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参数资料
| 型号： | LM1882RJ/883 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 消费家电 |
| 英文描述： | SPECIALTY CONSUMER CIRCUIT, CDIP20 |
| 封装： | CERAMIC, DIP-20 |
| 文件页数： | 3/16页 |
| 文件大小： | 236K |
| 代理商： | LM1882RJ/883 |
AC Operating Requirements (Continued)
TLF10137 – 6
FIGURE 4 AC Specifications
Additional Applications Information
POWERING UP
The ’ACT715LM1882 default value for Bit 10 of the Status
Register is 0 This means that when the CLEAR pulse is
applied and the registers are initialized by loading the de-
fault values the CLOCK is disabled Before operation can
begin Bit 10 must be changed toa1to enable CLOCK If
the default values are needed (no other programming is re-
quired) then
Figure 5 illustrates a hardwired solution to facili-
tate the enabling of the CLOCK after power-up Should con-
trol signals be difficult to obtain
Figure 6 illustrates a possi-
ble solution to automatically enable the CLOCK upon pow-
er-up Use of the ’ACT715-RLM1882-R eliminates the
need for most of this circuitry Modifications of the
Figure 6
circuit can be made to obtain the lone CLEAR pulse still
needed upon power-up
Note that although during a Vectored Restart none of the
preprogrammed registers are affected some signals are af-
fected for the duration of one frame only These signals are
the Horizontal and Vertical Drive signals After a Vectored
Restart the beginning of these signals will occur at the first
CLK The end of the signals will occur as programmed At
the completion of the first frame the signals will resume to
their programmed start and end time
PREPROGRAMMING ‘‘ON-THE-FLY’’
Although the ’ACT715LM1882 and ’ACT715-RLM1882-R
are completely programmable certain limitations must be
set as to when and how the parts can be reprogrammed
Care must be taken when reprogramming any End Time
registers to a new value that is lower than the current value
Should the reprogramming occur when the counters are at a
count after the new value but before the old value then the
counters will continue to count up to 4096 before rolling
over
For this reason one of the following two precautions are
recommended when reprogramming ‘‘on-the-fly’’ The first
recommendation is to reprogram horizontal values during
the horizontal blank interval only andor vertical values dur-
ing the vertical blank interval only Since this would require
delicate timing requirements the second recommendation
may be more appropriate
The second recommendation is to program a Vectored Re-
start as the final step of reprogramming This will ensure
that all registers are set to the newly programmed values
and that all counters restart at the first CLK position This
will avoid overrunning the counter end times and will main-
tain the video integrity
TLF10137 – 10
FIGURE 5 Default RS170 Hardwire Configuration
11
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相关代理商/技术参数 |
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| LM1884 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:TV STEREO DECODER |
| LM1884N | 制造商:NSC 制造商全称:National Semiconductor 功能描述:TV STEREO DECODER |
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