VOUT
5V
20mA
0.47µF
1µF
SHDN
GND
ADJ
1.27M
3014 TA01
VSHDN OUTPUT
<0.3V
OFF
>2.0V
ON
DROPOUT VOLTAGE (mV)
IN
350
300
250
200
150
100
50
0
0
2
4
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
3014 TA02
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LT3014
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ABSOLUTE
RATI GS (Note 1)
IN Pin Voltage, Operating ................................. ±80V
Transient (2ms Survival, LT3014HV) .............. +100V
OUT Pin Voltage ............................................... ±60V
IN to OUT Differential Voltage ........................... ±80V
ADJ Pin Voltage .................................................. ±7V
SHDN Pin Input Voltage ................................... ±80V
Output Short-Circuit Duration ..................... Indefinite
Storage Temperature Range
ThinSOT Package......................... –65°C to 150°C
DFN Package ............................... –65°C to 125°C
Operating Junction Temperature Range
(Notes 3, 10, 11) ......................... –40°C to 125°C
Lead Temperature, SOT-23
(Soldering, 10 sec) ..................................... 300°C
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
TOP VIEW
IN 1
5 OUT
GND 2
SHDN 3
4 ADJ
S5 PACKAGE
5-LEAD PLASTIC SOT-23
TJMAX = 125°C, θJA = 150°C/ W
θJC = 25°C/ W MEASURED AT PIN 2.
SEE APPLICATIONS INFORMATION SECTION.
ORDER PART NUMBER
LT3014ES5
LT3014HVES5
S5 PART MARKING
LTBMF
LTBRS
OUT
1
8
IN
ADJ
2
7
NC
NC
3
6
NC
GND
4
5
SHDN
9
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
EXPOSED PAD IS GND (PIN 9)
MUST BE SOLDERED TO PCB
TJMAX = 125°C, θJA = 40°C/ W
θJC = 10°C/ W MEASURED AT PIN 9.
ORDER PART NUMBER
LT3014EDD
LT3014HVEDD
DD PART MARKING
LBMG
LBRT
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C.
PARAMETER
CONDITIONS
MIN
Minimum Input Voltage
ILOAD = 20mA
●
ADJ Pin Voltage
(Notes 2, 3)
VIN = 3.3V, ILOAD = 100µA
3.3V < VIN < 80V, 100µA < ILOAD < 20mA
●
Line Regulation
∆VIN = 3.3V to 80V, ILOAD = 100µA (Note 2)
●
Load Regulation
VIN = 3.3V, ∆ILOAD = 100µA to 20mA (Note 2)
VIN = 3.3V, ∆ILOAD = 100µA to 20mA
●
1.200
1.180
TYP
MAX
UNITS
3
3.3
V
1.220
1.220
1.240
1.260
V
V
1
10
mV
13
25
40
mV
mV
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LT3014
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C.
PARAMETER
CONDITIONS
Dropout Voltage
VIN = VOUT(NOMINAL) (Notes 4, 5)
ILOAD = 100µA
ILOAD = 100µA
●
ILOAD = 1mA
ILOAD = 1mA
●
ILOAD = 10mA
ILOAD = 10mA
●
ILOAD = 20mA
ILOAD = 20mA
●
ILOAD = 0mA
ILOAD = 100µA
ILOAD = 1mA
ILOAD = 10mA
ILOAD = 20mA
●
●
●
●
●
GND Pin Current
VIN = VOUT(NOMINAL)
(Notes 4, 6)
MIN
Output Voltage Noise
COUT = 0.47µF, ILOAD = 20mA, BW = 10Hz to 100kHz
ADJ Pin Bias Current
(Note 7)
Shutdown Threshold
VOUT = Off to On
VOUT = On to Off
●
●
SHDN Pin Current
(Note 8)
VSHDN = 0V
VSHDN = 6V
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
MAX
UNITS
120
180
250
mV
mV
200
270
360
mV
mV
300
350
450
mV
mV
350
410
570
mV
mV
7
12
40
250
650
20
30
100
450
1000
µA
µA
µA
µA
µA
µVRMS
115
4
10
nA
1.3
1.3
2
V
V
●
●
1
0
4
1
µA
µA
●
1
4
µA
Ripple Rejection
VIN = 7V(Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 20mA
Current Limit
VIN = 7V, VOUT = 0V
VIN = 3.3V, ∆VOUT = –0.1V (Note 2)
●
Input Reverse
Leakage Current
VIN = –80V, VOUT = 0V
●
Reverse Output Current
(Note 9)
VOUT = 1.22V, VIN < 1.22V (Note 2)
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.
