LP2980
Electrical Characteristics
(Continued)
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
JA
, and
the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated using:
The value of
θ
JA
for the SOT-23 package is 220˚C/W and the micro SMD package is 320˚C/W. Exceeding the maximum allowable power dissipation will cause ex-
cessive die temperature, and the regulator will go into thermal shutdown.
Note 4:
If used in a dual-supply system where the regulator load is returned to a negative supply, the LP2980 output must be diode-clamped to ground.
Note 5:
The output PNP structure contains a diode between the V
IN
and V
OUT
terminals that is normally reverse-biased. Reversing the polarity from V
IN
to V
OUT
will turn on this diode (see Application Hints).
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 inputs must be properly driven to prevent misoperation. For details, refer to Application Hints.
Note 9:
See Typical Performance Characteristics curves.
Basic Application Circuit
DS012078-2
*
ON/OFF input must be actively terminated. Tie to V
IN
if this function is not to be used.
**
Minimum Output Capacitance is 1 µF to insure stability over full load current range. More capacitance provides superior dynamic performance and additional
stability margin (see Application Hints).
***
Do not make connections to this pin.
5
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