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| 型號： | HA17431UA |
| 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)： | 19/26頁 |
| 文件大小： | 236K |
| 代理商： | HA17431UA |
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HA17431 Series
Rev.1, Sep. 2002, page 17 of 24
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
HA17431
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 HA17431 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 HA17431 reference input current Iref and the AC
characteristics described in the next section. The Iref value is around 3.8
μ
A Typ. (V version: 2
μ
A Typ)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| HA17431UPA | Regarding the change of names mentioned in the document, such as Hitachi Electric and Hitachi XX, to Renesas Technology Corp. |
| HA17431VUP | Infrared Temperature Sensor; Sensor Output Type:K thermocouple; Field of View:10:1; Sensor Terminals:Cable; Accuracy: 1%; Features:Miniature Sensing Head with separate electronics; Response Time:200ms; Supply Voltage:24VDC |
| HA17431H | Shunt Regulator |
| HA17431HLP | Shunt Regulator |
| HA17431HLTP | Shunt Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HA17431UA-E | 制造商:Renesas Electronics Corporation 功能描述:HA17431UA-E |
| HA17431UA-TL | 制造商:Hitachi 功能描述:Voltage Regulator, Adjustable, +2.5 TO +40V, Bi-Polar, 3 Pin, Plastic, TO-243 |
| HA17431UA-TL-E | 制造商:Renesas Electronics 功能描述:Precision Cut Tape 制造商:Renesas Electronics Corporation 功能描述:Shunt Regulator,2.495V 2.2%,150mA,UPAKV 制造商:Renesas 功能描述:V-Ref Adjustable 150mA 4-Pin(3+Tab) UPAKV |
| HA17431UPA | 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. |
| HA17431VLP | 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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