Note 2: The LT3014 is tested and specified for these conditions with the
ADJ pin connected to the OUT pin.
Note 3: 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 4: To satisfy requirements for minimum input voltage, the LT3014 is
tested and specified for these conditions with an external resistor divider
(249k bottom, 392k top) for an output voltage of 3.3V. The external
resistor divider adds a 5µA DC load on the output.
Note 5: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage is equal to (VIN – VDROPOUT).
TYP
0.25
60
70
dB
70
mA
mA
25
2
6
mA
4
µA
Note 6: GND pin current is tested with VIN = VOUT (nominal) and a current
source load. This means the device is tested while operating in its dropout
region. This is the worst-case GND pin current. The GND pin current
decreases slightly at higher input voltages.
Note 7: ADJ pin bias current flows into the ADJ pin.
Note 8: SHDN pin current flows out of the SHDN pin.
Note 9: Reverse output current is tested with the IN pin grounded and the
OUT pin forced to the rated output voltage. This current flows into the OUT
pin and out of the GND pin.
Note 10: The LT3014E is guaranteed to meet performance specifications
from 0°C to 125°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
Note 11: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is
active. Continuous operation above the specified maximum operating
junction temperature may impair device reliability.
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LT3014
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TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage
Guaranteed Dropout Voltage
600
500
= TEST POINTS
450
450
400
TJ = 125°C
350
300
TJ = 25°C
250
200
150
100
400
DROPOUT VOLTAGE (mV)
TJ ≤ 125°C
500
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
Dropout Voltage
500
TJ ≤ 25°C
300
200
2
4
0
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
2
4
VSHDN = VIN
8
6
4
VSHDN = 0V
0
– 50 – 25
0
50
75
25
TEMPERATURE (°C)
100
125
1.230
1.225
1.220
1.215
1.210
75
50
25
TEMPERATURE (°C)
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
4
125
GND PIN CURRENT (µA)
8
9
10
VSHDN = 0V
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
3014 G05
500
400
300
3014 G06
1.6
1.4
1.2
1.0
0.8
0.6
200
0.4
100
0.2
2
4
10
1.8
600
0
9
SHDN Pin Threshold
700
0
8
2.0
VIN = 3.3V
900 TJ = 25°C
= 1.22V
V
800 OUT
RL = 1.22k
IL = 1mA*
100
VSHDN = VIN
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GND Pin Current vs ILOAD
RL = 122Ω
IL = 10mA*
200
100
1000
500
300
8
0
800
400
10
1.200
– 50 – 25
TJ = 25°C
900 *FOR VOUT = 1.22V
600
12
2
GND Pin Current
125
TJ = 25°C
14 RL = ∞
VOUT = 1.22V
1.205
1000
RL = 61Ω
IL = 20mA*
100
16
IL = 100µA
3014 G04
700
50
25
0
75
TEMPERATURE (°C)
Quiescent Current
QUIESCENT CURRENT (µA)
10
ADJ PIN VOLTAGE (V)
QUIESCENT CURRENT (µA)
IL = 100µA
3014 G03
1.235
2
GND PIN CURRENT (µA)
150
ADJ Pin Voltage
VIN = 6V
RL = ∞
IL = 0
0
IL = 1mA
200
3014 G02
1.240
12
0
250
0
–50 –25
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
SHDN PIN THRESHOLD (V)
0
Quiescent Current
14
IL = 10mA
300
50
0
3014 G01
16
IL = 20mA
100
100
50
0
400
350
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
3014 G09
3014 G07
3014 G08
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LT3014
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TYPICAL PERFOR A CE CHARACTERISTICS
SHDN Pin Current
