LP3981
Micropower, 300mA Ultra Low-Dropout CMOS Voltage
Regulator
General Description
The LP3981's performance is optimized for battery powered
systems to deliver ultra low noise, extremely low dropout
voltage and low quiescent current. Regulator ground current
increases only slightly in dropout, further prolonging the
battery life.
Power supply rejection is better than 60 dB at low frequen-
cies. This high power supply rejection is maintained down to
lower input voltage levels common to battery operated cir-
cuits.
The device is ideal for mobile phone and similar battery
powered wireless applications. It provides up to 300 mA,
from a 2.5V to 6V input, consuming less than 1A in disable
mode.
The LP3981 is available in MSOP-8 package. For LP3981 in
LLP-6 package, contact NSC sales offices. Performance is
specified for -40C to +125C temperature range. The de-
vice available in the following output voltages; 2.5V, 2.7V,
2.8V, 2.83V, 3.0V, 3.03V and 3.3V as standard. Other output
options can be made available, please contact your local
NSC sales office.
Key Specifications
n
2.5 to 6.0V input range
n
300mA guaranteed output
n
60dB PSRR at 1kHz
n
1A quiescent current when shut down
n
Fast Turn-On time: 120 s (typ.) with C
BYPASS
= 0.01uF
n
132mV typ dropout with 300mA load
n
35Vrms output noise over 10Hz to 100kHz
n
-40 to +125C junction temperature range for operation
n
2.5V, 2.7V, 2.8V, 2.83V, 3.0V, 3.03V, and 3.3V outputs
standard
Features
n
Small, space saving MSOP-8
n
Low Thermal Resistance in LLP-6 package gives
excellent power capability
n
Logic controlled enable
n
Stable with ceramic and high quality tantalum capacitors
n
Fast turn-on
n
Thermal shutdown and short-circuit current limit
Applications
n
CDMA cellular handsets
n
Wideband CDMA cellular handsets
n
GSM cellular handsets
n
Portable information appliances
n
Tiny 3.3V
5% to 2.5V, 300mA converter
Typical Application Circuit
20020302
Note: Pin Numbers in parenthesis indicate LLP-6 package.
March 2003
LP3981
Micropower
,
300mA
Ultra
Low-Dropout
CMOS
V
oltage
Regulator
2003 National Semiconductor Corporation
DS200203
www.national.com
Block Diagram
20020301
Pin Descriptions
Name
MSOP-8
LLP-6
Function
V
EN
7
6
Enable Input Logic, Enable High
GND
5
4
Common Ground
V
OUT
1
1
Output Voltage of the LDO
V
IN
2
2
Input Voltage of the LDO
Bypass
6
5
Optional bypass capacitor for noise
reduction
V
OUT-SENSE
4
3
Output. Voltage Sense Pin. Should
be connected to V
OUT
for proper
operation.
N.C
3, 8
Connection Diagrams
MSOP-8 Package
20020307
Top View
See NS Package Number MUA008AE
LLP-6 Package
20020370
Top View
See NS Package Number LDC06D
LP3981
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Ordering Information
For LLP-6 Package
Output
Voltage (V)
Grade
LP3981 Supplied as 1000
Units, Tape and Reel
LP3981 Supplied as 4500
Units, Tape and Reel
Package Marking
2.5
STD
LP3981ILD-2.5
LP3981ILDX-2.5
LO1UB
2.7
STD
LP3981ILD-2.7
LP3981ILDX-2.7
LO1VB
2.8
STD
LP3981ILD-2.8
LP3981ILDX-2.8
LO1ZB
2.83
STD
LP3981ILD-2.83
LP3981ILDX-2.83
L01SB
3.0
STD
LP3981ILD-3.0
LP3981ILDX-3.0
L017B
3.03
STD
LP3981ILD-3.03
LP3981ILDX-3.03
LO1YB
3.3
STD
LP3981ILD -3.3
LP3981ILDX-3.3
LO1XB
For MSOP-8 Package
Output
Voltage (V)
Grade
LP3981 Supplied as 1000
Units, Tape and Reel
LP3981 Supplied as 3500
Units, Tape and Reel
Package Marking
2.5
STD
LP3981IMM-2.5
LP3981IMMX-2.5
LFKB
2.7
STD
LP3981IMM-2.7
LP3981IMMX-2.7
LFLB
2.8
STD
LP3981IMM-2.8
LP3981IMMX-2.8
LFTB
2.83
STD
LP3981IMM-2.83
LP3981IMMX-2.83
LDUB
3.0
STD
LP3981IMM-3.0
LP3981IMMX-3.0
LF3B
3.03
STD
LP3981IMM-3.03
LP3981IMMX-3.03
LFPB
3.3
STD
LP3981IMM-3.3
LP3981IMMX-3.3
LFNB
*Please contact factory regarding the availability of voltage options not listed here.
LP3981
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3
Absolute Maximum Ratings
(Notes 1,
2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V
IN
, V
EN
-0.3 to 6.5V
V
OUT
, V
OUT-SENSE
-0.3 to V
IN
+ 0.3,
Max 6.5V
Junction Temperature
150C
Storage Temperature
-65C to +150C
Lead Temp.
Pad Temp.
