|
|
PDF LM2852 Data sheet ( Hoja de datos )
| Número de pieza | LM2852 | |
| Descripción | 2A 500/1500kHz Synchronous SIMPLE SWITCHER Buck Regulator | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LM2852 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
October 2006
LM2852
2A 500/1500kHz Synchronous SIMPLE SWITCHER® Buck
Regulator
General Description
The LM2852 SIMPLE SWITCHER® synchronous buck regu-
lator is a high frequency step-down switching voltage regu-
lator capable of driving up to a 2A load with excellent line and
load regulation. The LM2852 can accept an input voltage
between 2.85V and 5.5V and deliver an output voltage that is
factory programmable from 0.8V to 3.3V in 100mV incre-
ments. The LM2852 is available with a choice of two switch-
ing frequencies - 500kHz (LM2852Y) or 1.5MHz (LM2852X).
It also features internal, type-three compensation to deliver a
low component count solution. The exposed-pad TSSOP-14
package enhances the thermal performance of the LM2852.
Features
n Input voltage range of 2.85 to 5.5V
n Factory EEPROM set output voltages from 0.8V to 3.3V
in 100mV increments
n Maximum load current of 2A
n Voltage Mode Control
n Internal type-three compensation
n Switching frequency of 500kHz or 1.5MHz
n Low standby current of 10µA
n Internal 60 mΩ MOSFET switches
n Standard voltage options 0.8/1.0/1.2/1.5/1.8/2.5/3.3 volts
Applications
n Low voltage point of load regulation
n Local solution for FPGA/DSP/ASIC core power
n Broadband networking and communications
infrastructure
n Portable computing
Typical Application Circuit
20127001
SIMPLE SWITCHER®
SIMPLE SWITCHERreg; is a registered trademark of National Semiconductor Corporation
© 2006 National Semiconductor Corporation DS201270
20127002
www.national.com
1 page  
Electrical Characteristics AVIN = PVIN = 5V unless otherwise indicated under the Conditions column.
www.DLiamtaitSshienest4taUn.dcoamrd type are for TJ = 25˚C only; limits in boldface type apply over the junction temperature (TJ) range of -40˚C
to +125˚C. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values
represent the most likely parametric norm at TJ = 25˚C, and are provided for reference purposes only. (Continued)
Symbol
Parameter
Drange
Duty Cycle Range
ENABLE CONTROL4
VIH EN Pin Minimum
High Input
VIL EN Pin Maximum
Low Input
IEN EN Pin Pullup EN = 0V
Current
THERMAL CONTROLS
TSD TJ for Thermal
Shutdown
TSD-HYS
Hysteresis for
Thermal Shutdown
Conditions
Min Typ Max Units
0 100 %
75 % of
AVIN
25 % of
AVIN
1.2 µA
165 ˚C
10 ˚C
Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for which the device is
intended to be functional, but does not guarantee specfic performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Human body model: 1.5kΩ in series with 100pF. SW and PVIN pins are derated to 1.5kV
Note 3: VOUT measured in a non-switching, closed-loop configuration at the SNS pin.
Note 4: The enable pin is internally pulled up, so the LM2852 is automatically enabled unless an external enable voltage is applied.
5 www.national.com
5 Page 
Applications Information (Continued)
www.DataSheet4U.com
CHOOSING AN INDUCTANCE VALUE
The current ripple present in the output filter inductor is
determined by the input voltage, output voltage, switching
frequency and inductance according to the following equa-
tion:
The maximum inductor current for a 2A load would therefore
be 2A plus 60.8 mA, 2.0608A. As shown in the ripple equa-
tion, the current ripple is inversely proportional to induc-
tance.
where ∆IL is the peak-to-peak current ripple, D is the duty
cycle VOUT/VIN, VIN is the input voltage applied to the PVIN
pin, VOUT is the output voltage of the switcher, f is the
switching frequency and L is the inductance of the output
filter inductor. Knowing the current ripple is important for
inductor selection since the peak current through the induc-
tor is the load current plus one half the ripple current. Care
must be taken to ensure the peak inductor current does not
reach a level high enough to trip the current limit circuitry of
the LM2852.
As an example, consider a 5V to 1.2V conversion and a
500kHz switching frequency. According to Table 1, a 15µH
inductor may be used. Calculating the expected peak-to-
peak ripple,
OUTPUT FILTER INDUCTORS
Once the inductance value is chosen, the key parameter for
selecting the output filter inductor is its saturation current
(Isat) specification. Typically Isat is given by the manufacturer
as the current at which the inductance of the coil falls to a
certain percentage of the nominal inductance. The Isat of an
inductor used in an application should be greater than the
maximum expected inductor current to avoid saturation. Be-
low is a table of inductors that may be suitable in LM2852
applications.
TABLE 2. LM2852 Output Filter Inductors
Inductance (µH)
1
1
6.8
7
10
10
12
15
15
18
22
22
22
27
33
33
Part Number
DO1608C-102
DO1813P-102HC
DO3316P-682
MSS1038-702NBC
DO3316P-103
MSS1038-103NBC
MSS1038-123NBC
D03316P-153
MSS1038-153NBC
MSS1038-183NBC
DO3316P-223
MSS1038-223NBC
DO3340P-223
MSS1038-273NBC
MSS1038-333NBC
DO3340P-333
Vendor
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
Coilcraft
11 www.national.com
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet LM2852.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LM285 | MICROPOWER VOLTAGE REFERENCE DIODES |  ON Semiconductor |
| LM285 | MICROPOWER VOLTAGE REFERENCE DIODES |  Motorola Semiconductors |
| LM285-1.2 | Micropower Voltage Reference Diode | National Semiconductor |
| LM285-1.2 | LMx85-1.2 LM385B-1.2 Micropower Voltage References (Rev. J) |  Texas Instruments |
| 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 |