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Datasheet: L1581 (No company)

Dual Input Ultra Low Dropout Voltage Regulator (ULDO)

 

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1
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
GENERAL DESCRIPTION
The L1581 is a positive and very low
dropout voltage regulator with 5A output
current capability. When supplying 2.5V or
2.8V on Motherboards or VGA Card where
both 5V and 3.3V supplies are available,
the superior dropout characteristics of the
L1581 result in reduced heat dissipation
compared to regular LDOs, thus allowing
heat sink reduction. The adjustable version
requires only two external resistors to set
the output. The L1581 features a low
dropout of less than 600mV and offers fast
transient response, remote sense, internal
limiting, thermal shutdown and safe
operating area protection of the output
device.
The L1581 is a five terminal adjustable
voltage regulator available in the popular 5
pin TO-252 packages.
FEATURES
Low dropout voltage 600mV at rated load
current
Remote sense operation
Fast transient response
0.5% voltage reference initial accuracy
Standard 5 terminal, Low cost TO-252
packages
APPLICATIONS
3.3V to 2.8V or 2.5V for Motherboards or
VGA Card
Spilt plane microprocessor supplies
Post regulator for switching supplies
TYPICAL APPLICATION
Adjustable Output Parts
(2)
Vin
C3
0.033uF
Vout
Iadj
Vo = Vref (1+R2/R1) + Iadj x R2
330uF
C4
L1581X
3
5
4
2
1
OUT
Vin
CTR'L
ADJ SENSE
R2
C2
10uF
R1
C1
330uF
Vctrl
Vref




2
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
Fixed Output Parts
330uF
C4
Vctrl
L1581X-2.5
3
5
4
2
1
OUT
Vin
CTR'L
ADJ SENSE
2.5V Vout
C1
330uF
C2
10uF
Vin


330uF
C4
Vctrl
L1581X-3.3
3
5
4
2
1
OUT
Vin
CTR'L
ADJ SENSE
C2
10uF
C1
330uF
Vin
3.3V Vout
NOTES :
(1) If the same voltage is input to both INPUT and CONTROL, then the dropout voltage will become 1.3V
maximum.
(2) A small (~0.033uF) capacitor can be used to bypass the ADJUST pin to improve transient response, if needed.
(3)
Capacitor values are for reference only. Good quality, low ESR tantalum or aluminum electrolytic capacitors
should be used. Increasing the value of the output capacitor will improve the overall transient response.



3
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage, V
IN
Control Input Voltage, V
CTRL
7V
13.2V
Operating Junction
Temperature Range, T
J
0 to 125 C
Power Dissipation, P
D
Internally
Limited
Storage Temperature
Range, T
STG
-40 to 150 C
Thermal Resistance
Junction to Case,
JC
3 C/W
Lead Temperature, T
LEAD
(Soldering, 10 Seconds)
260 C
Thermal Resistance
Junction to Ambient,
JA
60 C/W
ELECTRICAL CHARACTERISTICS (
Unless otherwise specified, V
out
= V
sns
, V
adj
= 0V ,
C
ctl
= C
in
= C
out
=10
uF
,T
J
= 25 C)
Parameter
Symbol
Test Conditions
Typical
Limits
V
CTRL
=4.5V, V
IN
=2.05V, I
OUT
=10mA
1.237V~1.263V
Reference Voltage
(1)
(Adj. Voltage
Versions)
V
REF
V
CTRL
= 4.5V, 10mA <
I
OUT
< 5A,
V
IN
= 2.05V
1.25V
1.231V~1.269V
Dropout Voltage
(1) (2)
Minimum V
IN
V
I
- V
O
V
CTRL
= 4.75V, I
OUT
= 5A
0.54V 0.62V
(Max)
V
CTRL
= 5V, V
IN
= V
OUT
0.8V,
I
OUT
=10mA
1%
Output Voltage
(1)
(Fixed Voltage
Versions)
V
OUT
V
CTRL
= 5V, 10mA <
I
OUT
< 5A,
V
IN
= V
OUT
0.8V
V
OUT
1.5%
Line Regulation
(1)
REG
(LINE)
V
CTRL
= 4.5V to 12V, V
IN
= (V
OUT
0.8V) to 5.5V, I
OUT
= 10mA
1.0mV 3.0mV
Load Regulation
REG
(LOAD)
V
CTRL
= 4.5V, V
IN
= (V
OUT
0.8V) ,
I
OUT
= 10mA ~ 5A
1.0mV 5.0mV
Thermal Regulation
(6)
REG
(Thermal)
0.002
% / W
0.02% / W
Minimum Load
Current
(4)
I
O
V
CTRL
= 5V, V
IN
= V
OUT
0.8V
5mA 10mA
Adjust Pin Current
I
ADJ
V
CTRL
= 4.5V, V
IN
=
V
OUT
0.8V
,
I
OUT
= 10mA
50
A 120A
Control Pin Current
(3)
I
CTRL
V
CTRL
= 4.5V, V
IN
=
V
OUT
0.8V
,
I
OUT
= 5A
33mA 120mA
Current Limit
I
CL
V
CTRL
= 4.5V, V
IN
=
V
OUT
0.8V
V
OUT
= 100mV
5.1A
(Min)