SHDN Pin Current
1.6
1.2
VSHDN = 0V
1.4 CURRENT FLOWS
OUT OF SHDN PIN
0.8
0.6
0.4
0.2
1.2
1.0
0.8
0.6
0.4
0
2.5 3
1 1.5 2
SHDN PIN VOLTAGE (V)
0.5
3.5
0
– 50 – 25
4
0
50
75
25
TEMPERATURE (°C)
3014 G10
50
40
30
20
0
70
60
50
40
30
100
25
20
10
100
125
3014 G16
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
VIN = 7V + 50mVRMS RIPPLE
IL = 20mA
70
66
64
62
60
60
50
40
COUT = 4.7µF
30
20
COUT = 0.47µF
10
0
50
75
25
TEMPERATURE (°C)
10
Input Ripple Rejection
VIN = 7V + 0.5VP-P
70 RIPPLE AT f = 120Hz
IL = 20mA
68
56
– 50 – 25
9
3014 G15
80
58
1
CURRENT FLOWS
INTO OUTPUT PIN
15
125
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
2
50
75
25
TEMPERATURE (°C)
30
Input Ripple Rejection
3
ADJ PIN
ESD CLAMP
35
0
50
25
0
75
TEMPERATURE (°C)
72
VIN = 0V
VOUT = VADJ = 1.22V
0
TJ = 25°C
45 VIN = 0V
= VADJ
V
40 OUT
3014 G14
Reverse Output Current
125
5
3014 G13
4
100
Reverse Output Current
VIN = 7V
VOUT = 0V
0
–50 –25
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
5
50
75
25
TEMPERATURE (°C)
3014 G12
10
6
0
50
20
10
0
– 50 – 25
4
0
– 50 – 25
125
80
CURRENT LIMIT (mA)
CURRENT LIMIT (mA)
90
60
4
6
Current Limit
100
VOUT = 0V
70 TJ = 25°C
REVERSE OUTPUT CURRENT (µA)
100
REVERSE OUTPUT CURRENT (µA)
Current Limit
2
8
3014 G11
80
0
10
2
0.2
0
7
12
ADJ PIN BIAS CURRENT (nA)
SHDN PIN CURRENT (µA)
SHDN PIN CURRENT (µA)
TJ = 25°C
CURRENT FLOWS
1.0 OUT OF SHDN PIN
8
ADJ Pin Bias Current
14
100
125
3014 G17
0
10
100
1k
10k
FREQUENCY (Hz)
100k
1M
3014 G18
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LT3014
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TYPICAL PERFOR A CE CHARACTERISTICS
ILOAD = 20mA
–5
3.0
LOAD REGULATION (mV)
MINIMUM INPUT VOLTAGE (V)
Load Regulation
0
2.5
2.0
1.5
1.0
0.5
Output Noise Spectral Density
∆IL = 100µA TO 20mA
VOUT = 1.22V
OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)
Minimum Input Voltage
3.5
–10
–15
–20
–25
–30
–35
0
–50 –25
25
75
0
50
TEMPERATURE (°C)
100
125
–40
– 50 – 25
0
25
50
75
100
COUT = 0.47µF
IL = 20mA
VOUT = 1.22V
1
0.1
0.01
10
100
TEMPERATURE (°C)
3014 G19
100k
3014 G21
3014 G22
LOAD CURRENT (mA)
OUTPUT VOLTAGE
DEVIATION (V)
Transient Response
VOUT
200µV/DIV
1ms/DIV
1k
10k
FREQUENCY (Hz)
3014 G20
10Hz to 100kHz Output Noise
COUT = 0.47µF
IL = 20mA
VOUT = 1.22V
125
10
0.04
0.02
0
VIN = 7V
VOUT = 5V
CIN = COUT = 0.47µF CERAMIC
∆ILOAD = 1mA TO 5mA
–0.02
–0.04
6
4
2
0
0
200
600
400
TIME (µs)
800
1000
3014 G23
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PI FU CTIO S
(SOT-23 Package/DD Package)
IN (Pin 1/Pin 8): Input. Power is supplied to the device
through the IN pin. A bypass capacitor is required on this
pin if the device is more than six inches away from the main
input filter capacitor. In general, the output impedance of
a battery rises with frequency, so it is advisable to include
a bypass capacitor in battery-powered circuits. A bypass
capacitor in the range of 0.1µF to 10µF is sufficient. The
LT3014 is designed to withstand reverse voltages on the
IN pin with respect to ground and the OUT pin. In the case
of a reversed input, which can happen if a battery is
plugged in backwards, the LT3014 will act as if there is a
diode in series with its input. There will be no reverse
current flow into the LT3014 and no reverse voltage will
appear at the load. The device will protect both itself and
the load.
GND (Pin 2/Pins 4, 9): Ground.
