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參數(shù)資料
| 型號(hào)： | R1234D181A |
| 廠商： | Ricoh Co., Ltd. |
| 英文描述： | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| 中文描述： | 脈寬調(diào)制/ VFM的降壓型DC / DC同步整流變換器 |
| 文件頁數(shù)： | 14/26頁 |
| 文件大?。?/td> | 876K |
| 代理商： | R1234D181A |
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R1234D
How to Adjust Output Voltage and about Phase Compensation
14
As for Adjustable Output type, feedback pin (V
FB
) voltage is controlled to maintain 0.8V.
Output Voltage, V
OUT
is as following equation;
V
OUT
R1
+
R2
=
V
FB
:R2
V
OUT
=
V
FB
×
(R1
+
R2)/R2
Thus, with changing the value of R1 and R2, output voltage can be set in the specified range.
In the DC/DC converter, with the load current and external components such as L and C, phase might be
behind 180 degree. In this case, the phase margin of the system will be less and stability will be worse. To
prevent this, phase margin should be secured with proceeding the phase. A pole is formed with external
components L and C
OUT
.
LC
1/2
fpole
π
A zero (signal back to zero) is formed with R1 and Cb.
fzero ~ 1/(2
π×
R1
×
Cb)
First, choose the appropriate value of R1, R2 and Cb.
Set R1
+
R2 value 100k
or less.
For example, if L
=
10μH, C
OUT
=
10μF, the cut off frequency of the pole is approximately 16kHz.
To make the cut off frequency of the zero higher than 16kHz, set R1
=
42k
and Cb
=
100pF.
If V
OUT
is set at 1.5V, R2
=
48k
is appropriate.
If a ceramic capacitor is desirable as C
OUT
in your application, nonetheless of the usage of both the fixed
output voltage type and adjustable output type, add 0.2
or more resistance to compensate the ESR. Further, if
a ceramic capacitor is desirable to use as C
OUT
without adding another resister to compensate the ESR, phase
should be back drastically. To make it, R2 value should be smaller compared to R1. As a result, the set output
voltage may be large. For example, to make V
OUT
=
1.5V, constants are R1
=
42k
, R2
=
48k
, and Cb
=
100pF. If the
ceramic capacitor is used, under the heavy load condition, oscillation may be result. On the other hand, if R2 =
12k
and V
OUT
=
3.6V, phase back becomes also large, and even if the device is used with a heavy load, the
operation will be stable.
Rb is effective for reducing the noise on V
FB
. However, it is not always necessary. If it is necessary, use a
resistance as much as 30k
as Rb.
OUT
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| R1234D181B | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D191A | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D191B | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D201A | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D201B | PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| R1234D181B | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D191A | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D191B | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D201A | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
| R1234D201B | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier |
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