Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

LM25019SDE Datasheet(PDF) 10 Page - Texas Instruments

Part # LM25019SDE
Description  100-mA Constant On-Time Synchronous Buck Regulator
Download  28 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  TI1 [Texas Instruments]
Direct Link  http://www.ti.com
Logo TI1 - Texas Instruments

LM25019SDE Datasheet(HTML) 10 Page - Texas Instruments

Back Button LM25019SDE Datasheet HTML 6Page - Texas Instruments LM25019SDE Datasheet HTML 7Page - Texas Instruments LM25019SDE Datasheet HTML 8Page - Texas Instruments LM25019SDE Datasheet HTML 9Page - Texas Instruments LM25019SDE Datasheet HTML 10Page - Texas Instruments LM25019SDE Datasheet HTML 11Page - Texas Instruments LM25019SDE Datasheet HTML 12Page - Texas Instruments LM25019SDE Datasheet HTML 13Page - Texas Instruments LM25019SDE Datasheet HTML 14Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 10 / 28 page
background image
FB
SW
L1
COUT
RFB2
VOUT
RC
LM25019
+
RFB1
VOUT
(low ripple)
RFB2 + RFB1
VOUT = 1.225V x
RFB1
OUT
SW
11
ON
V
f
9 10
R
u
u
LM25019
SNVS952E – DECEMBER 2012 – REVISED NOVEMBER 2015
www.ti.com
7.3 Feature Description
7.3.1 Control Overview
The LM25019 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 (1.225 V). If the FB voltage is below the
reference the internal buck switch is turned on for the one-shot timer period, which is a function of the input
voltage and the programming resistor (RON). Following the on-time the switch remains off until the FB voltage
falls below the reference, but never before the minimum off-time forced by the minimum off-time one-shot timer.
When the FB pin voltage falls below the reference and the minimum off-time one-shot period expires, the buck
switch is turned on for another on-time one-shot period. This will continue until regulation is achieved and the FB
voltage is approximately equal to 1.225 V (typ).
In a synchronous buck converter, the low-side (sync) FET is on when the high-side (buck) FET is off. The
inductor current ramps up when the high-side switch is on and ramps down when the high-side switch is off.
There is no diode emulation feature in this IC, and therefore, the inductor current may ramp in the negative
direction at light load. This causes the converter to operate in continuous conduction mode (CCM) regardless of
the output loading. The operating frequency remains relatively constant with load and line variations. The
operating frequency can be calculated as shown in Equation 1.
(1)
The output voltage (VOUT) is set by two external resistors (RFB1, RFB2). The regulated output voltage is calculated
as shown in Equation 2.
(2)
This regulator regulates the output voltage based on ripple voltage at the feedback input, requiring a minimum
amount of ESR for the output capacitor (COUT). A minimum of 25 mV of ripple voltage at the feedback pin (FB) is
required for the LM25019. In cases where the capacitor ESR is too small, additional series resistance may be
required (RC in Figure 11).
For applications where lower output voltage ripple is required the output can be taken directly from a low ESR
output capacitor, as shown in Figure 11. However, RC slightly degrades the load regulation.
Figure 11. Low Ripple Output Configuration
7.3.2 VCC Regulator
The LM25019 device contains an internal high-voltage linear regulator with a nominal output of 7.6 V. The input
pin (VIN) can be connected directly to the line voltages up to 48 V. The VCC regulator is internally current limited
to 30 mA. The regulator sources current into the external capacitor at VCC. This regulator supplies current to
internal circuit blocks including the synchronous MOSFET driver and the logic circuits. When the voltage on the
VCC pin reaches the UVLO threshold of 4.5 V, the IC is enabled.
The VCC regulator contains an internal diode connection to the BST pin to replenish the charge in the gate drive
boot capacitor when SW pin is low.
At high input voltages, the power dissipated in the high-voltage regulator is significant and can limit the overall
achievable output power. As an example, with the input at 48 V and switching at high frequency, the VCC
regulator may supply up to 7 mA of current resulting in 48 V × 7 mA = 336 mW of power dissipation. If the VCC
voltage is driven externally by an alternate voltage source, between 8.55 V and 13 V, the internal regulator is
disabled. This reduces the power dissipation in the IC.
10
Submit Documentation Feedback
Copyright © 2012–2015, Texas Instruments Incorporated
Product Folder Links: LM25019


Similar Part No. - LM25019SDE

ManufacturerPart #DatasheetDescription
logo
Texas Instruments
LM25019SDE/NOPB TI-LM25019SDE/NOPB Datasheet
331Kb / 18P
[Old version datasheet]   48V, 100mA Constant On-Time Synchronous Buck Regulator
More results

Similar Description - LM25019SDE

ManufacturerPart #DatasheetDescription
logo
Texas Instruments
LM5019 TI-LM5019_15 Datasheet
1Mb / 30P
[Old version datasheet]   100-V, 100-mA Constant On-Time Synchronous Buck Regulator
LM5019 TI1-LM5019_14 Datasheet
1Mb / 25P
[Old version datasheet]   100 V, 100 mA Constant On-Time Synchronous Buck Regulator
LM5017 TI-LM5017_15 Datasheet
1Mb / 31P
[Old version datasheet]   100-V, 600-mA Constant On-Time Synchronous Buck Regulator
LM5018 TI1-LM5018_13 Datasheet
1Mb / 25P
[Old version datasheet]   100 V, 300 mA Constant On-Time Synchronous Buck Regulator
LM5018 TI-LM5018_15 Datasheet
1Mb / 32P
[Old version datasheet]   100-V, 300-mA Constant On-Time Synchronous Buck Regulator
LM25019 TI-LM25019_15 Datasheet
1Mb / 27P
[Old version datasheet]   LM25019 48-V, 100-mA Constant On-Time Synchronous Buck Regulator
LM5017 TI1-LM5017_17 Datasheet
1Mb / 33P
[Old version datasheet]   LM5017 100-V, 600-mA Constant On-Time Synchronous Buck Regulator
LM5008A TI-LM5008A Datasheet
1Mb / 23P
[Old version datasheet]   100-V 350-mA Constant On-Time Buck Switching Regulator
LM5017MRX_NOPB TI1-LM5017MRX_NOPB Datasheet
1Mb / 19P
[Old version datasheet]   600mA Constant On-Time Synchronous Buck Regulator
LM5008A TI-LM5008A_15 Datasheet
1Mb / 24P
[Old version datasheet]   100-V 350-mA Constant On-Time Buck 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


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