SHDN (Pin 3/Pin 5): Shutdown. The SHDN pin is used to
put the LT3014 into a low power shutdown state. The
output will be off when the SHDN pin is pulled low. The
SHDN pin can be driven either by 5V logic or opencollector logic with a pull-up resistor. The pull-up resistor
is only required to supply the pull-up current of the opencollector gate, normally several microamperes. If unused,
the SHDN pin must be tied to IN or to a logic high.
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LT3014
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PI FU CTIO S
(SOT-23 Package/DD Package)
ADJ (Pin 4/Pin 2): Adjust. This is the input to the error
amplifier. This pin is internally clamped to ±7V. It has a
bias current of 4nA which flows into the pin (see curve of
ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin voltage is 1.22V
referenced to ground, and the output voltage range is
1.22V to 60V.
OUT (Pin 5/Pin 1): Output. The output supplies power to
the load. A minimum output capacitor of 0.47µF is required to prevent oscillations. Larger output capacitors
will be required for applications with large transient loads
to limit peak voltage transients. See the Applications
Information section for more information on output capacitance and reverse output characteristics.
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APPLICATIO S I FOR ATIO
The LT3014 is a 20mA high voltage low dropout regulator
with micropower quiescent current and shutdown. The
device is capable of supplying 20mA at a dropout voltage
of 350mV. The low operating quiescent current (7µA)
drops to 1µA in shutdown. In addition to the low quiescent
current, the LT3014 incorporates several protection features which make it ideal for use in battery-powered
systems. The device is protected against both reverse
input and reverse output voltages. In battery backup
applications where the output can be held up by a backup
battery when the input is pulled to ground, the LT3014 acts
like it has a diode in series with its output and prevents
reverse current flow.
Adjustable Operation
The LT3014 has an output voltage range of 1.22V to 60V.
The output voltage is set by the ratio of two external
resistors as shown in Figure 2. The device servos the
output to maintain the voltage at the adjust pin at 1.22V
referenced to ground. The current in R1 is then equal to
1.22V/R1 and the current in R2 is the current in R1 plus
the ADJ pin bias current. The ADJ pin bias current, 4nA
at 25°C, flows through R2 into the ADJ pin. The output
voltage can be calculated using the formula in Figure 1.
The value of R1 should be less than 1.62M 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. The device is tested
and specified with the ADJ pin tied to the OUT pin and a
5µA DC load (unless otherwise specified) for an output
voltage of 1.22V. Specifications for output voltages greater
than 1.22V will be proportional to the ratio of the desired
output voltage to 1.22V (VOUT/1.22V). For example, load
regulation for an output current change of 1mA to 20mA
is –13mV typical at VOUT = 1.22V. At VOUT = 12V, load
regulation is:
(12V/1.22V) • (–13mV) = –128mV
IN
VIN
VOUT
OUT
R2
LT3014
+
ADJ
GND
R1
( )
3014 F01
VOUT = 1.22V • 1 + R2 + (IADJ)(R2)
R1
VADJ = 1.22V
IADJ = 4nA AT 25°C
OUTPUT RANGE = 1.22V TO 60V
Figure 1. Adjustable Operation
Output Capacitance and Transient Response
The LT3014 is designed to be stable with a wide range of
output capacitors. The ESR of the output capacitor affects
stability, most notably with small capacitors. A minimum
output capacitor of 0.47µF with an ESR of 3Ω or less is
recommended to prevent oscillations. The LT3014 is a
micropower device and output transient response will be
a function of output capacitance. Larger values of output
capacitance decrease the peak deviations and provide
improved transient response for larger load current
changes. Bypass capacitors, used to decouple individual
components powered by the LT3014, will increase the
effective output capacitor value.
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LT3014
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APPLICATIO S I FOR ATIO
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 Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 2 and 3. When
used with a 5V regulator, a 10µF Y5V capacitor can exhibit
an effective value as low as 1µF to 2µF 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 available in higher values.
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,
20
similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor the stress can be
induced by vibrations in the system or thermal transients.
Thermal Considerations
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:
1. Output current multiplied by the input/output voltage
differential: IOUT • (VIN – VOUT) and,
2. GND 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 Characteristics. Power dissipation will be equal to the sum of the two
components listed above.
