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參數(shù)資料
| 型號： | LM3915N |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 顯示驅(qū)動器 |
| 英文描述： | Dot/Bar Display Driver |
| 中文描述： | LED DISPLAY DRIVER, PDIP18 |
| 封裝： | PLASTIC, DIP-18 |
| 文件頁數(shù)： | 10/24頁 |
| 文件大小： | 602K |
| 代理商： | LM3915N |
Application Hints
(Continued)
CASCADING THE LM3915
To display signals of 60 dB or 90 dB dynamic range, multiple
LM3915s can be easily cascaded. Alternatively, it is possible
to cascade an LM3915 with LM3914s for a log/linear display
or with an LM3916 to get an extended range VU meter.
A simple, low cost approach to cascading two LM3915s is to
set the reference voltages of the two chips 30 dB apart as in
Figure 5 Potentiometer R1 is used to adjust the full scale
voltage of LM3915
#
1 to 316 mV nominally while the second
IC’s reference is set at 10V by R4. The drawback of this
method is that the threshold of LED
#
1 is only 14 mV and,
since the LM3915 can have an offset voltage as high as
10 mV, large errors can occur. This technique is not recom-
mended for 60 dB displays requiring good accuracy at the
first few display thresholds.
A better approach shown in Figure 6is to keep the reference
at 10V for both LM3915s and amplify the input signal to the
lower LM3915 by 30 dB. Since two 1% resistors can set the
amplifier gain within
±
0.2 dB, a gain trim is unnecessary.
However, an op amp offset voltage of 5 mV will shift the first
LED threshold as much as 4 dB, so that an offset trim may
be required. Note that a single adjustment can null out offset
in both the precision rectifier and the 30 dB gain stage. Alter-
natively, instead of amplifying, input signals of sufficient am-
plitude can be fed directly to the lower LM3915 and attenu-
ated by 30 dB to drive the second LM3915.
DS005104-11
D1, D2: 1N914 or 1N4148
FIGURE 3. Precision Full-Wave Average Detector
DS005104-12
D1, D2, D3, D4: 1N914 or 1N4148
FIGURE 4. Precision Full-Wave Peak Detector
L
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| LM3915 | Dot/Bar Display Driver |
| LM391N-100 | LM391 Audio Power Driver |
| LM3914VX | LED Display Driver |
| LM391 | LM391 Audio Power Driver |
| LM39301R-3.3 | 3A Low-Voltage Low-Dropout Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3915N/A+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LED Display Driver |
| LM3915N/B+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LED Display Driver |
| LM3915N-1 | 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM3915N-1 | 制造商:Texas Instruments 功能描述:LED BAR GRAPH DRIVER 3915 DIP18 |
| LM3915N-1/HALF | 制造商:Texas Instruments 功能描述:LED BAR GRAPH DRIVER 3915 DIP18 |
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