поискавой системы для электроныых деталей
  Russian  ▼
ALLDATASHEETRU.COM

X  

LM2678SD-3.3 датащи(PDF) 11 Page - Texas Instruments

номер детали LM2678SD-3.3
подробное описание детали  LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
Download  35 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
производитель  TI [Texas Instruments]
домашняя страница  http://www.ti.com
Logo TI - Texas Instruments

LM2678SD-3.3 датащи(HTML) 11 Page - Texas Instruments

Back Button LM2678SD-3.3 Datasheet HTML 7Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 8Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 9Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 10Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 11Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 12Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 13Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 14Page - Texas Instruments LM2678SD-3.3 Datasheet HTML 15Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 35 page
background image
LM2678
www.ti.com
SNVS029I – MARCH 2000 – REVISED APRIL 2013
INDUCTOR
The inductor is the key component in a switching regulator. For efficiency the inductor stores energy during the
switch ON time and then transfers energy to the load while the switch is OFF.
Nomographs are used to select the inductance value required for a given set of operating conditions. The
nomographs assume that the circuit is operating in continuous mode (the current flowing through the inductor
never falls to zero). The magnitude of inductance is selected to maintain a maximum ripple current of 30% of the
maximum load current. If the ripple current exceeds this 30% limit the next larger value is selected.
The inductors offered have been specifically manufactured to provide proper operation under all operating
conditions of input and output voltage and load current. Several part types are offered for a given amount of
inductance. Both surface mount and through-hole devices are available. The inductors from each of the three
manufacturers have unique characteristics.
Renco: ferrite stick core inductors; benefits are typically lowest cost and can withstand ripple and transient peak
currents above the rated value. These inductors have an external magnetic field, which may generate EMI.
Pulse Engineering: powdered iron toroid core inductors; these also can withstand higher than rated currents and,
being toroid inductors, will have low EMI.
Coilcraft: ferrite drum core inductors; these are the smallest physical size inductors and are available only as
surface mount components. These inductors also generate EMI but less than stick inductors.
OUTPUT CAPACITOR
The output capacitor acts to smooth the dc output voltage and also provides energy storage. Selection of an
output capacitor, with an associated equivalent series resistance (ESR), impacts both the amount of output ripple
voltage and stability of the control loop.
The output ripple voltage of the power supply is the product of the capacitor ESR and the inductor ripple current.
The capacitor types recommended in the tables were selected for having low ESR ratings.
In addition, both surface mount tantalum capacitors and through-hole aluminum electrolytic capacitors are offered
as solutions.
Impacting frequency stability of the overall control loop, the output capacitance, in conjunction with the inductor,
creates a double pole inside the feedback loop. In addition the capacitance and the ESR value create a zero.
These frequency response effects together with the internal frequency compensation circuitry of the LM2678
modify the gain and phase shift of the closed loop system.
As a general rule for stable switching regulator circuits it is desired to have the unity gain bandwidth of the circuit
to be limited to no more than one-sixth of the controller switching frequency. With the fixed 260KHz switching
frequency of the LM2678, the output capacitor is selected to provide a unity gain bandwidth of 40KHz maximum.
Each recommended capacitor value has been chosen to achieve this result.
In some cases multiple capacitors are required either to reduce the ESR of the output capacitor, to minimize
output ripple (a ripple voltage of 1% of Vout or less is the assumed performance condition), or to increase the
output capacitance to reduce the closed loop unity gain bandwidth (to less than 40KHz). When parallel
combinations of capacitors are required it has been assumed that each capacitor is the exact same part type.
The RMS current and working voltage (WV) ratings of the output capacitor are also important considerations. In a
typical step-down switching regulator, the inductor ripple current (set to be no more than 30% of the maximum
load current by the inductor selection) is the current that flows through the output capacitor. The capacitor RMS
current rating must be greater than this ripple current. The voltage rating of the output capacitor should be
greater than 1.3 times the maximum output voltage of the power supply. If operation of the system at elevated
temperatures is required, the capacitor voltage rating may be de-rated to less than the nominal room temperature
rating. Careful inspection of the manufacturer's specification for de-rating of working voltage with temperature is
important.
Copyright © 2000–2013, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM2678


Аналогичный номер детали - LM2678SD-3.3

производительномер деталидатащиподробное описание детали
logo
National Semiconductor ...
LM2678SD-3.3 NSC-LM2678SD-3.3 Datasheet
459Kb / 27P
   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678SD-3.3 NSC-LM2678SD-3.3 Datasheet
836Kb / 27P
   SIMPLE SWITCHER짰 High Efficiency 5A Step-Down Voltage Regulator
logo
Texas Instruments
LM2678SD-3.3 TI-LM2678SD-3.3 Datasheet
1Mb / 35P
[Old version datasheet]   LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678SD-3.3 TI-LM2678SD-3.3 Datasheet
1Mb / 35P
[Old version datasheet]   LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678SD-3.3/NOPB TI1-LM2678SD-3.3/NOPB Datasheet
2Mb / 36P
[Old version datasheet]   LM2678 SIMPLE SWITCHER짰 High Efficiency 5-A Step-Down Voltage Regulator
More results

Аналогичное описание - LM2678SD-3.3

производительномер деталидатащиподробное описание детали
logo
Texas Instruments
LM2678S-ADJ TI-LM2678S-ADJ Datasheet
1Mb / 35P
[Old version datasheet]   LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678SD-5.0 TI-LM2678SD-5.0 Datasheet
1Mb / 35P
[Old version datasheet]   LM2678 SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678 TI-LM2678_15 Datasheet
1Mb / 34P
[Old version datasheet]   LM2678 SIMPLE SWITCHER짰 High Efficiency 5A Step-Down Voltage Regulator
logo
National Semiconductor ...
LM2678 NSC-LM2678 Datasheet
459Kb / 27P
   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2678S-12 NSC-LM2678S-12 Datasheet
356Kb / 23P
   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator
LM2677 NSC-LM2677 Datasheet
847Kb / 26P
   SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator with Sync
logo
Texas Instruments
LM2678 TI1-LM2678 Datasheet
2Mb / 36P
[Old version datasheet]   LM2678 SIMPLE SWITCHER짰 High Efficiency 5-A Step-Down Voltage Regulator
logo
National Semiconductor ...
LM2676 NSC-LM2676 Datasheet
350Kb / 25P
   SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator
LM2678 NSC-LM2678_05 Datasheet
836Kb / 27P
   SIMPLE SWITCHER짰 High Efficiency 5A Step-Down Voltage Regulator
logo
Texas Instruments
LM2676S-5 TI1-LM2676S-5 Datasheet
1Mb / 35P
[Old version datasheet]   LM2676 SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35


датащи скачать

Go To PDF Page


ссылки URL




Конфиденциальность
ALLDATASHEETRU.COM
Вашему бизинису помогли Аллдатащит?  [ DONATE ] 

Что такое Аллдатащит   |   реклама   |   контакт   |   Конфиденциальность   |   обмен ссыками   |   поиск по производителю
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com