40
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
20
X5R
CHANGE IN VALUE (%)
CHANGE IN VALUE (%)
0
–20
–40
–60
Y5V
–80
–100
0
X5R
–20
–40
Y5V
–60
–80
0
2
4
8
6
10 12
DC BIAS VOLTAGE (V)
14
16
3014 F02
Figure 2. Ceramic Capacitor DC Bias Characteristics
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–100
50
25
75
–50 –25
0
TEMPERATURE (°C)
100
125
3014 F03
Figure 3. Ceramic Capacitor Temperature Characteristics
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APPLICATIO S I FOR ATIO
The LT3014 regulator has internal thermal limiting designed to protect the device during overload conditions.
For continuous normal conditions the maximum junction
temperature rating of 125°C must not be exceeded. It is
important to give careful consideration to all sources of
thermal resistance from junction to ambient. Additional
heat sources mounted nearby must also be considered.
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Copper board stiffeners and plated
through-holes can also be used to spread the heat generated by power devices.
The following table lists thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 3/32" FR-4 board with one ounce
copper.
Table 1. SOT-23 Measured Thermal Resistance
COPPER AREA
TOPSIDE
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500 sq mm
2500 sq mm
2500 sq mm
125°C/W
1000 sq mm
2500 sq mm
2500 sq mm
125°C/W
225 sq mm
2500 sq mm
2500 sq mm
130°C/W
100 sq mm
2500 sq mm
2500 sq mm
135°C/W
50 sq mm
2500 sq mm
2500 sq mm
150°C/W
Continuous operation at large input/output voltage differentials and maximum load current is not practical due to
thermal limitations. Transient operation at high input/
output differentials is possible. The approximate thermal
time constant for a 2500sq mm 3/32" FR-4 board with
maximum topside and backside area for one ounce copper
is 3 seconds. This time constant will increase as more
thermal mass is added (i.e. vias, larger board, and other
components).
For an application with transient high power peaks, average power dissipation can be used for junction temperature calculations as long as the pulse period is significantly
less than the thermal time constant of the device and
board.
Calculating Junction Temperature
Example 1: Given an output voltage of 5V, an input voltage
range of 24V to 30V, an output current range of 0mA to
20mA, 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) = 20mA
Table 2. DFN Measured Thermal Resistance
COPPER AREA
TOPSIDE
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500 sq mm
2500 sq mm
2500 sq mm
40°C/W
1000 sq mm
2500 sq mm
2500 sq mm
45°C/W
225 sq mm
2500 sq mm
2500 sq mm
50°C/W
100 sq mm
2500 sq mm
2500 sq mm
62°C/W
For the DFN package, the thermal resistance junction-tocase (θJC), measured at the exposed pad on the back of the
die, is 16°C/W.
VIN(MAX) = 30V
IGND at (IOUT = 20mA, VIN = 30V) = 0.55mA
So:
P = 20mA • (30V – 5V) + (0.55mA • 30V) = 0.52W
The thermal resistance for the DFN package will be in the
range of 40°C/W to 62°C/W depending on the copper area.
So the junction temperature rise above ambient will be
approximately equal to:
0.52W • 50°C/W = 26°C
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9
LT3014
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W
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APPLICATIO S I FOR ATIO
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
TJMAX = 50°C + 26°C = 76°C
Example 2: Given an output voltage of 5V, an input voltage
of 48V that rises to 72V for 5ms(max) out of every 100ms,
and a 5mA load that steps to 20mA for 50ms out of every
250ms, what is the junction temperature rise above ambient? Using a 500ms period (well under the time constant
of the board), power dissipation is as follows:
P1(48V in, 5mA load) = 5mA • (48V – 5V)
+ (100µA • 48V) = 0.22W
P2(48V in, 20mA load) = 20mA • (48V – 5V)
+ (0.55mA • 48V) = 0.89W
P3(72V in, 5mA load) = 5mA • (72V – 5V)
+ (100µA • 72V) = 0.34W
P4(72V in, 20mA load) = 20mA • (72V – 5V)
+ (0.55mA • 72V) = 1.38W
Operation at the different power levels is as follows:
76% operation at P1, 19% for P2, 4% for P3, and
1% for P4.
PEFF = 76%(0.22W) + 19%(0.89W) + 4%(0.34W)
+ 1%(1.38W) = 0.36W
With a thermal resistance in the range of 40°C/W to
62°C/W, this translates to a junction temperature rise
above ambient of 20°C.
