Motor de Búsqueda de Datasheet de Componentes Electrónicos
  Spanish  ▼
ALLDATASHEET.ES

X  

LM34922 Datasheet(PDF) 9 Page - Texas Instruments

No. de pieza LM34922
Descripción Electrónicos  28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
Download  19 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricante Electrónico  TI [Texas Instruments]
Página de inicio  http://www.ti.com
Logo TI - Texas Instruments

LM34922 Datasheet(HTML) 9 Page - Texas Instruments

Back Button LM34922_15 Datasheet HTML 5Page - Texas Instruments LM34922_15 Datasheet HTML 6Page - Texas Instruments LM34922_15 Datasheet HTML 7Page - Texas Instruments LM34922_15 Datasheet HTML 8Page - Texas Instruments LM34922_15 Datasheet HTML 9Page - Texas Instruments LM34922_15 Datasheet HTML 10Page - Texas Instruments LM34922_15 Datasheet HTML 11Page - Texas Instruments LM34922_15 Datasheet HTML 12Page - Texas Instruments LM34922_15 Datasheet HTML 13Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 19 page
background image
FS =
VOUT
2 x L1 x 1.19 x 1021
RL x RT
2
DC =
tON
tON + tOFF
=
= tON x FS
VOUT
VIN
FS =
VOUT
(4.1 x 10
-11
x (RT + 0.5k)) + (VIN x 15 ns)
LM34922
www.ti.com
SNVS813A – JUNE 2012 – REVISED MARCH 2013
FUNCTIONAL DESCRIPTION
The LM34922 Constant On-time Step-down Switching Regulator features all the functions needed to implement a
low cost, efficient buck bias power converter capable of supplying up to 2.0A to the load. This high voltage
regulator contains an N-Channel buck switch, is easy to implement, and is available in a 10-pin HVSSOP-
PowerPAD power enhanced package. The regulator’s operation is based on a constant on-time control principle
with the on-time inversely proportional to the input voltage. This feature results in the operating frequency
remaining relatively constant with load and input voltage variations. The constant on-time feedback control
principle requires no loop compensation resulting in very fast load transient response. The adjustable valley
current limit detection results in a smooth transition from constant voltage to constant current when current limit is
reached. To aid in controlling excessive switch current due to a possible saturating inductor the on-time is
reduced by
≊40% when current limit is detected. The Power Good output (PGD pin) indicates when the output
voltage is within 5% of the expected regulation voltage.
The LM34922 can be implemented to efficiently step-down higher voltages in non-isolated applications.
Additional features include: Low output ripple, VIN under-voltage lock-out, adjustable soft-start timing, thermal
shutdown, gate drive pre-charge, gate drive under-voltage lock-out, and maximum duty cycle limit.
Control Circuit Overview
The LM34922 buck regulator employs a control principle based on a comparator and a one-shot on-timer, with
the output voltage feedback (FB) compared to an internal reference (2.51V). If the FB voltage is below the
reference the internal buck switch is switched on for the one-shot timer period, which is a function of the input
voltage and the programming resistor (RT). Following the on-time the switch remains off until the FB voltage falls
below the reference, but never less than the minimum off-time forced by the off-time one-shot timer. When the
FB pin voltage falls below the reference and the off-time one-shot period expires, the buck switch is then turned
on for another on-time one-shot period.
When in regulation, the LM34922 operates in continuous conduction mode at heavy load currents and
discontinuous conduction mode at light load currents. In continuous conduction mode the inductor’s current is
always greater than zero, and the operating frequency remains relatively constant with load and line variations.
The minimum load current for continuous conduction mode is one-half the inductor’s ripple current amplitude.
The approximate operating frequency is calculated as follows:
(1)
The buck switch duty cycle is approximately equal to:
(2)
When the load current is less than one half the inductor’s ripple current amplitude the circuit operates in
discontinuous conduction mode. The off-time is longer than in continuous conduction mode while the inductor
current is zero, causing the switching frequency to reduce as the load current is reduced. Conversion efficiency is
maintained at light loads since the switching losses are reduced with the reduction in load and frequency. The
approximate discontinuous operating frequency can be calculated as follows:
where
RL = the load resistance
L1 is the circuit’s inductor
(3)
The output voltage is set by the two feedback resistors (RFB1, RFB2 in the Block Diagram). The regulated output
voltage is calculated as follows:
VOUT = 2.51V x (RFB1 + RFB2) / RFB1
(4)
Copyright © 2012–2013, Texas Instruments Incorporated
Submit Documentation Feedback
9
Product Folder Links: LM34922


Número de pieza similar - LM34922_15

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Texas Instruments
LM34922MY TI1-LM34922MY Datasheet
346Kb / 17P
[Old version datasheet]   28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
LM34922MYX TI1-LM34922MYX Datasheet
346Kb / 17P
[Old version datasheet]   28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
More results

Descripción similar - LM34922_15

Fabricante ElectrónicoNo. de piezaDatasheetDescripción Electrónicos
logo
Texas Instruments
LM34922 TI1-LM34922 Datasheet
346Kb / 17P
[Old version datasheet]   28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
logo
National Semiconductor ...
LM25011 NSC-LM25011 Datasheet
417Kb / 16P
   42V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
logo
Texas Instruments
LM25011MY TI-LM25011MY Datasheet
1Mb / 27P
[Old version datasheet]   42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit
LM25011 TI1-LM25011_14 Datasheet
1Mb / 26P
[Old version datasheet]   42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit
LM25011AQ1MY TI-LM25011AQ1MY Datasheet
1Mb / 27P
[Old version datasheet]   42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit
logo
National Semiconductor ...
LM34930 NSC-LM34930 Datasheet
371Kb / 18P
   Ultra Small 33V, 1A Constant On-Time Buck Switching Regulator with Intelligent Current Limit
logo
Texas Instruments
LM34917A TI1-LM34917A_14 Datasheet
919Kb / 21P
[Old version datasheet]   Ultra Small 33V, 1.25A Constant On-Time Buck Switching Regulator with Intelligent Current Limit
logo
National Semiconductor ...
LM34917A NSC-LM34917A Datasheet
554Kb / 16P
   Ultra Small 33V, 1.25A Constant On-Time Buck Switching Regulator with Intelligent Current Limit
logo
Texas Instruments
LM34917A TI-LM34917A_15 Datasheet
967Kb / 22P
[Old version datasheet]   Ultra Small 33V, 1.25A Constant On-Time Buck Switching Regulator with Intelligent Current Limit
logo
Feeling Technology Corp...
FP7102 FEELING-FP7102 Datasheet
394Kb / 12P
   28V, 2A Buck Constant Current Switching Regulator for White LED
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19


Datasheet Descarga

Go To PDF Page


Enlace URL




Política de Privacidad
ALLDATASHEET.ES
¿ALLDATASHEET es útil para Ud.?  [ DONATE ] 

Todo acerca de Alldatasheet   |   Publicidad   |   Contáctenos   |   Política de Privacidad   |   Intercambio de Enlaces   |   Lista de Fabricantes
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