|
|
PDF LP3872ESX-2.5 Data sheet ( Hoja de datos )
| Número de pieza | LP3872ESX-2.5 | |
| Descripción | 1.5A Fast Ultra Low Dropout Linear Regulators | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LP3872ESX-2.5 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
|
No Preview Available !
August 2003
LP3872/LP3875
1.5A Fast Ultra Low Dropout Linear Regulators
General Description
The LP3872/LP3875 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 LP3872/LP3875
are developed on a CMOS process which allows low quies-
cent current operation independent of output load current.
This CMOS process also allows the LP3872/LP3875 to op-
erate under extremely low dropout conditions.
Dropout Voltage: Ultra low dropout voltage; typically 38mV
at 150mA load current and 380mV at 1.5A load current.
Ground Pin Current: Typically 6mA at 1.5A 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 1.5A 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 −40˚C to +125˚C 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
20063301
*SD and ERROR pins must be pulled high through a 10kΩ pull-up resistor. Connect the ERROR pin to ground if this function is not used. See applications
section for more information.
© 2003 National Semiconductor Corporation DS200633
www.national.com
1 page  
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
Lead Temperature
(Soldering, 5 sec.)
ESD Rating (Note 3)
Power Dissipation (Note 2)
Input Supply Voltage (Survival)
Shutdown Input Voltage
(Survival)
Output Voltage (Survival), (Note
6), (Note 7)
−65˚C to +150˚C
260˚C
2 kV
Internally Limited
−0.3V to +7.5V
−0.3V to +7.5V
−0.3V to +6.0V
IOUT (Survival)
Short Circuit Protected
Maximum Voltage for ERROR
Pin VIN
Maximum Voltage for SENSE Pin
VOUT
Operating Ratings
Input Supply Voltage (Operating),
(Note 11)
Shutdown Input Voltage
(Operating)
Maximum Operating Current (DC)
Operating Junction Temp. Range
2.5V to 7.0V
−0.3V to 7.0V
1.5A
−40˚C to +125˚C
Electrical Characteristics
LP3872/LP3875
Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range.
Unless otherwise specified: VIN = VO(NOM) + 1V, IL = 10 mA, COUT = 10µF, VSD = 2V.
Symbol
Parameter
Conditions
Typ
LP3872/5 (Note 5)
Units
VO
∆V OL
∆VO/ ∆IOUT
Output Voltage
Tolerance
(Note 8)
Output Voltage Line
Regulation (Note 8)
Output Voltage Load
Regulation
VOUT +1V < VIN< 7.0V
10 mA < IL < 1.5A
VOUT +1V < VIN < 7.0V
10 mA < IL < 1.5A
(Note 4)
0
0.02
0.06
0.06
0.12
Min
-1.5
-3.0
Max
+1.5
+3.0
%
%
%
(Note 8)
VIN - VOUT
Dropout Voltage
(Note 10)
IL = 150 mA
IL = 1.5A
38
380
45
55
mV
450
550
IGND
Ground Pin Current In
Normal Operation Mode
IL = 150 mA
IL = 1.5A
5
6
9
10
mA
14
15
IGND
Ground Pin Current In
Shutdown Mode
VSD ≤ 0.3V
0.01
10 µA
50
IO(PK)
Peak Output Current
Short Circuit Protection
(Note 2)
1.8
A
ISC Short Circuit Current
3.2 A
5 www.national.com
5 Page 
Application Hints (Continued)
DROPOUT VOLTAGE
The dropout voltage of a regulator is defined as the minimum
input-to-output differential required to stay within 2% of the
nominal output voltage. For CMOS LDOs, the dropout volt-
age is the product of the load current and the Rds(on) of the
internal MOSFET.
REVERSE CURRENT PATH
The internal MOSFET in LP3872 and LP3875 has an inher-
ent parasitic diode. During normal operation, the input volt-
age is higher than the output voltage and the parasitic diode
is reverse biased. However, if the output is pulled above the
input in an application, then current flows from the output to
the input as the parasitic diode gets forward biased. The
output can be pulled above the input as long as the current
in the parasitic diode is limited to 200mA continuous and 1A
peak.
POWER DISSIPATION/HEATSINKING
LP3872 and LP3875 can deliver a continuous current of 3A
over the full operating temperature range. A heatsink may be
required depending on the maximum power dissipation and
maximum ambient temperature of the application. Under all
possible conditions, the junction temperature must be within
the range specified under operating conditions. The total
power dissipation of the device is given by:
PD = (VIN−VOUT)IOUT+ (VIN)IGND
where IGND is the operating ground current of the device
(specified under Electrical Characteristics).
The maximum allowable temperature rise (TRmax) depends
on the maximum ambient temperature (TAmax) of the appli-
cation, and the maximum allowable junction temperature
(TJmax):
TRmax = TJmax− TAmax
The maximum allowable value for junction to ambient Ther-
mal Resistance, θJA, can be calculated using the formula:
θJA = TRmax / PD
LP3872 and LP3875 are available in TO-220 and TO-263
packages. The thermal resistance depends on amount of
copper area or heat sink, and on air flow. If the maximum
allowable value of θJA calculated above is ≥ 60 ˚C/W for
TO-220 package and ≥ 60 ˚C/W for TO-263 package no
heatsink is needed since the package can dissipate enough
heat to satisfy these requirements. If the value for allowable
θJA falls below these limits, a heat sink is required.
HEATSINKING TO-220 PACKAGE
The thermal resistance of a TO220 package can be reduced
by attaching it to a heat sink or a copper plane on a PC
board. If a copper plane is to be used, the values of θJA will
be same as shown in next section for TO263 package.
The heatsink to be used in the application should have a
heatsink to ambient thermal resistance,
θHA≤ θJA − θCH − θJC.
In this equation, θCH is the thermal resistance from the case
to the surface of the heat sink and θJC is the thermal resis-
tance from the junction to the surface of the case. θJC is
about 3˚C/W for a TO220 package. The value for θCH de-
pends on method of attachment, insulator, etc. θCH varies
between 1.5˚C/W to 2.5˚C/W. If the exact value is unknown,
2˚C/W can be assumed.
HEATSINKING TO-263 PACKAGE
The TO-263 package uses the copper plane on the PCB as
a heatsink. The tab of these packages are soldered to the
copper plane for heat sinking. Figure 3 shows a curve for the
θJA of TO-263 package for different copper area sizes, using
a typical PCB with 1 ounce copper and no solder mask over
the copper area for heat sinking.
20063332
FIGURE 3. θJA vs Copper (1 Ounce) Area for TO-263
package
As shown in the figure, increasing the copper area beyond 1
square inch produces very little improvement. The minimum
value for θJA for the TO-263 package mounted to a PCB is
32˚C/W.
Figure 4 shows the maximum allowable power dissipation
for TO-263 packages for different ambient temperatures,
assuming θJA is 35˚C/W and the maximum junction tempera-
ture is 125˚C.
20063333
FIGURE 4. Maximum power dissipation vs ambient
temperature for TO-263 package
11 www.national.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet LP3872ESX-2.5.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LP3872ESX-2.5 | 1.5A Fast Ultra Low Dropout Linear Regulators | National Semiconductor |
| LP3872ESX-2.5 | 1.5A Fast Ultra Low Dropout Linear Regulators | National Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |