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參數(shù)資料
| 型號(hào)： | HA17432UPA |
| 廠商： | Hitachi,Ltd. |
| 英文描述： | Regarding the change of names mentioned in the document, such as Hitachi Electric and Hitachi XX, to Renesas Technology Corp. |
| 中文描述： | 關(guān)于在諸如日立電器和日立二十，文件提及的瑞薩科技公司名稱變更 |
| 文件頁數(shù)： | 9/15頁 |
| 文件大小： | 146K |
| 代理商： | HA17432UPA |
HA17431H Series
Rev.0, Sep. 2001, page 9 of 15
Design Guide for AC-DC SMPS
(Switching Mode Power Supply)
Use of Shunt Regulator in Transformer Secondary Side Control
This example is applicable to both forward transformers and flyback transformers. A shunt regulator is
used on the secondary side as an error amplifier, and feedback to the primary side is provided via a
photocoupler.
R
1
R
2
R
3
R
4
Transformer
Photocoupler
Light
emitting diode
Phototransistor
Output
C
1
R
5
REF
GND
A
K
V
K
I
B
I
F
HA17431H
V
F
SBD
PWM IC
HA17384
HA17385
Vref
V
0
(+)
(
–
)
Figure 2 Typical Shunt Regulator/Error Amplifier
Determination of External Constants for the Shunt Regulator
DC characteristic determination:
In figure 2, R
1
and R
2
are protection resistor for the light emitting diode
in the photocoupler, and R
2
is a bypass resistor to feed I
K
minimum, and these are determined as shown
below. The photocoupler specification should be obtained separately from the manufacturer. Using the
parameters in figure 2, the following formulas are obtained:
R
1
=V
0
–
V
F
–
V
K
I
F
+ I
B
, R
2
=V
F
I
B
V
K
is the HA17431H operating voltage, and is set at around 3 V, taking into account a margin for
fluctuation. R
2
is the current shunt resistance for the light emitting diode, in which a bias current I
B
of
around 1/5 I
F
flows.
Next, the output voltage can be determined by R3 and R4, and the following formula is obtained:
V
0
=R
3
+ R
4
R
4
×
Vref, Vref = 2.5 V Typ
The absolute values of R
3
and R
4
are determined by the HA17431H reference input current Iref and the AC
characteristics described in the next section. The Iref value is around 0.6
μ
A Typ.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HA17432VLTP | 制造商:HITACHI 制造商全稱:Hitachi Semiconductor 功能描述:Regarding the change of names mentioned in the document, such as Hitachi Electric and Hitachi XX, to Renesas Technology Corp. |
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| HA17451 | 制造商:HITACHI 制造商全稱:Hitachi Semiconductor 功能描述:Switching Regulator Controllers for DC/DC Converters |
| HA17451AFP | 制造商:HITACHI 制造商全稱:Hitachi Semiconductor 功能描述:Switching Regulator Controllers for DC/DC Converters |
| HA17451AP | 制造商:HITACHI 制造商全稱:Hitachi Semiconductor 功能描述:Switching Regulator Controllers for DC/DC Converters |
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