- 您现在的位置：买卖IC网 > PDF目录381300 > APW7077ARBI-TU (Anpec Electronics Corporation) PWM Step-Up DC-DC Converter PDF资料下载
参数资料
| 型号： | APW7077ARBI-TU |
| 厂商： | Anpec Electronics Corporation |
| 元件分类： | DC/DC变换器 |
| 英文描述： | PWM Step-Up DC-DC Converter |
| 中文描述： | PWM升压型DC - DC转换器 |
| 文件页数： | 13/21页 |
| 文件大小： | 444K |
| 代理商： | APW7077ARBI-TU |
Copyright
ANPEC Electronics Corp.
Rev. A.4 - S ep, 2005
APW 7077/ A
www.anpec.com.tw
13
Function Description ( Cont.)
OUT
IN
OUT
V
V
V
D
=
In higher output voltage or small output current
application, the step–up DC–DC controller operated in
discontinuous conduction mode almost. For a step-up
converter in a DCM, the duty cycle D is given by
External components values can be calculated from
these equations, however, the optimized value should
obtained through experimental results.
Critical Inductance Value
The minimum value of inductor to maintain continuous
conduction mode can be determined by the following
equation.
Ratio
I
fsw
D)
D(1
V
L
O
2
OUT
×
×
×
≥
A system can be designed to operate in continuous
mode for load currents above a certain level usually
20 to 50% (Ratio define as 0.2~0.5) of full load at
minimum input voltage. When I
O
smaller than (I
O
*Ratio),
the controller system will into DCM.
I
L
is the ripple current flowing through the inductor,
which affects the output voltage ripple and core losses.
Based on 20%(Ratio=0.2) current ripple, V
OUT
=5V,
I
O
=1A and V
IN
=1.8V system, the inductance value is
calculated as 6.9uH and a 6.8uH inductor is used.
The inductor current ripple has an expression
D
V
I
L
×
The maximum DC input current can be calculated as
L
fsw
IN
×
=
(min)
V
(max)
I
V
(max)
I
IN
O
OUT
L
×
=
The inductor peak current can be calculated as
×
=
2
I
V
I
V
Ipk
L
O
OUT
IN
+
NOTES:
D – On–time duty cycle
I
L
– Average inductor current
I
PK
– Peak inductor current
I
O
– Desired dc output current
V
IN
– Nominal operating dc input voltage
V
OUT
– Desired dc output voltage
ESR – Equivalent series resistance of the output
capacitor
Inductor Selection
APW7077/A series are designed to work well with a
6.8 to 12uH inductors in most applications 10uH is a
sufficiently low value to allow the use of a small
surface mount coil, but large enough to maintain low
ripple. Lower inductance values supply higher output
current, but also increase the ripple and reduce
efficiency. Higher inductor values reduce ripple and
improve efficiency, but also limit output current. The
inductor should have small DCR, usually less than
1m
, to minimize loss. It is necessary to choose an
inductor with a saturation current greater than the peak
current which the inductor will encounter in the
application.
The inductor ripple current is important for a few
reasons. One reason is because the peak switch
current will be the average inductor current (I
L
) plus
I
L
.
As a side note, discontinuous operation occurs when
the inductor current falls to zero during a switching
cycle, or
I
L
is greater than the average inductor
current. Therefore, continuous conduction mode occurs
=
1
V
V
V
V
R
T
L
2
D
IN
OUT
IN
OUT
LOAD
S
given by
Step–up Converter Operating Mode (Cont.)
相关PDF资料 |
PDF描述 |
|---|---|
| APW7077ARBI-TUL | PWM Step-Up DC-DC Converter |
| APW7077AZBI-TR | PWM Step-Up DC-DC Converter |
| APW7077AZBI-TRL | PWM Step-Up DC-DC Converter |
| APW7077AZBI-TU | PWM Step-Up DC-DC Converter |
| APW7078 | Single Step-up DC/DC Controller |
相关代理商/技术参数 |
参数描述 |
|---|---|
| APW7077ARBI-TUL | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077AZBI-TR | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077AZBI-TRL | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077AZBI-TU | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077AZBI-TUL | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
发布紧急采购，3分钟左右您将得到回复。