Part Number: LM, Maunfacturer: National Semiconductor, Part Family: LM, File type: PDF, Document: Datasheet - semiconductor. Dot/Bar Display Driver, LM datasheet, LM circuit, LM data sheet: NSC, alldatasheet, datasheet, Datasheet search site for Electronic Components. LM Dot/Bar Display Driver. General Description. The LM is a monolithic integrated The LM is very easy to apply as an analog meter circuit.
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The LM is rated for operation from 0°C to +70°C. Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. The LM is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing LM Dot/Bar Display Driver datasheet (Rev. LM is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph. Current drive to the LEDs is regulated and programmable, eliminating the need for.
Based on the responses, I have two solutions for blanking the LM I think the first method gets close to making sense of the datasheet in my original question. The second method illustrates a technique to "gate off" the input signal, also per the datasheet. I tested both of these solutions on the bench and they seem to work fine. Note: The LM provides 1. In the following schematics, the internal voltage reference of 1.
No multiplex switching or interaction between outputs. The LM is very easy to apply as an analog meter circuit. Input withstands?
LED driver outputs are current regulated,. If the 1. When in the dot mode, there is a small amount of overlap or. This assures that at. Various novel displays are possible. Typical Applications. Grounding method is typical of all uses.
The 2. F tantalum or 10?
F aluminum electrolytic capacitor is needed if leads to the LED supply are 6" or. Absolute Maximum Ratings Note 1. Storage Temperature Range. Soldering Information. Dual-In-Line Package. Distributors for availability and specifications. Soldering 10 seconds.
Plastic Chip Carrier Package. Power Dissipation Note 6. Vapor Phase 60 seconds. Molded DIP N. Infrared 15 seconds. Supply Voltage. Voltage on Output Drivers. Input Signal Overvoltage Note 4. Divider Voltage. Reference Load Current. Electrical Characteristics Notes 2, 4. Conditions Note 2. Offset Voltage, Buffer and First.
Offset Voltage, Buffer and Any Other. Input Bias Current at Pin 5. Input Signal Overvoltage. No Change in Display. Divider Resistance.
Total, Pin 6 to 4.
Note 3. Output Voltage. Line Regulation. Load Regulation. Output Voltage Change with. Adjust Pin Current. LED Current. LED Current Regulation. Dropout Voltage. Saturation Voltage. Output Leakage, Each Collector. Bar Mode Note 5. Output Leakage. Dot Mode Note 5. Pins 10? Pin 1.
Standby Supply Current. All Outputs Off. Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which. This assumes that the device is within the Operating Ratings.
Specifications are not guaranteed for parameters where no limit. Note 2: Unless otherwise stated, all specifications apply with the following conditions: For higher power dissipations, pulse testing is used. Note 3: At lower full-scale voltages, buffer and comparator offset voltage may add. Note 4: Pin 5 input current must be limited to? The addition of a 39k resistor in series with pin 5 allows? Note 5: LED No.
Note 6: The maximum junction temperature of the LM is ? Devices must be derated for operation at elevated temperatures. Junction to ambient thermal. LED Current Regulation: The change in output current. Definition of Terms. The difference between the observed threshold. As the forward. Specified and tested with 10V across the internal voltage. Line Regulation: The average change in reference output.
Adjust Pin Current: Current flowing out of the reference. Load Regulation: The change in reference output voltage. Comparator Gain: The ratio of the change in output current. Offset Voltage: The differential input voltage which must be. Dropout Voltage: The voltage measured at the current.
Most significant error when the voltage across the. Specified and tested with pin. Input Bias Current: Current flowing out of the signal input. Typical Performance Characteristics. Supply Current vs. Operating Input Bias. Current vs Temperature. Reference Voltage vs. Reference Adjust Pin. LED Current-Regulation. LED Driver Saturation. Input Current Beyond. The current drawn out of the reference voltage pin pin 7 determines LED current. Approximately 10 times this current will be drawn through each lighted LED, and this current will be relatively constant despite supply voltage and temperature changes.
Current drawn by the internal resistor divider, as well as by the external current and voltage-setting divider should be included in calculating LED drive current. The ability to modulate LED brightness with time, or in proportion to input voltage and other signals can lead to a number of novel displays or ways of indicating input overvoltages, alarms, etc.
The following tabulation shows the basic ways of using this input. Other more complex uses will be illustrated in the applications. Continue connecting pin 9 of lower input drivers to pin 1 of higher input drivers for 30, 40, or more LED displays. The last LM driver in the chain will have pin 9 wired to pin All previous drivers should have a 20k resistor in parallel with LED No.
In this case, for each mV that the input signal increases, a comparator will switch on another indicating LED. This resistor divider can be connected between any 2 voltages, providing that they are 1.
If an expanded scale meter display is desired, the total divider voltage can be as little as mV. Expanded-scale meter displays are more accurate and the segments light uniformly only if bar mode is used. At 50 mV or more per step, dot mode is usable.
One pin changes the display from a bar graph to a moving dot display. LED current drive is regulated and programmable, eliminating the need for current limiting re-sistors. The whole display system can operate from a single supply as low as 3V or as high as 25V.
Multiple devices can be cascaded for a dot or bar mode display with a range of 60 or 90 dB. Google Custom Search Got a question on this topic?
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