Protection Features
The LT3014 incorporates several protection features which
make it ideal for use in battery-powered circuits. In addition to the normal protection features associated with
monolithic regulators, such as current limiting and thermal limiting, the device is protected against reverse-input
voltages, and reverse voltages from output to input.
Current limit protection and thermal overload protection
are intended to protect the device against current overload
conditions at the output of the device. For normal operation, the junction temperature should not exceed 125°C.
The input of the device will withstand reverse voltages of
80V. Current flow into the device will be limited to less than
6mA (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
which can be plugged in backward.
The ADJ pin can be pulled above or below ground by as
much as 7V without damaging the device. If the input is left
open circuit or grounded, the ADJ pin will act like an open
circuit when pulled below ground, and like a large resistor
(typically 100k) in series with a diode when pulled above
ground. If the input is powered by a voltage source, pulling
the ADJ pin below the reference voltage will cause the
device to current limit. This will cause the output to go to
an unregulated high voltage. Pulling the ADJ pin above the
reference voltage will turn off all output current.
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10
LT3014
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APPLICATIO S I FOR ATIO
In situations where the ADJ pin is connected to a resistor
divider that would pull the ADJ pin above its 7V clamp
voltage if the output is pulled high, the ADJ pin input
current must be limited to less than 5mA. For example, a
resistor divider is used to provide a regulated 1.5V output
from the 1.22V reference when the output is forced to 60V.
The top resistor of the resistor divider must be chosen to
limit the current into the ADJ pin to less than 5mA when the
ADJ pin is at 7V. The 53V difference between the OUT and
ADJ pins divided by the 5mA maximum current into the
ADJ pin yields a minimum top resistor value of 10.6k.
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 follow
the curve shown in Figure 4. The rise in reverse output
current above 7V occurs from the breakdown of the 7V
clamp on the ADJ pin. With a resistor divider on the
regulator output, this current will be reduced depending
on the size of the resistor divider.
When the IN pin of the LT3014 is forced below the OUT pin
or the OUT pin is pulled above the IN pin, input current will
typically drop to less than 2µA. This can happen if the input
of the LT3014 is connected to a discharged (low voltage)
battery and the output is held up by either a backup battery
or a second regulator circuit. The state of the SHDN pin will
have no effect on the reverse output current when the
output is pulled above the input.
REVERSE OUTPUT CURRENT (µA)
50
TJ = 25°C
45 VIN = 0V
= VADJ
V
40 OUT
ADJ PIN
ESD CLAMP
35
30
25
20
CURRENT FLOWS
INTO OUTPUT PIN
15
10
5
0
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
10
3014 F04
Figure 4. Reverse Output Current
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11
LT3014
U
TYPICAL APPLICATIO S
5V Buck Converter with Low Current Keep Alive Backup
D2
D1N914
6
VIN
5.5V*
TO 60V
C2
0.33µF
BOOST
4
C3
4.7µF
100V
CERAMIC
VIN
SW
2
14
BIAS
SHDN
FB
SYNC
10
R1
15.4k
12
R2
4.99k
VC
GND
VOUT
5V
1A/20mA
D1
10MQ060N
LT1766
15
L1†
15µH
+
C1
100µF 10V
SOLID
TANTALUM
1, 8, 9, 16 11
CC
1nF
IN
OPERATING
CURRENT
SHDN
LOW HIGH
3014 TA03
OUT
LT3014
3.92M
ADJ
GND
1.27M
* FOR INPUT VOLTAGES BELOW 7.5V,
SOME RESTRICTIONS MAY APPLY
†
INCREASE L1 TO 30µH FOR LOAD
CURRENTS ABOVE 0.6A AND TO
60µH ABOVE 1A
Buck Converter
Efficiency vs Load Current
100
VOUT = 5V
L = 68µH
VIN = 10V
EFFICIENCY (%)
90
VIN = 42V
80
70
60
50
0
0.25
0.75
1.00
0.50
LOAD CURRENT (A)
1.25
3014 TA04
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12
LT3014
U
TYPICAL APPLICATIO S
LT3014 Automotive Application
VIN
12V
(LATER 42V)
IN
+
1µF
NO PROTECTION
DIODE NEEDED!
OUT
LT3014
R1
1µF
ADJ
SHDN
GND
R2
LOAD: CLOCK,
SECURITY SYSTEM
ETC
OFF ON
LT3014 Telecom Application
VIN
48V
(72V TRANSIENT)
IN
OUT
LT3014
1µF
ADJ
SHDN
+
R1 NO PROTECTION
DIODE NEEDED!
