数据搜索系统,热门电子元器件搜索
  Chinese  ▼
ALLDATASHEETCN.COM

X  

LM2578 数据表(PDF) 9 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
部件名 LM2578
功能描述  Switching Regulator
Download  18 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
制造商  NSC [National Semiconductor (TI)]
网页  http://www.national.com
标志 NSC - National Semiconductor (TI)

LM2578 数据表(HTML) 9 Page - National Semiconductor (TI)

Back Button LM2578 Datasheet HTML 5Page - National Semiconductor (TI) LM2578 Datasheet HTML 6Page - National Semiconductor (TI) LM2578 Datasheet HTML 7Page - National Semiconductor (TI) LM2578 Datasheet HTML 8Page - National Semiconductor (TI) LM2578 Datasheet HTML 9Page - National Semiconductor (TI) LM2578 Datasheet HTML 10Page - National Semiconductor (TI) LM2578 Datasheet HTML 11Page - National Semiconductor (TI) LM2578 Datasheet HTML 12Page - National Semiconductor (TI) LM2578 Datasheet HTML 13Page - National Semiconductor (TI) Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 18 page
background image
Applications Information (Continued)
REMOTE SHUTDOWN
The LM1578A may be remotely shutdown by sinking a
greater current from the non-inverting input than from the in-
verting input. This may be accomplished by selecting resistor
R3 to be approximately one-half the value of R1 and R2 in
parallel.
EMITTER OUTPUT
When the LM1578A output transistor is in the OFF state, if
the Emitter output swings below the ground pin voltage, the
output transistor will turn ON because its base is clamped
near ground. The
Collector Current with Emitter Output Be-
low Ground curve shows the amount of Collector current
drawn in this mode, vs temperature and Emitter voltage.
When the Collector-Emitter voltage is high, this current will
cause high power dissipation in the output transistor and
should be avoided.
This situation can occur in the high-current high-voltage
buck application if the Emitter output is used and the catch
diode’s forward voltage drop is greater than 0.6V. A
fast-recovery diode can be added in series with the Emitter
output to counter the forward voltage drop of the catch diode
(see
Figure 2). For better efficiency of a high output current
buck regulator, an external PNP transistor should be used as
shown in
Figure 16.
SYNCHRONIZING DEVICES
When several devices are to be operated at once, their oscil-
lators may be synchronized by the application of an external
signal. This drive signal should be a pulse waveform with a
minimum pulse width of 2 µs. and an amplitude from 1.5V to
2.0V. The signal source must be capable of 1.) driving ca-
pacitive loads and 2.) delivering up to 500 µA for each
LM1578A.
Capacitors C1 thru CN are to be selected for a 20% slower
frequency than the synchronization frequency.
Typical Applications
The LM1578A may be operated in either the continuous or
the discontinuous conduction mode. The following applica-
tions (except for the Buck-Boost Regulator) are designed for
continuous conduction operation. That is, the inductor cur-
rent is not allowed to fall to zero. This mode of operation has
higher efficiency and lower EMI characteristics than the dis-
continuous mode.
BUCK REGULATOR
The buck configuration is used to step an input voltage down
to a lower level. Transistor Q1 in
Figure 14 chops the input
DC voltage into a squarewave. This squarewave is then con-
verted back into a DC voltage of lower magnitude by the low
pass filter consisting of L1 and C1. The duty cycle, D, of the
squarewave relates the output voltage to the input voltage by
the following equation:
V
out = DxVin = Vin x(ton)/(ton +toff).
DS008711-23
FIGURE 10. Duty Cycle Adjustment
DS008711-24
FIGURE 11. Shutdown Occurs when V
L is High
DS008711-30
FIGURE 12. D1 Prevents Output Transistor from
Improperly Turning ON due to D2’s Forward Voltage
DS008711-25
FIGURE 13. Synchronizing Devices
9
www.national.com


类似零件编号 - LM2578

制造商部件名数据表功能描述
logo
National Semiconductor ...
LM2578A NSC-LM2578A Datasheet
1Mb / 20P
   Switching Regulator
logo
Texas Instruments
LM2578A TI-LM2578A Datasheet
1Mb / 30P
[Old version datasheet]   LM2578A/LM3578A Switching Regulator
LM2578A TI1-LM2578A Datasheet
1Mb / 30P
[Old version datasheet]   Switching Regulator
LM2578AM TI-LM2578AM Datasheet
1Mb / 30P
[Old version datasheet]   LM2578A/LM3578A Switching Regulator
LM2578AM TI1-LM2578AM Datasheet
1Mb / 30P
[Old version datasheet]   Switching Regulator
More results

类似说明 - LM2578

制造商部件名数据表功能描述
logo
Toshiba Semiconductor
TPC8012-H TOSHIBA-TPC8012-H_06 Datasheet
270Kb / 7P
   Switching Regulator Applications Switching Regulator Applications
logo
Texas Instruments
PT7778-3.3V TI1-PT7778-3.3V Datasheet
183Kb / 4P
[Old version datasheet]   Switching Regulator
logo
Sanyo Semicon Device
LA5757TP SANYO-LA5757TP Datasheet
78Kb / 6P
   Switching Regulator
logo
National Semiconductor ...
LM3578A NSC-LM3578A Datasheet
1Mb / 20P
   Switching Regulator
logo
Sanyo Semicon Device
LA5756 SANYO-LA5756 Datasheet
125Kb / 4P
   Switching Regulator
logo
ON Semiconductor
CS5111 ONSEMI-CS5111 Datasheet
112Kb / 16P
   Switching Regulator
January, 2001 ??Rev. 9
logo
National Semiconductor ...
LM2579 NSC-LM2579 Datasheet
540Kb / 13P
   SWITCHING REGULATOR
logo
Texas Instruments
LM2578A TI1-LM2578A Datasheet
1Mb / 30P
[Old version datasheet]   Switching Regulator
logo
ON Semiconductor
LA5774MC ONSEMI-LA5774MC Datasheet
313Kb / 6P
   Switching Regulator
May,2013
logo
XP Power Limited
STR XPPOWER-STR Datasheet
360Kb / 4P
   Switching Regulator
More results


Html Pages

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


数据表 下载

Go To PDF Page


链接网址




隐私政策
ALLDATASHEETCN.COM
ALLDATASHEET是否为您带来帮助?  [ DONATE ] 

关于 Alldatasheet   |   广告服务   |   联系我们   |   隐私政策   |   链接交换   |   制造商名单
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