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PDF LT3021-x.x Data sheet ( Hoja de datos )
| Número de pieza | LT3021-x.x | |
| Descripción | Very Low Dropout Linear Regulator | |
| Fabricantes | Linear Technology | |
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LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
500mA, Low Voltage,
Very Low Dropout
Linear Regulator
FEATURES
■ VIN Range: 0.9V to 10V
■ Dropout Voltage: 160mV Typical
■ Output Current: 500mA
■ Adjustable Output (VREF = VOUT(MIN) = 200mV)
■ Fixed Output Voltages: 1.2V, 1.5V, 1.8V
■ Stable with Low ESR, Ceramic Output Capacitors
(3.3µF Minimum)
■ 0.2% Load Regulation from 0mA to 500mA
■ Quiescent Current: 120µA (Typ)
■ 3µA Typical Quiescent Current in Shutdown
■ Current Limit Protection
■ Reverse-Battery Protection
■ No Reverse Current
■ Thermal Limiting with Hysteresis
■ 16-Pin DFN (5mm × 5mm) and 8-Lead
SO Packages
U
APPLICATIO S
■ Low Current Regulators
■ Battery-Powered Systems
■ Cellular Phones
■ Pagers
■ Wireless Modems
TYPICAL APPLICATIO
1.8V to 1.5V, 500mA VLDO Regulator
VIN
1.8V
IN OUT
3.3µF
LT3021-1.5
SHDN SENSE
GND
3021 TA01
VOUT
1.5V
3.3µF 500mA
DESCRIPTIO
The LT®3021 is a very low dropout voltage (VLDOTM) linear
regulator that operates from input supplies down to 0.9V.
This device supplies 500mA of output current with a
typical dropout voltage of 160mV. The LT3021 is ideal for
low input voltage to low output voltage applications,
providing comparable electrical efficiency to that of a
switching regulator.
The LT3021 regulator optimizes stability and transient
response with low ESR, ceramic output capacitors as
small as 3.3µF. Other LT3021 features include 0.05%
typical line regulation and 0.2% typical load regulation. In
shutdown, quiescent current typically drops to 3µA.
Internal protection circuitry includes reverse-battery pro-
tection, current limiting, thermal limiting with hysteresis,
and reverse-current protection. The LT3021 is available as
an adjustable output device with an output range down to
the 200mV reference. Three fixed output voltages, 1.2V,
1.5V and 1.8V, are also available.
The LT3021 regulator is available in the low profile
(0.75mm) 16-pin (5mm × 5mm) DFN package with ex-
posed pad and the 8-lead SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation. VLDO is a
trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
Minimum Input Voltage
1.1 IL = 500mA
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 TA02
3021fa
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
ADJ Pin Voltage
206
204
202
200
198
196
194
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G04
Output Voltage
1.23 ILOAD = 1mA
1.22
1.21
1.20
1.19
1.18
1.17
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G28
Quiescent Current
3.0 VOUT = 1.2V
IL = 0
2.5 TJ = 25°C
2.0
1.5
VSHDN = VIN
1.0
VSHDN = 0V
0.5
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
3021 G03
ADJ Pin Bias Current
25
20
15
10
5
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G11
Output Voltage
1.53
ILOAD = 1mA
1.52
1.51
1.50
1.49
1.48
1.47
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G23
Quiescent Current
3.0
VOUT = 1.5V
IL = 0
2.5 TJ = 25°C
2.0
1.5
VSHDN = VIN
1.0
VSHDN = 0V
0.5
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
3021 G26
Quiescent Current
250 VIN = 6V
225 VOUT = 1.2V
200 IL = 0
175
150 VSHDN = VIN
125
100
75
50
25
0
–50 –25
VSHDN = 0V
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G05
Output Voltage
1.83
ILOAD = 1mA
1.82
1.81
1.80
1.79
1.78
1.77
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G22
Quiescent Current
3.0 VOUT = 1.8V
IL = 0
2.5 TJ = 25°C
2.0
1.5
VSHDN = VIN
1.0
VSHDN = 0V
0.5
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
3021 G27
3021fa
5
5 Page 
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
APPLICATIO S I FOR ATIO
The LT3021 regulator has internal thermal limiting (with
hysteresis) designed to protect the device during overload
conditions. For normal continuous conditions, do not
exceed the maximum junction temperature rating of 125°C.
Carefully consider all sources of thermal resistance from
junction to ambient including other heat sources mounted
in proximity to the LT3021.
The underside of the LT3021 DH package has exposed metal
(14mm2) from the lead frame to where the die is attached.
This allows heat to directly transfer from the die junction
to the printed circuit board metal to control maximum
operating junction temperature. The dual-in-line pin ar-
rangement allows metal to extend beyond the ends of the
package on the topside (component side) of a PCB. Con-
nect this metal to GND on the PCB. The multiple IN and OUT
pins of the LT3021 also assist in spreading heat to the PCB.
The LT3021 S8 package has pin 4 fused with the lead
frame. This also allows heat to transfer from the die to the
printed circuit board metal, therefore reducing the thermal
resistance. Copper board stiffeners and plated through-
holes can also be used to spread the heat generated by
power devices.
The following tables list thermal resistance for several
different board sizes and copper areas for two different
packages. Measurements were taken in still air on 3/32"
FR-4 board with one ounce copper.
Table 1. Measured Thermal Resistance For DH Package
COPPER AREA
THERMAL RESISTANCE
TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)
2500mm2
900mm2
225mm2
100mm2
50mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
30°C/ W
35°C/ W
50°C/ W
55°C/ W
65°C/ W
Table 2. Measured Thermal Resistance For S8 Package
COPPER AREA
TOPSIDE* BACKSIDE
2500mm2 2500mm2
1000mm2 2500mm2
225mm2 2500mm2
100mm2 2500mm2
50mm2 2500mm2
BOARD AREA
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
70°C/ W
70°C/ W
78°C/ W
84°C/ W
96°C/ W
*Device is mounted on topside.
Calculating Junction Temperature
Example: Given an output voltage of 1.2V, an input voltage
range of 1.8V ±10%, an output current range of 1mA to
500mA, and a maximum ambient temperature of 70°C,
what will the maximum junction temperature be for an
application using the DH package?
The power dissipated by the device is equal to:
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
where
IOUT(MAX) = 500mA
VIN(MAX) = 1.98V
IGND at (IOUT = 500mA, VIN = 1.98V) = 10mA
so
P = 500mA(1.98V – 1.2V) + 10mA(1.98V) = 0.41W
The thermal resistance is in the range of 35°C/W to
70°C/W depending on the copper area. So the junction
temperature rise above ambient is approximately equal to:
0.41W(52.5°C/W) = 21.5°C
The maximum junction temperature equals the maximum
junction temperature rise above ambient plus the maxi-
mum ambient temperature or:
TJMAX = 21.5°C + 70°C = 91.5°C
Protection Features
The LT3021 incorporates several protection features that
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 also protects against reverse-
input voltages, reverse-output voltages and reverse
output-to-input voltages.
Current limit protection and thermal overload protection
protect the device against current overload conditions at
the output of the device. For normal operation, do not
exceed a junction temperature of 125°C.
The IN pins of the device withstand reverse voltages of
10V. The LT3021 limits current flow to less than 1µA and
no negative voltage appears at OUT. The device protects
both itself and the load against batteries that are plugged
in backwards.
3021fa
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| PDF Descargar | [ Datasheet LT3021-x.x.PDF ] | |
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