Datasheet
LP3981
www.ti.com
SNVS159G –OCTOBER 2001–REVISED MAY 2013
Electrical Characteristics
Unless otherwise specified: V
EN
= 1.2V, V
IN
= V
OUT
+ 0.5V, C
IN
= 2.2 µF, C
BP
= 0.033 µF, I
OUT
= 1mA, C
OUT
= 2.2 µF. Typical
values and imits appearing in standard typeface are for T
J
= 25°C. Limits appearing in boldface type apply over the entire
junction temperature range for operation, −40°C to +125°C.
(1)(2)
Limit
Symbol Parameter Conditions Typ Units
Min Max
Output Voltage −2 2 % of
Tolerance −3 3 V
OUT(nom)
V
IN
= V
OUT
+ 0.5V to 6.0V, T
A
< +85°C 0.005 −0.1 0.1 %/V
ΔV
OUT
Line Regulation Error
V
IN
= V
OUT
+ 0.5V to 6.0V, T
J
≤125°C −0.2 0.2 %/V
Load Regulation Error I
OUT
= 1 mA to 300 mA 0.0003 0.005 %/mA
(3)
V
IN
= V
OUT(nom)
+ 1V, 50
f = 1 kHz,
I
OUT
= 50 mA (Figure 4)
PSRR Power Supply Rejection Ratio
(4)
dB
V
IN
= V
OUT(nom)
+ 1V, 55
f = 10 kHz,
I
OUT
= 50 mA (Figure 4)
I
Q
Quiescent Current V
EN
= 1.2V, I
OUT
= 1 mA 70 120
V
EN
= 1.2V, I
OUT
= 1 to 300 mA, 170 210
µA
V
OUT
= 2.5V
(5)
V
EN
= 0.4V 0.003 1.5
I
OUT
= 1 mA 0.5 5
Dropout Voltage
(6)
I
OUT
= 200 mA 88 133 mV
I
OUT
= 300 mA 132 200
I
SC
Short Circuit Current Limit Output Grounded 600
mA
(Steady State)
e
n
Output Noise Voltage BW = 10 Hz to 100 kHz,
35 µVrms
C
BP
= 0.033µF
Thermal Shutdown Temperature 160 °C
TSD
Thermal Shutdown Hysteresis 20 °C
I
OUT(PK)
Peak Output Current V
OUT
≥ V
OUT
(nom) - 5% 455 300
I
EN
Maximum Input Current at V
EN
V
EN
= 0 and V
IN
0.001 µA
V
IL
Logic Low Input threshold V
IN
= 2.7 to 6.0V 0.4 V
V
IH
Logic High Input threshold V
IN
= 2.7 to 6.0V 1.4 V
T
ON
Turn-On Time
(4) (7)
C
BYPASS
= 0.033 µF 240 350 µs
(1) Min and Max Limits are specified by design, test, or statistical analysis. Typical (Typ.) numbers are not verified, but do represent the
most likely norm.
(2) The target output voltage, which is labeled V
OUT(nom)
, is the desired voltage option.
(3) An increase in the load current results in a slight decrease in the output voltage and vice versa.
(4) Specified by design. Not production tested.
(5) For V
OUT
> 2.5C, Increase I
Q(MAX)
by 2.5µA for every 0.1V increase in V
OUT(NOM)
.i.e. I
Q(MAX)
= 210 + ((V
OUT(NOM)
- 2.5) * 25)µA
(6) Dropout voltage is the input-to-output voltage difference at which the output voltage is 100mV below its nominal value. This specification
does not apply for input voltages below 2.5V.
(7) Turn-on time is time measured between the enable input just exceeding V
IH
and the output voltage just reaching 95% of its nominal
value.
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