LP3853/LP3856
3A Fast Ultra Low Dropout Linear Regulators
General Description
The LP3853/LP3856 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 LP3853/LP3856
are developed on a CMOS process which allows low quies-
cent current operation independent of output load current.
This CMOS process also allows the LP3853/LP3856 to op-
erate under extremely low dropout conditions.
Dropout Voltage: Ultra low dropout voltage; typically 39mV
at 300mA load current and 390mV at 3A load current.
Ground Pin Current: Typically 4mA at 3A load current.
Shutdown Mode: Typically 10nA 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 0.06%
n
10nA 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
20030901
*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 applications
section for more information.
August 2003
LP3853/LP3856
3A
Fast
Ultra
Low
Dropout
Linear
Regulators
2003 National Semiconductor Corporation
DS200309
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 (Operating),
(Note 11)
2.5V to 7.0V
Shutdown Input Voltage
(Operating)
-0.3V to 7.0V
Maximum Operating Current (DC)
3A
Operating Junction Temp. Range
-40C to +125C
Electrical Characteristics
LP3853/LP3856
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)
+ 1V, I
L
= 10 mA, C
OUT
= 10F, V
SD
= 2V.
Symbol
Parameter
Conditions
Typ
(Note 4)
LP3853/6 (Note 5)
Units
Min
Max
V
O
Output Voltage
Tolerance
(Note 8)
V
OUT
+1V
<
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
+1V
<
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
39
45
60
mV
I
L
= 3A
390
450
600
I
GND
Ground Pin Current In
Normal Operation Mode
I
L
= 300 mA
4
9
10
mA
I
L
= 3A
4
9
10
I
GND
Ground Pin Current In
Shutdown Mode
V
SD
0.3V
0.01
10
50
A
I
O(PK)
Peak Output Current
(Note 2)
4.5
A
Short Circuit Protection
I
SC
Short Circuit Current
6
A
LP3853/LP3856
www.national.com
5
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