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NTE1549 Integrated Circuit Dot/Bar Display Driver
Description: The NTE1549 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs, LCDs, or vacuum fluorescent displays, providing an electronic version of the popular VU meter. 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 resistors. The whole display system can operate from a single supply as low 3V or as high as 25V. This IC contains an adjustable voltage reference and an accurate ten-step voltage divider. The high impedance input buffer accepts signals down to ground and up to within 1.5V of the positive supply. Further, it needs no protection against inputs of 35V. The input buffer drives 10 individual comparators referenced to the precision divider. Accuracy is typically better than 0.2dB. Audio applications include average or peak level indicators, and power meters. Replacing conventional meters with an LED bar graph results in a faster responding, more rugged display with high visibility that retains the ease of interpretation of an analog display. The NTE1549 is extremely easy to apply. A 12V full-scale meter requires only one resistor in addition to the ten LEDs. One more resistor program in addition to the full-scale anywhere from 1.2V to 12V independent of supply voltage. LED brightness is easily controlled with a single pot. The NTE1549 is very versatile. The outputs can drive LCDs, vacuum fluorescents and incandescent bulb as well as LEDs of any color. Multiple devices can be cascaded for a dot or bar mode display for increased range and/or resolution. Features: D Fast responding electronic VU meter D Drives LEDs, LCDs, or vacuum fluorescents D Bar or dot display mode externally selectable by user D Expandable to displays of 70dB D Internal voltage reference from 1.2V to 12V D Operates with a single supply of 3V to 25V D Inputs operate down to ground D Output current programmable from 1mA to 30mA D Input withstands 35V without damabe or false outputs D Outputs are current regulated, open collectors D Directly drives TTL or CMOS D The internal 10-step divider is floating and can be referenced to a wide range of voltages.
Absolute Maximum Ratings: Power Dissipation (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625mW Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25V Voltage on Output Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25V Input Signal Overvoltage (Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35V Divider Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -100mV to V+ Reference Load Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to +150C Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300C Note 1. The maximum junction temperature of the NTE1549 is 100C. Devices must be derated for operation at elevated temperatures. Junction to ambient thermal resistance is 120C/W. Note 2. Pin 5 input current must be limited to 3mA. The addition of a 39k resistor in series with Pin5 allows 100V signals without damage. Electrical Characteristics: (Note 3)
Parameter Comparators Offset Voltage, Buffer and First Comparator Offset Voltage, Buffer and Any Other Comparator Gain (ILED/VIN) Input Bias Current (At Pin5) Input Signal Overvoltage Voltage Divider Divider Resistance Relative Accuracy (Input Change Between Any Two Threshold Points) Total Pin6 to Pin4 -1dB VIN 3dB, Note 4 -7dB VIN -1dB, Note 4 -10dB VIN -7dB, Note 4 Absolute Accuracy VIN = 2, 1, 0, -1dB VIN = -3, -5dB VIN = -7, -10, -20dB Voltage Reference Output Voltage Line Regulation Load Regulation Output Voltage Change with Temperature Adjust Pin Current 0.1mA IL(REF) 4mA, V+ = VLED = 5V 3V V+ 18V 0.1mA IL(REF) 4mA, V+ = VLED = 5V 0 TA +70C, IL(REF) = 1mA, V+ = VLED = 5V 1.2 - - - - 1.28 0.01 0.4 1 75 1.34 0.03 2.0 - 120 V %/V % % mA 8 0.75 1.5 2.5 -0.25 -0.5 -1 12 1.0 2.0 3.0 - - - 17 1.25 2.5 2.5 +0.25 +0.5 +1 k dB dB dB dB dB dB 0V VRLO = VRHI 12V, ILED = 1mA 0V VRLO = VRHI 12V, ILED = 1mA I(REF) = 2mA, ILED = 10mA 0V VIN (V+ =1.5V) No Change in Display - - 3 - -35 3 3 8 25 - 10 15 - 100 +35 mV mV mA/mV nA V Test Conditions Min Typ Max Unit
Note 3. Unless otherwise stated, all specifications apply with the following conditions: 3VDC V+ 20VDC; -0.015V VRLO 12VDC; TA = +25C, IL(REF) = 0.2mA, Pin9 connected to Pin3 bar mode. 3VDC VLED V+; VREF, VRHI, VRLO (V+ -1.5V); For higher power dissipations, pulse testing is used. -0.015V VRHI 12VDC; 0V VIN V+ -1.5V Note 4. Accuracy is measured referred to +3dB = +3dB = +10.000VDC at Pin5, with +10.000VDC at Pin6, and 0.000 VDC at Pin4. At lower full-scale voltages, buffer and comparator offset voltage may add significant error.
