LP3873/LP3876
3A Fast Ultra Low Dropout Linear Regulators
General Description
The LP3873/LP3876 series of fast ultra low-dropout linear
regulators operate from a +2.5V to +7.0V input supply. Wide
range of preset output voltage options are available. These
ultra low dropout linear regulators respond very quickly to
step changes in load, which makes them suitable for low
voltage microprocessor applications. The LP3873/LP3876
are developed on a CMOS process which allows low quies-
cent current operation independent of output load current.
This CMOS process also allows the LP3873/LP3876 to op-
erate under extremely low dropout conditions.
Dropout Voltage: Ultra low dropout voltage; typically 80mV
at 300mA load current and 800mV at 3A load current.
Ground Pin Current: Typically 6mA at 3A load current.
Shutdown Mode: Typically 1A quiescent current when the
shutdown pin is pulled low.
Error Flag: Error flag goes low when the output voltage
drops 10% below nominal value.
SENSE: Sense pin improves regulation at remote loads.
Precision Output Voltage: Multiple output voltage options
are available ranging from 1.8V to 5.0V with a guaranteed
accuracy of
1.5% at room temperature, and
3.0% over all
conditions (varying line, load, and temperature).
Features
n
Ultra low dropout voltage
n
Low ground pin current
n
Load regulation of 0.08%
n
1A quiescent current in shutdown mode
n
Guaranteed output current of 3A DC
n
Available in TO-263 and TO-220 packages
n
Output voltage accuracy
1.5%
n
Error flag indicates output status
n
Sense option improves load regulation
n
Minimum output capacitor requirements
n
Overtemperature/overcurrent protection
n
-40C to +125C junction temperature range
Applications
n
Microprocessor power supplies
n
GTL, GTL+, BTL, and SSTL bus terminators
n
Power supplies for DSPs
n
SCSI terminator
n
Post regulators
n
High efficiency linear regulators
n
Battery chargers
n
Other battery powered applications
Typical Application Circuits
20060501
*SD and ERROR pins must be pulled high through a 10k
pull-up resistor. Connect the ERROR pin to ground if this function is not used. See application hints
for more information.
September 2003
LP3873/LP3876
3A
Fast
Ultra
Low
Dropout
Linear
Regulators
2003 National Semiconductor Corporation
DS200605
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range
-65C to +150C
Lead Temperature
(Soldering, 5 sec.)
260C
ESD Rating (Note 3)
2 kV
Power Dissipation (Note 2)
Internally Limited
Input Supply Voltage (Survival)
-0.3V to +7.5V
Shutdown Input Voltage
(Survival)
-0.3V to 7.5V
Output Voltage (Survival), (Note
6), (Note 7)
-0.3V to +6.0V
I
OUT
(Survival)
Short Circuit Protected
Maximum Voltage for ERROR
Pin
V
IN
Maximum Voltage for SENSE Pin
V
OUT
Operating Ratings
Input Supply Voltage (Note 11)
2.5V to 7.0V
Shutdown Input Voltage
-0.3V to 7.0V
Maximum Operating Current (DC)
3A
Junction Temperature
-40C to +125C
Electrical Characteristics
LP3873/LP3876
Limits in standard typeface are for T
J
= 25C, and limits in boldface type apply over the full operating temperature range.
Unless otherwise specified: V
IN
= V
O(NOM)
+ 1.5V, I
L
= 10 mA, C
OUT
= 10F, V
SD
= 2V.
Symbol
Parameter
Conditions
Typ
(Note 4)
LP3873/6 (Note 5)
Units
Min
Max
V
O
Output Voltage
Tolerance
(Note 8)
V
OUT
+1.5V
V
IN
7.0V
10 mA
I
L
3A
0
-1.5
-3.0
+1.5
+3.0
%
V
OL
Output Voltage Line
Regulation (Note 8)
V
OUT
+ 1.5V
V
IN
7.0V
0.02
0.06
%
V
O
/
I
OUT
Output Voltage Load
Regulation
(Note 8)
10 mA
I
L
3A
0.08
0.14
%
V
IN
- V
OUT
Dropout Voltage
(Note 10)
I
L
= 300 mA
80
100
120
mV
I
L
= 3A
800
1000
1200
I
GND
Ground Pin Current In
Normal Operation
Mode
I
L
= 300 mA
5
9
10
mA
I
L
= 3A
6
14
15
I
GND
Ground Pin Current In
Shutdown Mode
V
SD
0.3V
1
10
A
-40C
T
J
85C
50
I
O(PK)
Peak Output Current
V
O
V
O(NOM)
- 4%
4.5
A
SHORT CIRCUIT PROTECTION
I
SC
Short Circuit Current
6
A
LP3873/LP3876
www.national.com
5
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