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LP3883
3A Fast-Response Ultra Low Dropout Linear Regulators
General Description
The LP3883 is a high-current, fast-response regulator which
can maintain output voltage regulation with minimum input to
output voltage drop. Fabricated on a CMOS process, the
device operates from two input voltages: Vbias provides
voltage to drive the gate of the N-MOS power transistor,
while Vin is the input voltage which supplies power to the
load. The use of an external bias rail allows the part to
operate from ultra low Vin voltages. Unlike bipolar regula-
tors, the CMOS architecture consumes extremely low quies-
cent current at any output load current. The use of an
N-MOS power transistor results in wide bandwidth, yet mini-
mum external capacitance is required to maintain loop sta-
bility.
The fast transient response of these devices makes them
suitable for use in powering DSP, Microcontroller Core volt-
ages and Switch Mode Power Supply post regulators. The
parts are available in TO-220 and TO-263 packages.
Dropout Voltage: 210 mV (typ)
@
3A load current.
Ground Pin Current: 3 mA (typ) at full load.
Shutdown Current: 60 nA (typ) when S/D pin is low.
Precision Output Voltage: 1.5% room temperature accu-
racy.
Features
n
Ultra low dropout voltage (210 mV
@
3A typ)
n
Low ground pin current
n
Load regulation of 0.04%/A
n
60 nA typical quiescent current in shutdown
n
1.5% output accuracy (25C)
n
TO-220, TO-263 packages
n
Over temperature/over current protection
n
-40C to +125C junction temperature range
Applications
n
DSP Power Supplies
n
Server Core and I/O Supplies
n
Linear Power Supplies for PC Add-in-Cards
n
Set-Top Box Power Supplies
n
Microprocessor Power Supplies
n
High Efficiency Linear Power Supplies
n
SMPS Post-Regulators
Typical Application Circuit
20062401
At least 4.7 F of input and output capacitance is required for stability.
Connection Diagrams
20062402
TO-220, Top View
20062403
TO-263, Top View
August 2003
LP3883
3A
Fast-Response
Ultra
Low
Dropout
Linear
Regulators
2003 National Semiconductor Corporation
DS200624
www.national.com
Ordering Information
Order Number
Package Type
Package Drawing
Supplied As
LP3883ES-1.2
TO263-5
TS5B
Rail
LP3883ESX-1.2
TO263-5
TS5B
Tape and Reel
LP3883ET-1.2
TO220-5
T05D
Rail
LP3883ES-1.5
TO263-5
TS5B
Rail
LP3883ESX-1.5
TO263-5
TS5B
Tape and Reel
LP3883ET-1.5
TO220-5
T05D
Rail
LP3883ES-1.8
TO263-5
TS5B
Rail
LP3883ESX-1.8
TO263-5
TS5B
Tape and Reel
LP3883ET-1.8
TO220-5
T05D
Rail
Block Diagram
20062424
LP3883
www.national.com
2
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 Temp. (Soldering, 5 seconds)
260C
ESD Rating
Human Body Model (Note 3)
Machine Model (Note 10)
2 kV
200V
Power Dissipation (Note 2)
Internally Limited
V
IN
Supply Voltage (Survival)
-0.3V to +6V
V
BIAS
Supply Voltage (Survival)
-0.3V to +7V
Shutdown Input Voltage (Survival)
-0.3V to +7V
I
OUT
(Survival)
Internally Limited
Output Voltage (Survival)
-0.3V to +6V
Junction Temperature
-40C to +150C
Operating Ratings
V
IN
Supply Voltage
(V
OUT
+ V
DO
) to 5.5V
Shutdown Input Voltage
0 to +6V
I
OUT
3A
Operating Junction
Temperature Range
-40C to +125C
V
BIAS
Supply Voltage
4.5V to 6V
Electrical Characteristics
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, V
BIAS
= 4.5V, I
L
= 10 mA, C
IN
=
C
OUT
= 4.7 F, V
S/D
= V
BIAS
.