Electrical Characteristics (Cont'd): (Note 3)
Parameter Output Drivers LED Current LED Current Difference (Between Largest and Smallest LED Currents) LED Current Regulation V+ = VLED = 5V, IL(REF) = 1mA VLED = 5V, ILED = 2mA VLED = 5V, ILED = 20mA 2V VLED 17V, ILED = 2mA 2V VLED 17V, ILED = 20mA Dropout Voltage Saturation Voltage Output Leakage, Each Collector Output Leakage, Pin10 through Pin18 Output Leakage, Pin1 Supply Current Standby Supply Current (All Outputs Off) V+ = +5V, IL(REF) = 0.2mA V+ = +20V, IL(REF) = 1mA - - 2.4 6.1 4.2 9.2 mA mA ILED(ON) = 20mA @ VLED = 0.4mA, ILED = 2mA ILED = 2mA, IL(REF) = 0.4mA Bar Mode, Note 5 Dot Mode, Note 5 7 - - - - - - - - 60 10 0.12 1.2 0.1 1.0 - 0.15 0.1 0.1 150 13 0.4 3.0 0.25 3.0 1.5 0.4 100 100 450 mA mA mA mA mA V V A A A Test Conditions Min Typ Max Unit
Note 3. Unless otherwise stated, all specifications apply with the following conditions: 3VDC V+ 20VDC; -0.015V VRLO 12VDC; TA = +25C, IL(REF) = 0.2mA, Pin9 connected to Pin3 bar mode. 3VDC VLED V+; VREF, VRHI, VRLO (V+ -1.5V); For higher power dissipations, pulse testing is used. -0.015V VRHI 12VDC; 0V VIN V+ -1.5V Note 5. Bar mode results when Pin9 is within 20mV of V+. Dot mode results when Pin9 is pulled at least 200mV below V+. LED #10 (Pin10 output current) is disabled if Pin9 is pulled 0.9V or more below VLED. Threshold Voltage: (Note 4)
dB 3 2 1/4 1 1/4 0 1/4 -1 1/2 Volts Min 9.985 8.660 7.718 6.879 5.957 Typ 10.000 8.913 7.943 7.079 6.310 Max 10.015 9.173 8.175 7.286 6.683 dB -3 1/2 -5 1/2 -7 1 -10 1 -20 1 Volts Min 4.732 3.548 2.818 1.995 0.631 Typ 5.012 3.981 3.162 2.239 0.708 Max 5.309 4.467 3.548 2.512 0.794
Note 4. Accuracy is measured referred to +3dB = +3dB = +10.000VDC at Pin5, with +10.000VDC at Pin6, and 0.000 VDC at Pin4. At lower full-scale voltages, buffer and comparator offset voltage may add significant error.
Pin Connection Diagram
LED1 1 V (-) 2 V (+) 3 Divider (Low End) 4 Signal 5 Divider (High End) 6 Reference Output 7 Reference Adjust 8 Mode Select 9
18 LED2 17 LED3 16 LED4 15 LED5 14 LED6 13 LED7 12 LED8 11 LED9 10 LED10
18
10
1
9
.870 (22.1) Max
.250 (6.35)
.150 (3.8)
.100 (2.54) .800 (20.3)
.125 (3.17) Min

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