4
LT1521/LT1521-3
LT1521-3.3/LT1521-5
1521335fb
ELECTRICAL CHARACTERISTICS
TEMPERATURE (°C)
–50
DROPOUT VOLTAGE (V)
0.7
25
LT1521 • TPC02
0.4
0.2
–25 0 50
0.1
0
0.8
0.6
0.5
0.3
75 100 125
I
LOAD
= 1mA
I
LOAD
= 50mA
I
LOAD
= 150mA
I
LOAD
= 300mA
I
LOAD
= 100mA
TEMPERATURE (°C)
–50
QUIESCENT CURRENT (µA)
15.0
12.5
10.0
7.5
5.0
2.5
0
25 75
LT1521 • TPC03
–25 0
50 100 125
V
IN
= 6V
R
L
= ∞
I
LOAD
= 0
V
SHDN
= OPEN
V
SHDN
= 0V
Quiescent Current
Guaranteed Dropout Voltage
OUTPUT CURRENT (mA)
0
DROPOUT VOLTAGE (V)
150
250
LT1521 • TPC01
50 100 200
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
300
T
J
≤ 125°C
T
J
≤ 25°C
= TEST POINTS
Dropout Voltage
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Reverse Leakage Current V
IN
= –20V, V
OUT
= 0V ● 1.0 mA
Reverse Output Current (Note 11) LT1521-3 V
OUT
= 3V, V
IN
< 3V, T
J
= 25°C510µA
LT1521-3.3 V
OUT
= 3.3V, V
IN
< 3.3V, T
J
= 25°C510µA
LT1521-5 V
OUT
= 5V, V
IN
< 5V, T
J
= 25°C510µA
LT1521 (Note 5) V
OUT
= 3.8V, V
IN
< 3.75V, T
J
= 25°C510µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The shutdown pin input voltage rating is required for a low
impedance source. Internal protection devices connected to the shutdown
pin will turn on and clamp the pin to approximately 7V or –0.6V. This
range allows the use of 5V logic devices to drive the pin directly. For high
impedance sources or logic running on supply voltages greater than 5.5V,
the maximum current driven into the shutdown pin must be limited to less
than 5mA.
Note 3: For junction temperatures greater than 110°C, a minimum load of
1mA is recommended. For T
J
> 110°C and I
OUT
< 1mA, output voltage
may increase by 1%.
Note 4: 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 5: The LT1521 (adjustable version) is tested and specified with the
adjust pin connected to the output pin.
Note 6: Dropout voltage is the minimum input/output voltage required to
maintain regulation at the specified output current. In dropout the output
voltage will be equal to: (V
IN
– V
DROPOUT
)
Note 7: Ground pin current is tested with V
IN
= V
OUT
(nominal) and a
current source load. This means the device is tested while operating in its
dropout region. This is the worst-case ground pin current. The ground pin
current will decrease slightly at higher input voltages.
Note 8: Adjust pin bias current flows into the adjust pin.
Note 9: Shutdown pin current at V
SHDN
= 0V flows out of the shutdown
pin.
Note 10: Quiescent current in shutdown is equal to the total sum of the
shutdown pin current (2µA) and the ground pin current (4µA).
Note 11: Reverse output current is tested with the input pin grounded and
the output pin forced to the rated output voltage. This current flows into
the output pin and out of the ground pin.
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
