LP2985
Electrical Characteristics
(Continued)
Limits in standard typeface are for T
J
= 25˚C. and limits in
boldface type
apply over the full operating temperature range. Un-
less otherwise specified: V
IN
= V
O
(NOM) + 1V, I
L
= 1 mA, C
IN
= 1 µF, C
OUT
= 4.7 µF, V
ON/OFF
= 2V.
LP2985AI-X.X
Symbol
Parameter
Output Noise
Voltage (RMS)
Ripple Rejection
Conditions
BW = 300 Hz to 50 kHz,
C
OUT
= 10 µF
C
BYPASS
= 10 nF
f = 1 kHz, C
BYPASS
= 10 nF
C
OUT
= 10 µF
45
dB
30
µV
Typ
Min
Max
LP2985I-X.X
Min
Max
Units
e
n
I
O
(SC)
I
O
(PK)
Short Circuit Current
Peak Output Current
R
L
= 0 (Steady State)
V
OUT
≥
V
o
(NOM) −5%
400
350
mA
mA
Note 1:
“Absolute Maximum Ratings” indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of its rated operating conditions.
Note 2:
The ESD rating of pins 3 and 4 for the SOT-23 package, or pins 5 and 2 for the micro SMD package, is 1 kV.
Note 3:
The maximum allowable power dissipation is a function of the maximum junction temperature, T
J
(MAX), the junction-to-ambient thermal resistance,
θ
J-A
,
and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperture is calculated using:
Where the value of
θ
J-A
for the SOT-23 package is 220˚C/W in a typical PC board mounting and the micro SMD package is 225˚C/W. Exceeding the maximum
allowable dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown.
Note 4:
For 12V option, output voltage survival: -0.3 to +16V. If used in a dual-supply system where the regulator load is returned to a negative supply, the LP2985
output must be diode-clamped to ground.
Note 5:
The output PNP structure contains a diode between the V
IN
to V
OUT
terminals that is normally reverse-biased. Reversing the polarity from V
IN
to V
OUT
will
turn on this diode.
Note 6:
Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Average Outgoing Quality Level (AOQL).
Note 7:
Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.
Note 8:
The ON/OFF input must be properly driven to prevent possible misoperation. For details, refer to Application Hints.
Note 9:
The LP2985 has foldback current limiting which allows a high peak current when V
OUT
>
0.5V, and then reduces the maximum output current as V
OUT
is
forced to ground (see Typical Performance Characteristics curves).
Note 10:
Exposing the micro SMD device to direct sunlight will cause misoperation. See Application Hints for additional information.
Note 11:
For 12V option, add 50 µA to all ON state quiescent current values.
www.national.com
8
NSC [ NATIONAL SEMICONDUCTOR ]