4
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
Ripple Rejection
Ratio
(5)
R
A
V
CTRL
= V
IN
= 5V, I
OUT
= 5A
80dB 60dB
(Min)

NOTE :
(1) Low duty cycle pulse testing with Kelvin connections required.
(2) Minimum input to output voltage differential required to maintain 1% regulation.
(3) Current used to drive the output section.
(4) Required to maintain regulation. Resistor divider R1, R2 is usually utilized for minimum load current.
(5) V
RIPPLE
= 1V
PK-PK
, 120Hz.
(6)
30ms.
DEVICE SELECTION GUIDE
Device
L1581D L1581D-2.5
L1581D-3.3
Package
TO-252 TO-252 TO-252
Marking
L1581D L1581D-2.5
L1581D-3.3

PIN CONFIGURATIONS
2
1
5
4
3
Pin #
Function
1 Sense
2 Adjust
3 Output
4 Control
5 Input
Note: TAB is Output Pin



5
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
PIN FUNCTIONS
NO FUNCTION
DESCRIPTION
1 Sense
This pin is the positive side of the reference voltage for the device. With
this pin it is possible to Kelvin sense the output voltage at the load.
2
Adjust
This pin is the negative side of the reference voltage for the device.
Transient response can be improved by adding a small bypass capacitor
from the adjust pin to ground.
3 Output
This is the power output of the device, and is electrically connected to
the TAB.
4 Control
This pin is the supply pin for the control circuitry for the device. The
current flow into this pin will be approximately 1% of the output. For the
device to regulate, the voltage at this pin must be between 1.0V and
1.3V greater than the output voltage (see dropout specifications).
5 Input
This is the collector input to the power device of the L1581. The output
load current is supplied through this pin. For the device to regulate, the
voltage on this pin must be between 0.1V and 0.7V greater than the
output, depending upon load current (see dropout specifications).





















6
Dual Input Ultra Low Dropout
Voltage Regulator (ULDO)
L1581 Series
TO-252
OCT-11-Y02
NIKO-SEM
TO-252 (DPAK) MECHANICAL DATA
mm
mm
Dimension
Min. Typ. Max.
Dimension
Min. Typ. Max.
A 9.7 H
0.89 2.03
B 2.19 2.38 I 6.35 6.73
C 0.46 0.58 J 5.21 5.46
D 0.89 1.27 K
E 0.46 0.53 L 0.64 0.89
F 0.00 0.13 M
1.27BSC
G 3.04
5.33 N
5
4
3
2
1
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