Motore di ricerca datesheet componenti elettronici
  Italian  ▼
ALLDATASHEETIT.COM

X  

LM22677 Scheda tecnica(PDF) 11 Page - Texas Instruments

Click here to check the latest version.
Il numero della parte LM22677
Spiegazioni elettronici  LM22677/-Q1 42-V, 5-A SIMPLE SWITCHER짰, Step-Down Voltage Regulator With Features
Download  28 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Produttore elettronici  TI [Texas Instruments]
Homepage  http://www.ti.com
Logo TI - Texas Instruments

LM22677 Scheda tecnica(HTML) 11 Page - Texas Instruments

Back Button LM22677 Datasheet HTML 7Page - Texas Instruments LM22677 Datasheet HTML 8Page - Texas Instruments LM22677 Datasheet HTML 9Page - Texas Instruments LM22677 Datasheet HTML 10Page - Texas Instruments LM22677 Datasheet HTML 11Page - Texas Instruments LM22677 Datasheet HTML 12Page - Texas Instruments LM22677 Datasheet HTML 13Page - Texas Instruments LM22677 Datasheet HTML 14Page - Texas Instruments LM22677 Datasheet HTML 15Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 28 page
background image
LM22677
LM22677
RT/SYNC
Vout
1 k
2N7002
EN
ENABLE
1 k
RT/SYNC
EN
LM22677, LM22677-Q1
www.ti.com
SNVS582O – SEPTEMBER 2008 – REVISED AUGUST 2015
Feature Description (continued)
7.3.4 Self Synchronization
It is possible to synchronize multiple LM22677 regulators together to share the same switching frequency. This
can be done by tying the RT/SYNC pins together through a MOSFET and connecting a 1 k
Ω resistor to ground
at each pin. Figure 13 shows this connection. The gate of the MOSFET should be connected to the regulator
with the highest output voltage. Also, the EN pins of both regulators should be tied to the common system
enable, in order to properly initialize both regulators. The operation is as follows: When the regulators are
enabled, the outputs are low and the MOSFET is off. The 1 k
Ω resistors pull the RT/SYNC pins low, thus
enabling the synchronization mode. These resistors are small enough to pull the RT/SYNC pin low, rather than
activate the frequency adjust mode. Once the output voltage of one of the regulators is sufficient to turn on the
MOSFET, the two RT/SYNC pins are tied together and the regulators will run in synchronization mode. The two
regulators will be clocked at the same frequency but slightly phase shifted according to the minimum off-time of
the regulator with the fastest internal oscillator. The slight phase shift helps to reduce stress on the input
capacitors of the regulator. It is important to choose a MOSFET with a low gate threshold voltage so that the
MOSFET will be fully enhanced. Also, a MOSFET with low inter-electrode capacitance is required. The 2N7002
is a good choice.
Figure 13. Self Synchronizing Setup
7.3.5 Boot-Strap Supply
The LM22677 incorporates a floating high-side gate driver to control the power MOSFET. The supply for this
driver is the external boot-strap capacitor connected between the BOOT pin and SW. A good quality 10 nF
ceramic capacitor must be connected to these pins with short, wide PCB traces. One reason the regulator
imposes a minimum off-time is to ensure that this capacitor recharges every switching cycle. A minimum load of
about 5 mA is required to fully recharge the boot-strap capacitor in the minimum off-time. Some of this load can
be provided by the output voltage divider, if used.
7.3.6 Internal Compensation
The LM22677 has internal loop compensation designed to provide a stable regulator over a wide range of
external power stage components. The internal compensation of the -ADJ option is optimized for output voltages
below 5 V. If an output voltage of 5 V or greater is needed, the -5.0 option with an external resistor divider can be
used.
Ensuring stability of a design with a specific power stage (inductor and output capacitor) can be tricky. The
LM22677 stability can be verified using the WEBENCH Designer online circuit simulation tool. A quick start
spreadsheet can also be downloaded from the online product folder.
The complete transfer function for the regulator loop is found by combining the compensation and power stage
transfer functions. The LM22677 has internal type III loop compensation, as detailed in Figure 14. This is the
approximate "straight line" function from the FB pin to the input of the PWM modulator. The power stage transfer
function consists of a dc gain and a second order pole created by the inductor and output capacitor(s). Due to
the input voltage feedforward employed in the LM22677, the power stage dc gain is fixed at 20 dB. The second
order pole is characterized by its resonant frequency and its quality factor (Q). For a first pass design, the
product of inductance and output capacitance should conform to Equation 3.
(3)
Copyright © 2008–2015, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM22677 LM22677-Q1


Codice articolo simile - LM22677

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
National Semiconductor ...
LM22677 NSC-LM22677 Datasheet
404Kb / 16P
   5A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency
LM22677 NSC-LM22677 Datasheet
408Kb / 16P
   5A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency
LM22677Q NSC-LM22677Q Datasheet
408Kb / 16P
   5A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency
LM22677QTJ-5.0 NSC-LM22677QTJ-5.0 Datasheet
408Kb / 16P
   5A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency
LM22677QTJ-ADJ NSC-LM22677QTJ-ADJ Datasheet
408Kb / 16P
   5A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Synchronization or Adjustable Switching Frequency
More results

Descrizione simile - LM22677

Produttore elettroniciIl numero della parteScheda tecnicaSpiegazioni elettronici
logo
Texas Instruments
LM22679 TI-LM22679_15 Datasheet
1Mb / 27P
[Old version datasheet]   LM22679/-Q1 42-V, 5-A SIMPLE SWITCHER짰 Step-Down Voltage Regulator With Features
LM22675 TI-LM22675_15 Datasheet
1Mb / 26P
[Old version datasheet]   LM22675/-Q1 42 V, 1 A SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
LM22676 TI-LM22676_15 Datasheet
1Mb / 29P
[Old version datasheet]   LM22676/-Q1 42 V, 3 A SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
LM22673 TI-LM22673_15 Datasheet
1Mb / 29P
[Old version datasheet]   LM22673/-Q1 42 V, 3 A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Features
LM22670 TI-LM22670_15 Datasheet
1Mb / 32P
[Old version datasheet]   LM22670/-Q1 42 V, 3 A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Features
LM22674 TI-LM22674_15 Datasheet
1Mb / 26P
[Old version datasheet]   LM22674/-Q1 42 V, 500 mA SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
LM22671 TI-LM22671_15 Datasheet
1Mb / 29P
[Old version datasheet]   LM22671/-Q1 42 V, 500 mA SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
LM22672 TI-LM22672_15 Datasheet
1Mb / 30P
[Old version datasheet]   SIMPLE SWITCHER짰 Step-Down Voltage Regulator with Features
logo
National Semiconductor ...
LM22680 NSC-LM22680 Datasheet
568Kb / 16P
   2A SIMPLE SWITCHER짰, Step-Down Voltage Regulator with Features
logo
Texas Instruments
LM22680 TI-LM22680_15 Datasheet
1Mb / 27P
[Old version datasheet]   42 V, 2 A SIMPLE SWITCHER Step-Down Voltage Regulator With Features
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


Scheda tecnica Scarica

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEETIT.COM
Lei ha avuto il aiuto da alldatasheet?  [ DONATE ] 

Di alldatasheet   |   Richest di pubblicita   |   contatti   |   Privacy Policy   |   scambio Link   |   Ricerca produttore
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