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PDF LT3021-1.5 Data sheet ( Hoja de datos )
| Número de pieza | LT3021-1.5 | |
| Descripción | Very Low Dropout Linear Regulator | |
| Fabricantes | Linear | |
| Logotipo |  |
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FEATURES
n VIN Range: 0.9V to 10V
n Dropout Voltage: 160mV Typical
n Output Current: 500mA
n Adjustable Output (VREF = VOUT(MIN) = 200mV)
n Fixed Output Voltages: 1.2V, 1.5V, 1.8V
n Stable with Low ESR, Ceramic Output Capacitors
(3.3μF Minimum)
n 0.2% Load Regulation from 0mA to 500mA
n Quiescent Current: 120μA (Typ)
n 3μA Typical Quiescent Current in Shutdown
n Current Limit Protection
n Reverse-Battery Protection
n No Reverse Current
n Thermal Limiting with Hysteresis
n 16-Pin DFN (5mm × 5mm) and 8-Lead
SO Packages
APPLICATIONS
n Low Current Regulators
n Battery-Powered Systems
n Cellular Phones
n Pagers
n Wireless Modems
TYPICAL APPLICATION
1.8V to 1.5V, 500mA VLDO Regulator
VIN
1.8V
IN OUT
3.3μF
LT3021-1.5
SHDN SENSE
GND
VOUT
1.5V
3.3μF 500mA
3021 TA01
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
500mA, Low Voltage,
Very Low Dropout
Linear Regulator
DESCRIPTION
The LT®3021 is a very low dropout voltage (VLDO™) lin-
ear 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.
L, LT, LTC and LTM 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
3021fc
1
1 page  
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C.
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 LT3021 regulators are tested and specified under pulse load
conditions such that TJ ≈ TA. The LT3021E regulators are 100% tested
at TA = 25°C. Performance at –40°C and 125°C is assured by design,
characterization and correlation with statistical process controls. The
LT3021I regulators are guaranteed over the full –40ºC to 125ºC operating
junction temperature range.
Note 3: 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.
Note 4: Maximum junction temperature limits operating conditions. The
regulated output voltage specification does not apply for all possible
combinations of input voltage and output current. Limit the output current
range if operating at maximum input voltage. Limit the input voltage range
if operating at maximum output current.
Note 5: Typically the LT3021 supplies 500mA output current with a 1V
input supply. The guranteed minimum input voltage for 500mA output
current is 1.10V.
Note 6: The LT3021 is tested and specified for these conditions with an
external resistor divider (20k and 30.1k) setting VOUT to 0.5V. The external
resistor divider adds 10μA of output load current. The line regulation and
load regulation specifications refer to the change in the 0.2V reference
voltage, not the 0.5V output voltage. Specifications for fixed output voltage
devices are referred to the output voltage.
Note 7: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout the
output voltage equals: (VIN – VDROPOUT).
Note 8: GND pin current is tested with VIN = VOUT(NOMINAL) + 0.4V and a
current source load. GND pin current will increase in dropout. See GND pin
current curves in the Typical Performance Characteristics section.
Note 9: Adjust pin bias current flows out of the ADJ pin.
Note 10: Shutdown pin current flows into the SHDN pin.
Note 11: Reverse output current is tested with IN grounded and OUT
forced to the rated output voltage. This current flows into the OUT pin and
out of the GND pin. For fixed voltage devices this includes the current in
the output resistor divider.
Note 12: The LT3021 is tested and specified for these conditions with an
external resistor divider (20k and 100k) setting VOUT to 1.2V. The external
resistor divider adds 10μA of load current.
Note 13: Reverse current is higher for the case of (rated_output) < VOUT
< VIN, because the no-load recovery circuitry is active in this region and is
trying to restore the output voltage to its nominal value.
Note 14: Minimum input voltage is the minimum voltage required by the
control circuit to regulate the output voltage and supply the full 500mA
rated current. This specification is tested at VOUT = 0.5V. At higher output
voltages the minimum input voltage required for regulation will be equal to
the regulated output voltage VOUT plus the dropout voltage.
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
250
225 TJ = 125°C
200
175
150
125
TJ = 25°C
100
75
50
25
0
0 100 200 300 400 500
OUTPUT CURRENT (mA)
3021 G01
Dropout Voltage
250 VOUT = 1.2V
225
IL = 500mA
200
175 IL = 250mA
150
125 IL = 100mA
100
75 IL = 50mA
50 IL = 10mA
25
0
–50 –25
IL = 1mA
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G02
Minimum Input Voltage
1.2 IL = 500mA
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3021 G16
3021fc
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5 Page 
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
APPLICATIONS INFORMATION
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
0
X5R
–20
–40
–60
Y5V
–80
–100
0 2 4 6 8 10 12 14 16
DC BIAS VOLTAGE (V)
3021 F02
Figure 2. Ceramic Capacitor DC Bias Characteristics
40
20
0 X5R
–20
–40
Y5V
–60
–80 BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
–50 –25 0 25 50 75
TEMPERATURE (°C)
100 125
3021 F03
Figure 3. Ceramic Capacitor Temperature Characteristics
amounts of noise. A ceramic capacitor produced Figure
4’s trace in response to light tapping from a pencil. Similar
vibration induced behavior can masquerade as increased
output voltage noise.
No-Load/Light-Load Recovery
A transient load step occurs when the output current changes
from its maximum level to zero current or a very small load
current. The output voltage responds by overshooting until
the regulator lowers the amount of current it delivers to the
new level. The regulator loop response time and the amount
of output capacitance control the amount of overshoot. Once
the regulator has decreased its output current, the current
provided by the resistor divider (which sets VOUT) is the
only current remaining to discharge the output capacitor
from the level to which it overshot. The amount of time it
takes for the output voltage to recover easily extends to
milliseconds with microamperes of divider current and a
few microfarads of output capacitance.
1mV/DIV
VOUT = 1.3V
COUT = 10F
ILOAD = 0
1ms/DIV
3021 F04
Figure 4. Noise Resulting from Tapping on a Ceramic Capacitor
To eliminate this problem, the LT3021 incorporates a
no-load or light-load recovery circuit. This circuit is a
voltage-controlled current sink that significantly improves
the light load transient response time by discharging the
output capacitor quickly and then turning off. The cur-
rent sink turns on when the output voltage exceeds 6%
of the nominal output voltage. The current sink level is
then proportional to the overdrive above the threshold
up to a maximum of approximately 15mA. Consult the
curve in the Typical Performance Characteristics for the
No-Load Recovery Threshold.
If external circuitry forces the output above the no load
recovery circuit’s threshold, the current sink turns on in
an attempt to restore the output voltage to nominal. The
current sink remains on until the external circuitry releases
the output. However, if the external circuitry pulls the output
voltage above the input voltage, or the input falls below
the output, the LT3021 turns the current sink off and shuts
down the bias current/reference generator circuitry.
Thermal Considerations
The LT3021’s power handling capability is limited by
its maximum rated junction temperature of 125°C. The
power dissipated by the device is comprised of two
components:
1. Output current multiplied by the input-to-output voltage
differential: (IOUT)(VIN – VOUT) and
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
GND pin current is found by examining the GND pin current
curves in the Typical Performance Characteristics. Power
dissipation is equal to the sum of the two components
listed above.
3021fc
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT3021-1.5.PDF ] | |
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