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參數資料
| 型號： | LM3914N-1 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 顯示驅動器 |
| 英文描述： | MULTI DVI TRANSMITTER -FIBER |
| 中文描述： | LED DISPLAY DRIVER, PDIP18 |
| 封裝： | PLASTIC, DIP-18 |
| 文件頁數： | 15/19頁 |
| 文件大小： | 365K |
| 代理商： | LM3914N-1 |
Application Hints
(Continued)
APPLICATION TIPS FOR THE LM3914 ADJUSTABLE
REFERENCE
GREATLY EXPANDED SCALE (BAR MODE ONLY)
Placing the LM3914 internal resistor divider in parallel with a
section (
230
) of a stable, low resistance divider greatly
reduces voltage changes due to IC resistor value changes
with temperature. Voltage V
should be trimmed to 1.1V first
by use of R2. Then the voltage V
across the IC divider string
can be adjusted to 200 mV, using R5 without affecting V
1
.
LED current will be approximately 10 mA.
NON-INTERACTING ADJUSTMENTS FOR EXPANDED
SCALE METER (4.5V to 5V, Bar or Dot Mode)
This arrangement allows independent adjustment of LED
brightness regardless of meter span and zero adjustments.
First, V
is adjusted to 5V, using R2. Then the span (voltage
across R4) can be adjusted to exactly 0.5V using R6 without
affecting the previous adjustment.
R9 programs LED currents within a range of 2.2 mAto 20 mA
after the above settings are made.
ADJUSTING LINEARITY OF SEVERAL STACKED
DIVIDERS
Three internal voltage dividers are shown connected in se-
ries to provide a 30-step display. If the resulting analog meter
is to be accurate and linear the voltage on each divider must
be adjusted, preferably without affecting any other adjust-
ments. To do this, adjust R2 first, so that the voltage across
R5 is exactly 1V. Then the voltages across R3 and R4 can
be independently adjusted by shunting each with selected
resistors of 6 k
or higher resistance. This is possible be-
cause the reference of LM3914 No. 3 is acting as a constant
current source.
The references associated with LM3914s No. 1 and No. 2
should have their Ref Adj pins (pin 8) wired to ground, and
their Ref Outputs loaded by a 620
resistor to ground. This
makes available similar 20 mA current outputs to all the
LEDs in the system.
If an independent LED brightness control is desired (as in
the previous application), a unity gain buffer, such as the
LM310, should be placed between pin 7 and R1, similar to
the previous application.
Greatly Expanded Scale (Bar Mode Only)
DS007970-15
L
www.national.com
15
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM3914N-1 | 制造商:Texas Instruments 功能描述:LED BAR GRAPH DRIVER 3914 DIP18 |
| LM3914N-1/HALF | 制造商:Texas Instruments 功能描述:LED BAR GRAPH DRIVER 3914 DIP18 |
| LM3914N-1/NOPB | 功能描述:LED照明驅動器 DOT/BAR DISPLAY DRVR 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 |
| LM3914N-1/NOPB | 制造商:Texas Instruments 功能描述:LED Driver IC |
| LM3914V | 功能描述:LED照明驅動器 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 |
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