LT1121/LT1121-3.3/LT1121-5
4
1121fg
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 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 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 20mA.
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 LT1121 (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 that 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 sum total of the
shutdown pin current (6µA) and the ground pin current (9µA).
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.
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Ground Pin Current (Note 7) I
LOAD
= 0mA
I
LOAD
= 1mA
I
LOAD
= 10mA
I
LOAD
= 50mA
I
LOAD
= 100mA
I
LOAD
= 150mA
l
l
l
l
l
l
30
90
350
1.5
4
7
50
120
500
2.5
7
14
µA
µA
µA
mA
mA
mA
Adjust Pin Bias Current (Notes 5, 8) T
J
= 25ºC 150 300 nA
Shutdown Threshold V
OUT
= Off to On
V
OUT
= On to Off
l
l
0.25
1.2
0.75
2.8 V
V
Shutdown Pin Current (Note 9) V
SHDN
= 0V
l
6 10 µA
Quiescent Current in Shutdown (Note 10) V
IN
= 6V, V
SHDN
= 0V
l
16 22 µA
Ripple Rejection V
IN
– V
OUT
= 1V (Avg), V
RIPPLE
= 0.5V
P-P
, f
RIPPLE
= 120Hz,
I
LOAD
= 0.1A
50 58 dB
Current Limit V
IN
– V
OUT
= 7V, T
J
= 25ºC 200 500 mA
Input Reverse Leakage Current V
IN
= –20V, V
OUT
= 0V
l
1 mA
Reverse Output Current (Note 11) LT1121-3.3 V
OUT
= 3.3V, V
IN
= 0V
LT1121-5 V
OUT
= 5V, V
IN
= 0V
LT1121 (Note 5) V
OUT
= 3.8V, V
IN
= 0V
16
16
16
25
25
25
µA
µA
µA
