công cụ tìm kiếm bảng dữ liệu linh kiện điện tử
  Vietnamese  ▼
ALLDATASHEET.VN

X  

LM25011MY bảng dữ liệu(PDF) 11 Page - Texas Instruments

tên linh kiện LM25011MY
Giải thích chi tiết về linh kiện  42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit
Download  27 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
nhà sản xuất  TI [Texas Instruments]
Trang chủ  http://www.ti.com
Logo TI - Texas Instruments

LM25011MY bảng dữ liệu(HTML) 11 Page - Texas Instruments

Back Button LM25011MY Datasheet HTML 7Page - Texas Instruments LM25011MY Datasheet HTML 8Page - Texas Instruments LM25011MY Datasheet HTML 9Page - Texas Instruments LM25011MY Datasheet HTML 10Page - Texas Instruments LM25011MY Datasheet HTML 11Page - Texas Instruments LM25011MY Datasheet HTML 12Page - Texas Instruments LM25011MY Datasheet HTML 13Page - Texas Instruments LM25011MY Datasheet HTML 14Page - Texas Instruments LM25011MY Datasheet HTML 15Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 27 page
background image
RT =
VOUT - (VIN x FS x 15 ns)
FS x 4.1 x 10
-11
- 500:
tON =
(VIN)
4.1 x 10
-11
x (RT + 500:)
+ 15 ns
LM25011, LM25011-Q1
www.ti.com
SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013
Ripple voltage, which is required at the input of the regulation comparator for proper output regulation, is
generated internally in the LM25011, and externally when the LM25011A is used. In the LM25011 the ERM
(Emulated Ripple Mode) control circuit generates the required internal ripple voltage from the ripple waveform at
the CS pin. The LM25011A, which is designed for higher frequency operation, requires additional ripple voltage,
which must be generated externally and provided to the FB pin. This is described in the Applications Information
section.
ON-TIME TIMER
The on-time for the LM25011/LM25011A is determined by the RT resistor and the input voltage (VIN), calculated
from:
(5)
The inverse relationship with VIN results in a nearly constant frequency as VIN is varied. To set a specific
continuous conduction mode switching frequency (FS), the RT resistor is determined from the following:
(6)
The on-time must be chosen greater than 90 ns for proper operation. Equation 1, Equation 5, and Equation 6 are
valid only during normal operation; that is, the circuit is not in current limit. When the LM25011 operates in
current limit, the on-time is reduced by approximately 40% (this feature is not present in LM25011A). This feature
reduces the peak inductor current which may be excessively high if the load current and the input voltage are
simultaneously high. This feature operates on a cycle-by-cycle basis until the load current is reduced and the
output voltage resumes its normal regulated value. The maximum continuous current into the RT pin must be
less than 2 mA. For high frequency applications, the maximum switching frequency is limited at the maximum
input voltage by the minimum on-time one-shot period (90 ns). At minimum input voltage the maximum switching
frequency is limited by the minimum off-time one-shot period, which, if reached, prevents achievement of the
proper duty cycle.
CURRENT LIMIT
Current limit detection occurs during the off-time by monitoring the voltage across the external current sense
resistor RS. Referring to the Block Diagram, during the off-time the recirculating current flows through the
inductor, through the load, through the sense resistor, and through D1 to the inductor. If the voltage across the
sense resistor exceeds the threshold (VILIM) the current limit comparator output switches to delay the start of the
next on-time period. The next on-time starts when the recirculating current decreases such that the voltage
across RS reduces to the threshold and the voltage at FB is below 2.51V. The operating frequency is typically
lower due to longer-than-normal off-times. When current limit is detected, the on-time is reduced by
approximately 40% (only in LM25011) if the voltage at the FB pin is below its threshold when the voltage across
RS reduces to its threshold (VOUT is low due to current limiting).
Figure 18 illustrates the inductor current waveform during normal operation and in current limit. During the first
“Normal Operation” the load current is I01, the average of the inductor current waveform. As the load resistance is
reduced, the inductor current increases until the lower peak of the inductor ripple current exceeds the threshold.
During the “Current Limited” portion of Figure 18, each on-time is reduced by approximately 40%, resulting in
lower ripple amplitude for the inductor’s current. During this time the LM25011 is in a constant current mode with
an average load current equal to the current limit threshold plus half the ripple amplitude (IOCL), and the output
voltage is below the normal regulated value. Normal operation resumes when the load current is reduced (to IO2),
allowing VOUT and the on-time to return to their normal values. Note that in the second period of “Normal
Operation”, even though the inductor’s peak current exceeds the current limit threshold during part of each cycle,
the circuit is not in current limit since the inductor current falls below the current limit threshold during each off
time. The peak current allowed through the buck switch is 3.5A, and the maximum allowed average current is
2.0A.
Copyright © 2009–2013, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM25011 LM25011-Q1


Số phần tương tự - LM25011MY

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
National Semiconductor ...
LM25011MY NSC-LM25011MY 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
LM25011MY/NOPB TI-LM25011MY/NOPB Datasheet
1Mb / 29P
[Old version datasheet]   LM25011, LM25011-Q1, LM25011A, LM25011A-Q1 42-V 2-A Constant On-Time Switching Regulator With Adjustable Current Limit
logo
National Semiconductor ...
LM25011MYX NSC-LM25011MYX Datasheet
417Kb / 16P
   42V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
logo
Texas Instruments
LM25011MYX TI-LM25011MYX Datasheet
1Mb / 27P
[Old version datasheet]   42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit
More results

Mô tả tương tự - LM25011MY

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
National Semiconductor ...
LM25011 NSC-LM25011 Datasheet
417Kb / 16P
   42V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
logo
Texas Instruments
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
LM34922 TI-LM34922_15 Datasheet
1Mb / 19P
[Old version datasheet]   28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
LM34922 TI1-LM34922 Datasheet
346Kb / 17P
[Old version datasheet]   28V, 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
LM25085A TI1-LM25085A_15 Datasheet
1Mb / 31P
[Old version datasheet]   42V Constant On-Time PFET Buck Switching Controller
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


bảng dữ liệu tải về

Go To PDF Page


Link URL




Chính sách bảo mật
ALLDATASHEET.VN
Cho đến nay ALLDATASHEET có giúp ích cho doanh nghiệp của bạn hay không?  [ DONATE ] 

Alldatasheet là   |   Quảng cáo   |   Liên lạc với chúng tôi   |   Chính sách bảo mật   |   Trao đổi link   |   Tìm kiếm theo nhà sản xuất
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