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

X  

CD43-4R7 数据表(PDF) 6 Page - Linear Technology

部件名 CD43-4R7
功能描述  Dual Micropower DC/DC Converter with Positive and Negative Outputs
Download  8 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
制造商  LINER [Linear Technology]
网页  http://www.linear.com
标志 LINER - Linear Technology

CD43-4R7 数据表(HTML) 6 Page - Linear Technology

  CD43-4R7 Datasheet HTML 1Page - Linear Technology CD43-4R7 Datasheet HTML 2Page - Linear Technology CD43-4R7 Datasheet HTML 3Page - Linear Technology CD43-4R7 Datasheet HTML 4Page - Linear Technology CD43-4R7 Datasheet HTML 5Page - Linear Technology CD43-4R7 Datasheet HTML 6Page - Linear Technology CD43-4R7 Datasheet HTML 7Page - Linear Technology CD43-4R7 Datasheet HTML 8Page - Linear Technology  
Zoom Inzoom in Zoom Outzoom out
 6 / 8 page
background image
6
LT1945
1945f
APPLICATIO S I FOR ATIO
For higher output voltages, the formula above will give
large inductance values. For a 2V to 20V converter (typical
LCD bias application), a 47
µH inductor is called for with
the above equation, but a 10
µH or 22µH inductor could be
used without excessive reduction in maximum output
current.
Inductor Selection—Inverting Charge Pump Regulator
For the inverting regulator, the voltage seen by the internal
power switch is equal to the sum of the absolute value of
the input and output voltages, so that generating high
output voltages from a high input voltage source will often
exceed the 36V maximum switch rating. For instance, a
12V to – 30V converter using the inverting topology would
generate 42V on the SW pin, exceeding its maximum
rating. For this application, an inverting charge pump is
the best topology.
The formula below calculates the approximate inductor
value to be used for an inverting charge pump regulator
using the LT1945. As for the boost inductor selection, a
larger or smaller value can be used. For designs with
varying VIN such as battery powered applications, use the
minimum VIN value in the equation below.
L
VV
V
I
t
OUT
IN MIN
D
LIM
OFF
=
−+
()
Current Limit Overshoot
For the constant off-time control scheme of the LT1945,
the power switch is turned off only after the 350mA current
limit is reached. There is a 100ns delay between the time
when the current limit is reached and when the switch
actually turns off. During this delay, the inductor current
exceeds the current limit by a small amount. The peak
inductor current can be calculated by:
II
VV
L
ns
PEAK
LIM
IN MAX
SAT
=+
()
100
Where VSAT = 0.25V (switch saturation voltage). The
current overshoot will be most evident for regulators with
high input voltages and smaller inductor values. This
overshoot can be beneficial as it helps increase the amount
of available output current for smaller inductor values.
This will be the peak current seen by the inductor (and the
diode) during normal operation. For designs using small
inductance values (especially at input voltages greater
than 5V), the current limit overshoot can be quite high.
Although it is internally current limited to 350mA, the
power switch of the LT1945 can handle larger currents
without problem, but the overall efficiency will suffer. Best
results will be obtained when IPEAK is kept below 700mA
for the LT1945.
Capacitor Selection
Low ESR (Equivalent Series Resistance) capacitors should
be used at the output to minimize the output ripple voltage.
X5R or X7R multilayer ceramic capacitors are the best
choice, as they have a very low ESR and are available in
very small packages. Y5V ceramics are not recommended.
Their small size makes them a good companion to the
LT1945’s MS10 package. Solid tantalum capacitors (like
the AVX TPS, Sprague 593D families) or OS-CON capaci-
tors can be used, but they will occupy more board area
than a ceramic and will have a higher ESR. Always use a
capacitor with a sufficient voltage rating.
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close as
possible to the LT1945. A 4.7
µF input capacitor is suffi-
cient for most applications. Table 2 shows a list of several
capacitor manufacturers. Consult the manufacturers for
more detailed information and for their entire selection of
related parts.
Table 2. Recommended Capacitors
CAPACITOR TYPE
VENDOR
Ceramic
Taiyo Yuden
(408) 573-4150
www.t-yuden.com
Ceramic
AVX
(803) 448-9411
www.avxcorp.com
Ceramic
Murata
(714) 852-2001
www.murata.com


类似零件编号 - CD43-4R7

制造商部件名数据表功能描述
logo
AIT Components Ltd.
CD43-4R7 AITCOMPONENTS-CD43-4R7 Datasheet
31Kb / 1P
   CD43 SMD POWER INDUCTOR
More results

类似说明 - CD43-4R7

制造商部件名数据表功能描述
logo
Linear Technology
LT1945 LINER-LT1945_15 Datasheet
131Kb / 8P
   Dual Micropower DC/DC Converter with Positive and Negative Outputs
logo
Texas Instruments
TPS65130 TI-TPS65130 Datasheet
550Kb / 29P
[Old version datasheet]   POSITIVE AND NEGATIVE OUTPUT DC-DC CONVERTER
TPS65130RGER TI1-TPS65130RGER Datasheet
1Mb / 34P
[Old version datasheet]   POSITIVE AND NEGATIVE OUTPUT DC-DC CONVERTER
TPS65130 TI1-TPS65130_16 Datasheet
1Mb / 32P
[Old version datasheet]   Positive and Negative Output DC-DC Converter
TPS65130RGER TI-TPS65130RGER Datasheet
1Mb / 34P
[Old version datasheet]   POSITIVE AND NEGATIVE OUTPUT DC-DC CONVERTER
TPS65131-Q1 TI1-TPS65131-Q1 Datasheet
1Mb / 33P
[Old version datasheet]   Positive- and Negative-Output DC-DC Converter
TPS65130 TI-TPS65130_15 Datasheet
1Mb / 32P
[Old version datasheet]   TPS6513x Positive and Negative Output DC-DC Converter
logo
Maxim Integrated Produc...
MAX685 MAXIM-MAX685_V01 Datasheet
350Kb / 11P
   Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD
2003
logo
TOKO, Inc
TK11835 TOKO-TK11835 Datasheet
13Kb / 1P
   POSITIVE TO NEGATIVE DC-DC CONVERTER
TK11830 TOKO-TK11830 Datasheet
85Kb / 13P
   POSITIVE-TO-NEGATIVE DC-DC CONVERTER
More results


Html Pages

1 2 3 4 5 6 7 8


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