Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

LM2734Z Datasheet(PDF) 11 Page - Texas Instruments

Part # LM2734Z
Description  LM2734Z/LM2734ZQ Thin SOT 1A Load Step-Down DC-DC Regulator
Download  32 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  TI [Texas Instruments]
Direct Link  http://www.ti.com
Logo TI - Texas Instruments

LM2734Z Datasheet(HTML) 11 Page - Texas Instruments

Back Button LM2734Z_15 Datasheet HTML 7Page - Texas Instruments LM2734Z_15 Datasheet HTML 8Page - Texas Instruments LM2734Z_15 Datasheet HTML 9Page - Texas Instruments LM2734Z_15 Datasheet HTML 10Page - Texas Instruments LM2734Z_15 Datasheet HTML 11Page - Texas Instruments LM2734Z_15 Datasheet HTML 12Page - Texas Instruments LM2734Z_15 Datasheet HTML 13Page - Texas Instruments LM2734Z_15 Datasheet HTML 14Page - Texas Instruments LM2734Z_15 Datasheet HTML 15Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 32 page
background image
IRMS-OUT = IO x
r
12
'VO = 'iL x (RESR +
1
8 x fS x CO
)
IRMS-IN = IO x
D x
r
2
12
1-D +
LM2734Z
www.ti.com
SNVS334E – JANUARY 2005 – REVISED APRIL 2013
where fs is the switching frequency and IO is the output current. When selecting an inductor, make sure that it is
capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden
reduction in inductance and prevent the regulator from operating correctly. Because of the speed of the internal
current limit, the peak current of the inductor need only be specified for the required maximum output current. For
example, if the designed maximum output current is 0.5A and the peak current is 0.7A, then the inductor should
be specified with a saturation current limit of >0.7A. There is no need to specify the saturation or peak current of
the inductor at the 1.7A typical switch current limit. The difference in inductor size is a factor of 5. Because of the
operating frequency of the LM2734Z, ferrite based inductors are preferred to minimize core losses. This presents
little restriction since the variety of ferrite based inductors is huge. Lastly, inductors with lower series resistance
(DCR) will provide better operating efficiency. For recommended inductors see Example Circuits.
INPUT CAPACITOR
An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The
primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent
Series Inductance). The recommended input capacitance is 10µF, although 4.7µF works well for input voltages
below 6V. The input voltage rating is specifically stated by the capacitor manufacturer. Make sure to check any
recommended deratings and also verify if there is any significant change in capacitance at the operating input
voltage and the operating temperature. The input capacitor maximum RMS input current rating (IRMS-IN) must be
greater than:
(20)
It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always
calculate the RMS at the point where the duty cycle, D, is closest to 0.5. The ESL of an input capacitor is usually
determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL
and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2734Z, certain
capacitors may have an ESL so large that the resulting impedance (2
πfL) will be higher than that required to
provide stable operation. As a result, surface mount capacitors are strongly recommended. Sanyo POSCAP,
Tantalum or Niobium, Panasonic SP or Cornell Dubilier ESR, and multilayer ceramic capacitors (MLCC) are all
good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use
X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to see how rated capacitance varies over
operating conditions.
OUTPUT CAPACITOR
The output capacitor is selected based upon the desired output ripple and transient response. The initial current
of a load transient is provided mainly by the output capacitor. The output ripple of the converter is:
(21)
When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the
output ripple will be approximately sinusoidal and 90° phase shifted from the switching action. Given the
availability and quality of MLCCs and the expected output voltage of designs using the LM2734Z, there is really
no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to
bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic
capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not.
Since the output capacitor is one of the two external components that control the stability of the regulator control
loop, most applications will require a minimum at 10 µF of output capacitance. Capacitance can be increased
significantly with little detriment to the regulator stability. Like the input capacitor, recommended multilayer
ceramic capacitors are X7R or X5R. Again, verify actual capacitance at the desired operating voltage and
temperature.
Check the RMS current rating of the capacitor. The RMS current rating of the capacitor chosen must also meet
the following condition:
(22)
Copyright © 2005–2013, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM2734Z


Similar Part No. - LM2734Z_15

ManufacturerPart #DatasheetDescription
logo
Texas Instruments
LM2734Z TI1-LM2734Z_14 Datasheet
1Mb / 29P
[Old version datasheet]   Thin SOT23 1A Load Step-Down DC-DC Regulator
LM2734Z TI1-LM2734Z_16 Datasheet
1Mb / 36P
[Old version datasheet]   Thin SOT 1-A Load Step-Down DC-DC Regulator
More results

Similar Description - LM2734Z_15

ManufacturerPart #DatasheetDescription
logo
Texas Instruments
LM2734 TI1-LM2734 Datasheet
1Mb / 31P
[Old version datasheet]   LM2734 Thin SOT 1A Load Step-Down DC-DC Regulator
logo
National Semiconductor ...
LM2734 NSC-LM2734 Datasheet
459Kb / 22P
   Thin SOT23 1A Load Step-Down DC-DC Regulator
LM2734Z NSC-LM2734Z Datasheet
775Kb / 9P
   Thin SOT23 1A Load Step-Down DC-DC Regulator
logo
Texas Instruments
LM2734Z TI1-LM2734Z_14 Datasheet
1Mb / 29P
[Old version datasheet]   Thin SOT23 1A Load Step-Down DC-DC Regulator
LM2734Z TI1-LM2734Z_16 Datasheet
1Mb / 36P
[Old version datasheet]   Thin SOT 1-A Load Step-Down DC-DC Regulator
LM2736YMKX TI-LM2736YMKX Datasheet
1Mb / 31P
[Old version datasheet]   LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator
LM2736XMK TI-LM2736XMK Datasheet
1Mb / 31P
[Old version datasheet]   LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator
LM2736YMK TI-LM2736YMK Datasheet
1Mb / 31P
[Old version datasheet]   LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator
LM2736XMK TI1-LM2736XMK Datasheet
1Mb / 31P
[Old version datasheet]   LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator
LM2736 TI-LM2736_15 Datasheet
1Mb / 36P
[Old version datasheet]   LM2736 Thin SOT 750 mA Load Step-Down DC-DC 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


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
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