GND
1µF
R2
OFF ON
LOAD:
SYSTEM MONITOR
ETC
–
BACKUP
BATTERY
3014 TA05
Constant Brightness for Indicator LED over Wide Input Voltage Range
RETURN
IN
1µF
OFF ON
OUT
LT3014
SHDN
1µF
ADJ
GND
–48V
ILED = 1.22V/RSET
–48V CAN VARY FROM –3.3V TO –80V
RSET
3014 TA06
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13
LT3014
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PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1.90 BSC
S5 TSOT-23 0302 REV B
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14
LT3014
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PACKAGE DESCRIPTIO
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 ±0.05
3.5 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
5
3.00 ±0.10
(4 SIDES)
0.38 ± 0.10
8
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
(DD) DFN 1203
0.200 REF
0.75 ±0.05
0.00 – 0.05
4
0.25 ± 0.05
1
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
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
3014fb
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LT3014
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1129
700mA, Micropower, LDO
VIN: 4.2V to 30V, VOUT(MIN) = 3.75V, VDO = 0.4V, IQ = 50µA, ISD = 16µA,
DD, SOT-223, S8, TO220, TSSOP-20 Packages
LT1175
500mA, Micropower Negative LDO
VIN: –20V to –4.3V, VOUT(MIN) = –3.8V, VDO = 0.50V, IQ = 45µA, ISD = 10µA,
DD, SOT-223, S8 Packages
LT1185
3A, Negative LDO
VIN: –35V to –4.2V, VOUT(MIN) = –2.40V, VDO = 0.80V, IQ = 2.5mA, ISD <1µA,
TO220-5 Package
LT1761
100mA, Low Noise Micropower, LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 20µA, ISD <1µA,
ThinSOT Package
LT1762
150mA, Low Noise Micropower, LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 25µA, ISD <1µA,
MS8 Package
LT1763
500mA, Low Noise Micropower, LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 30µA, ISD <1µA,
S8 Package
LT1764/LT1764A 3A, Low Noise, Fast Transient Response, LDO
VIN: 2.7V to 20V, VOUT(MIN) = 1.21V, VDO = 0.34V, IQ = 1mA, ISD <1µA,
DD, TO220 Packages
LTC1844
150mA, Very Low Dropout LDO
VIN: 1.6V to 6.5V, VOUT(MIN) = 1.25V, VDO = 0.08V, IQ = 40µA, ISD <1µA,
ThinSOT Package
LT1962
300mA, Low Noise Micropower, LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.27V, IQ = 30µA, ISD <1µA,
MS8 Package
LT1963/LT1963A 1.5A, Low Noise, Fast Transient Response, LDO
VIN: 2.1V to 20V, VOUT(MIN) = 1.21V, VDO = 0.34V, IQ = 1mA, ISD <1µA,
DD, TO220, SOT Packages
LT1964
200mA, Low Noise Micropower, Negative LDO
VIN: –1.9V to –20V, VOUT(MIN) = –1.21V, VDO = 0.34V, IQ = 30µA, ISD = 3µA,
ThinSOT Package
LT3010
50mA, 80V, Low Noise Micropower, LDO
VIN: 3V to 80V, VOUT(MIN) = 1.28V, VDO = 0.3V, IQ = 30µA, ISD <1µA,
MS8E Package
LT3020
100mA, Low VIN, Low VOUT Micropower, VLDO
VIN: 0.9V to 10V, VOUT(MIN) = 0.20V, VDO = 0.15V, IQ = 120µA, ISD <1µA,
DFN, MS8 Packages
LT3023
Dual 100mA, Low Noise Micropower, LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 40µA, ISD <1µA,
DFN, MS10 Packages
LT3024
Dual 100mA/500mA, Low Noise Micropower,
LDO
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 60µA, ISD <1µA,
DFN, TSSOP-16E Packages
LT3027
Dual 100mA, Low Noise LDO with Independent
Inputs
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 40µA, ISD <1µA,
DFN, MS10E Packages
LT3028
Dual 100mA/500mA, Low Noise LDO with
Independent Inputs
VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.30V, IQ = 60µA, ISD <1µA,
DFN, TSSOP-16E Packages
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16
Linear Technology Corporation
LT/LWI 0706 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005
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