Power Dissipation (Note 3)
JA
(MSOP-8)
JA
(LLP-6)
210C/W
50C/W
Maximum Power Dissipation at 25C
MSOP-8
LLP-6
595mW
2.5W
ESD Rating(Note 4)
Human Body Model
Machine Model
2kV
200V
Operating Ratings
(Notes 1, 2)
V
IN
2.7 to 6V
V
EN
0 to V
IN
Junction Temperature
-40C to +125C
Maximum Power Dissipation (Note 5)
MSOP-8
LLP-6
476mW
2.0W
Electrical Characteristics
Unless otherwise specified: V
EN
= 1.2V, V
IN
= V
OUT
+ 0.5V, C
IN
= 2.2 F, C
BP
= 0.033 F, I
OUT
= 1mA, C
OUT
= 2.2 F. Typi-
cal values and imits appearing in standard typeface are for T
J
= 25C. Limits appearing in boldface type apply over the entire
junction temperature range for operation, -40C to +125C. (Notes 6, 7)
Symbol
Parameter
Conditions
Typ
Limit
Units
Min
Max
V
OUT
Output Voltage
Tolerance
-2
-3
2
3
% of
V
OUT(nom)
Line Regulation Error
V
IN
= V
OUT
+ 0.5V to 6.0V, T
A
<
+85C
0.005
-0.1
0.1
%/V
V
IN
= V
OUT
+ 0.5V to 6.0V, T
J
125C
-0.2
0.2
%/V
Load Regulation Error
(Note 8)
I
OUT
= 1 mA to 300 mA
0.0003
0.005
%/mA
PSRR
Power Supply Rejection Ratio
(Note 10)
V
IN
= V
OUT(nom)
+ 1V,
f = 1 kHz,
I
OUT
= 50 mA (Figure 2)
50
dB
V
IN
= V
OUT(nom)
+ 1V,
f = 10 kHz,
I
OUT
= 50 mA (Figure 2)
55
I
Q
Quiescent Current
V
EN
= 1.2V, I
OUT
= 1 mA
70
120
A
V
EN
= 1.2V, I
OUT
= 1 to 300 mA,
V
OUT
= 2.5V(Note 12)
170
210
V
EN
= 0.4V
0.003
1.5
Dropout Voltage (Note 9)
I
OUT
= 1 mA
0.5
5
mV
I
OUT
= 200 mA
88
133
I
OUT
= 300 mA
132
200
I
SC
Short Circuit Current Limit
Output Grounded
(Steady State)
600
mA
e
n
Output Noise Voltage
BW = 10 Hz to 100 kHz,
C
BP
= 0.033F
35
Vrms
TSD
Thermal Shutdown Temperature
160
C
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
A
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
LP3981
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4
Electrical Characteristics
(Continued)
Unless otherwise specified: V
EN
= 1.2V, V
IN
= V
OUT
+ 0.5V, C
IN
= 2.2 F, C
BP
= 0.033 F, I
OUT
= 1mA, C
OUT
= 2.2 F. Typi-
cal values and imits appearing in standard typeface are for T
J
= 25C. Limits appearing in boldface type apply over the entire
junction temperature range for operation, -40C to +125C. (Notes 6, 7)
Symbol
Parameter
Conditions
Typ
Limit
Units
Min
Max
T
ON
Turn-On Time
(Note 10) (Note 11)
C
BYPASS
= 0.033 F
240
350
s
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device
is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical
Characteristics tables.
Note 2: All voltages are with respect to the potential at the GND pin.
Note 3: The figures given for Absolute Maximum Power disipation for the device are calculated using the following equations:
where T
J(MAX)
is the maximum junction temperature, T
A
is the ambient temperature, and
JA
is the junction-to-ambient thermal resistance.
E.g. for the LLP package
JA
=50C/W, T
J(MAX)
=150C and using T
A
=25C the maximum power dissipation is found to be 2.5W. The derating factor (-1/
JA
) =
-20mW/C, thus below 25C the power dissipation figure can be increased by 20W per degree, and similarity decreased by this factor for temperatures above 25C
Note 4: The human body model is 100pF discharged through 1.5k
resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each
pin.
Note 5: As for the Maximum Power dissipation, the maximum power in operation is dependant on the ambient temperature. This can be calculated in teh same way
using T
J
=125C, giving 2W as the maximum power dissipation for the LLP package in operation. The same derating factor applies.
Note 6: All limits are guaranteed. All electrical characteristics having room-temperature limits are tested during production with T
J
= 25C or correlated using
Statistical Quality Control (SQC) methods. All hot and cold limits are guaranteed by correlating the electrical characteristics to process and temperature variations
and applying statistical process control.
Note 7: The target output voltage, which is labeled V
OUT(nom)
, is the desired voltage option.
Note 8: An increase in the load current results in a slight decrease in the output voltage and vice versa.
Note 9: 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.
Note 10: Guaranteed by design.
Note 11: 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.
Note 12: For V
OUT
>
2.5C, Increase I
Q(MAX)
by 2.5A for every 0.1V increase in V
OUT(NOM)
.
i.e. I
Q(MAX)
= 210 + ((V
OUT(NOM)
- 2.5) * 25)A
Output Capacitor, Recommended Specification
Symbol
Parameter
Conditions
Typ
Limit
Units
Min
Max
C
OUT
Output Capacitor
Capacitance
2.2
22
F
ESR
5
500
m
20020308
FIGURE 1. Line Transient Response Input Perturbation
LP3981
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