Moteur de recherche de fiches techniques de composants électroniques
  French  ▼
ALLDATASHEET.FR

X  

LM25576 Fiches technique(PDF) 11 Page - Texas Instruments

No de pièce LM25576
Description  LM25576/LM25576-Q1 SIMPLE SWITCHER짰 42V, 3A Step-Down Switching Regulator
Download  29 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  TI [Texas Instruments]
Site Internet  http://www.ti.com
Logo TI - Texas Instruments

LM25576 Fiches technique(HTML) 11 Page - Texas Instruments

Back Button LM25576_15 Datasheet HTML 7Page - Texas Instruments LM25576_15 Datasheet HTML 8Page - Texas Instruments LM25576_15 Datasheet HTML 9Page - Texas Instruments LM25576_15 Datasheet HTML 10Page - Texas Instruments LM25576_15 Datasheet HTML 11Page - Texas Instruments LM25576_15 Datasheet HTML 12Page - Texas Instruments LM25576_15 Datasheet HTML 13Page - Texas Instruments LM25576_15 Datasheet HTML 14Page - Texas Instruments LM25576_15 Datasheet HTML 15Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 29 page
background image
Sample and
Hold DC Level
0.5V/A
RAMP
TON
tON
CRAMP
(5P x (VIN ± VOUT) + 25P) x
LM25576, LM25576-Q1
www.ti.com
SNVS470G – JANUARY 2007 – REVISED APRIL 2013
Error Amplifier and PWM Comparator
The internal high gain error amplifier generates an error signal proportional to the difference between the
regulated output voltage and an internal precision reference (1.225V). The output of the error amplifier is
connected to the COMP pin allowing the user to provide loop compensation components, generally a type II
network, as illustrated in Figure 9. This network creates a pole at DC, a zero and a noise reducing high
frequency pole. The PWM comparator compares the emulated current sense signal from the RAMP generator to
the error amplifier output voltage at the COMP pin.
RAMP Generator
The ramp signal used in the pulse width modulator for current mode control is typically derived directly from the
buck switch current. This switch current corresponds to the positive slope portion of the output inductor current.
Using this signal for the PWM ramp simplifies the control loop transfer function to a single pole response and
provides inherent input voltage feed-forward compensation. The disadvantage of using the buck switch current
signal for PWM control is the large leading edge spike due to circuit parasitics that must be filtered or blanked.
Also, the current measurement may introduce significant propagation delays. The filtering, blanking time and
propagation delay limit the minimum achievable pulsewidth. In applications where the input voltage may be
relatively large in comparison to the output voltage, controlling small pulsewidths and duty cycles is necessary for
regulation. The LM25576 utilizes a unique ramp generator, which does not actually measure the buck switch
current but rather reconstructs the signal. Reconstructing or emulating the inductor current provides a ramp
signal to the PWM comparator that is free of leading edge spikes and measurement or filtering delays. The
current reconstruction is comprised of two elements; a sample & hold DC level and an emulated current ramp.
Figure 14. Composition of Current Sense Signal
The sample & hold DC level illustrated in Figure 14 is derived from a measurement of the re-circulating Schottky
diode anode current. The re-circulating diode anode should be connected to the IS pin. The diode current flows
through an internal current sense resistor between the IS and PGND pins. The voltage level across the sense
resistor is sampled and held just prior to the onset of the next conduction interval of the buck switch. The diode
current sensing and sample & hold provide the DC level of the reconstructed current signal. The positive slope
inductor current ramp is emulated by an external capacitor connected from the RAMP pin to AGND and an
internal voltage controlled current source. The ramp current source that emulates the inductor current is a
function of the Vin and Vout voltages per the following equation:
IRAMP = (5µ x (Vin – Vout)) + 25µA
(2)
Copyright © 2007–2013, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM25576 LM25576-Q1


Numéro de pièce similaire - LM25576_15

FabricantNo de pièceFiches techniqueDescription
logo
Texas Instruments
LM25576 TI1-LM25576_17 Datasheet
1Mb / 29P
[Old version datasheet]   SIMPLE SWITCHER 42V, 3A Step-Down Switching Regulator
More results

Description similaire - LM25576_15

FabricantNo de pièceFiches techniqueDescription
logo
Texas Instruments
LM25576MHX TI1-LM25576MHX Datasheet
1Mb / 29P
[Old version datasheet]   LM25576/LM25576-Q1 SIMPLE SWITCHER 42V, 3A Step-Down Switching Regulator
logo
National Semiconductor ...
LM25576_0703 NSC-LM25576_0703 Datasheet
434Kb / 24P
   SIMPLE SWITCHER짰 42V, 3A Step-Down Switching Regulator
logo
Texas Instruments
LM25575QMH TI1-LM25575QMH Datasheet
999Kb / 30P
[Old version datasheet]   LM25575/LM25575-Q1 SIMPLE SWITCHER짰 42V, 1.5A Step-Down Switching Regulator
LM25574 TI1-LM25574_14 Datasheet
929Kb / 30P
[Old version datasheet]   SIMPLE SWITCHER짰 42V, 0.5A Step-Down Switching Regulator
LM25575 TI-LM25575 Datasheet
999Kb / 30P
[Old version datasheet]   LM25575/LM25575-Q1 SIMPLE SWITCHER짰 42V, 1.5A Step-Down Switching Regulator
logo
National Semiconductor ...
LM25574_0703 NSC-LM25574_0703 Datasheet
414Kb / 22P
   SIMPLE SWITCHER짰 42V, 0.5A Step-Down Switching Regulator
logo
Texas Instruments
LM25575 TI1-LM25575_14 Datasheet
989Kb / 29P
[Old version datasheet]   SIMPLE SWITCHER짰 42V, 1.5A Step-Down Switching Regulator
LM22676 TI-LM22676_13 Datasheet
2Mb / 27P
[Old version datasheet]   LM22676/LM22676-Q1 42V, 3A SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
LM5576 TI1-LM5576_13 Datasheet
1Mb / 30P
[Old version datasheet]   SIMPLE SWITCHER짰 75V, 3A Step-Down Switching Regulator
LM25576 TI1-LM25576_17 Datasheet
1Mb / 29P
[Old version datasheet]   SIMPLE SWITCHER 42V, 3A Step-Down Switching 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


Fiches technique Télécharger

Go To PDF Page


Lien URL




Politique de confidentialité
ALLDATASHEET.FR
ALLDATASHEET vous a-t-il été utile ?  [ DONATE ] 

À propos de Alldatasheet   |   Publicité   |   Contactez-nous   |   Politique de confidentialité   |   Echange de liens   |   Fabricants
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