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参数资料
| 型号： | LA7838 |
| 厂商： | SANYO SEMICONDUCTOR CO LTD |
| 元件分类： | 偏转 |
| 英文描述： | VERTICAL DEFLECTION IC, PSFM13 |
| 封装： | SIP-13 |
| 文件页数： | 8/9页 |
| 文件大小： | 204K |
| 代理商： | LA7838 |
LA7837, 7838
No.3313–8/9
LA7837, 7838 application in a multi-sync system
The LA7837, 7838 can also be used in a vertical frequency multi-sync system.
The LA7837, 7838 do not have an on-chip vertical oscillation circuit, so they operate merely by impressing a trigger
pulse (e.g. 40 to 80Hz) on pin 2.
However, there are two problems with using the LA7837, 7838 as are in a multi-sync system.
One is vertical amplitude. When the trigger pulse changes between 40 to 80Hz, the vertical frequency will rise and
amplitude size decreases (because pin 6 cycle (T1, T2) in the diagram below becomes shorter).
Fig. 8
Countermeasure 1
In order to stabilize vertical size change, an
operational amplifier is used to change the
circuit to one which controls pin 4 vertical
size control current.
Voltage which corresponds to vertical fre-
quency changes is applied to the operational
amplifier to stabilize vertical size.
The other problem is that vertical linearity chages when used at multi-frequency (e.g. 40 to 80Hz).
The reason for this is that R5 and C1 time constants are used for linearity correction (Fig.9), so even though the value
is optimum for a certain frequency, it is not for others.
Countermeasure 2
As shown in Fig.10, good linearity can be obtained by setting frequency ranges of use for R5 and C1 time constants for
vertical linearity correction, and switching them.
For example :
40 to 60Hz Switch A
60 to 80Hz Switch B
For switch A, R5 and C1 are set so that vertical linearity response is optimum for fv
≈50Hz.
Next, for switch B, R5’ and C1’ are set for optimum value at fv
≈70Hz.
By dividing the vertical trigger pulse range (e.g.40 to 80Hz) and performing linearity correction in this way, linearity
distortion can be kept below about 3%.
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PDF描述 |
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| LA7837 | VERTICAL DEFLECTION IC, PSFM13 |
| LA7840 | VERTICAL DEFLECTION IC, PSFM7 |
| LA7840 | VERTICAL DEFLECTION IC, PSFM7 |
| LA7841 | VERTICAL DEFLECTION IC, PSFM7 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LA7840 | 制造商:Panasonic Industrial Company 功能描述:IC |
| LA7840_06 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Vertical Output IC |
| LA7841 | 制造商:SANYO Semiconductor Co Ltd 功能描述: |
| LA7841_0609 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Vertical Output IC |
| LA7845 | 制造商:Panasonic Industrial Company 功能描述:SUB ONLY IC |
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