Symbol
Parameter
Conditions
Typical
(Note 4)
MIN
(Note 5)
MAX
(Note 5)
Units
V
O
Output Voltage Tolerance
10 mA
<
I
L
<
3A
V
O
(NOM) + 1V
V
IN
5.5V
4.5V
V
BIAS
6V
1.216
1.198
1.186
1.234
1.246
V
1.5
1.478
1.455
1.522
1.545
1.8
1.773
1.746
1.827
1.854
V
O
/
V
IN
Output Voltage Line Regulation
(Note 7)
V
O
(NOM) + 1V
V
IN
5.5V
0.01
%/V
V
O
/
I
L
Output Voltage Load Regulation
(Note 8)
10 mA
<
I
L
<
3A
0.04
0.06
%/A
V
DO
Dropout Voltage (Note 9)
I
L
= 3A
210
270
420
mV
I
Q
(V
IN
)
Quiescent Current Drawn from
V
IN
Supply
10 mA
<
I
L
<
3A
3
7
8
mA
V
S/D
0.3V
0.03
1
30
A
I
Q
(V
BIAS
)
Quiescent Current Drawn from
V
BIAS
Supply
10 mA
<
I
L
<
3A
1
2
3
mA
V
S/D
0.3V
0.03
1
30
A
I
SC
Short-Circuit Current
V
OUT
= 0V
6
A
Shutdown Input
V
SDT
Output Turn-off Threshold
Output = ON
0.7
1.3
V
Output = OFF
0.7
0.3
Td (OFF)
Turn-OFF Delay
R
LOAD
X C
OUT
<<
Td (OFF)
20
s
Td (ON)
Turn-ON Delay
R
LOAD
X C
OUT
<<
Td (ON)
15
I
S/D
S/D Input Current
V
S/D
=1.3V
1
A
V
S/D
0.3V
-1
LP3883
www.national.com
3
Electrical Characteristics
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, V
BIAS
= 4.5V, I
L
= 10 mA, C
IN
=
C
OUT
= 4.7 F, V
S/D
= V
BIAS
. (Continued)
Symbol
Parameter
Conditions
Typical
(Note 4)
MIN
(Note 5)
MAX
(Note 5)
Units
AC Parameters
PSRR (V
IN
)
Ripple Rejection for V
IN
Input
Voltage
V
IN
= V
OUT
+1V, f = 120 Hz
80
dB
V
IN
= V
OUT
+ 1V, f = 1 kHz
65
PSRR
(V
BIAS
)
Ripple Rejection for V
BIAS
Voltage
V
BIAS
= V
OUT
+ 3V, f = 120 Hz
70
V
BIAS
= V
OUT
+ 3V, f = 1 kHz
65
Output Noise Density
f = 120 Hz
1
V/root-Hz
e
n
Output Noise Voltage
V
OUT
= 1.8V
BW = 10 Hz - 100 kHz
150
V (rms)
BW = 300 Hz - 300 kHz
90
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Operating ratings indicate conditions for which the device
is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications, see Electrical Characteristics. Specifications do not
apply when operating the device outside of its rated operating conditions.
Note 2: At elevated temperatures, device power dissipation must be derated based on package thermal resistance and heatsink thermal values.
J-A
for TO-220
devices is 65C/W if no heatsink is used. If the TO-220 device is attached to a heatsink, a
J-S
value of 4C/W can be assumed.
J-A
for TO-263 devices is
approximately 40C/W if soldered down to a copper plane which is at least 1.5 square inches in area. If power dissipation causes the junction temperature to exceed
specified limits, the device will go into thermal shutdown.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin.
Note 4: Typical numbers represent the most likely parametric norm for 25C operation.
Note 5: Limits are guaranteed through testing, statistical correlation, or design.
Note 6: If used in a dual-supply system where the regulator load is returned to a negative supply, the output pin must be diode clamped to ground.
Note 7: Output voltage line regulation is defined as the change in output voltage from nominal value resulting from a change in input voltage.
Note 8: Output voltage load regulation is defined as the change in output voltage from nominal value as the load current increases from no load to full load.
Note 9: Dropout voltage is defined as the minimum input to output differential required to maintain the output with 2% of nominal value.
Note 10: The machine model is a 220 pF capacitor discharged directly into each pin. The machine model ESD rating of pin 5 is 100V.
LP3883
www.national.com
4
Typical Performance Characteristics
Unless otherwise specified: T
A
= 25C, C
OUT
= 4.7F, Cin
= 4.7F, S/D pin is tied to V
BIAS
, V
IN
= 2.2V, V
OUT
= 1.8V.
Dropout vs I
L
I
GND
vs VSD
20062404
20062405
V
OUT
vs Temperature
DC Load Regulation
20062406
20062407
Line Regulation vs V
IN
Line Regulation vs V
BIAS
20062408
20062409
LP3883
www.national.com
5
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