NTE1509 Integrated Circuit 10–Step Dot/Bar Display Driver for Logarithmic Scale Description: The NTE1509 is a monolithic integrated circuit in an 18–Lead DIP type package that senses analog voltage levels and drives 10 LEDs, LCDs, or vacuum fluorescent displays, providing a logarithmic 3dB analog display. A single pin changes the display from a bar graph to a moving dot display. LED current is regulated and programmable, eliminating the need for current limiting resistors. The whole display system can operate from a single supply as low as 3V or as high as 25V The circuit contains its own adjustable reference and accurate 10–step voltage divider. The high impedance input buffer accepts signals down to GND 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 1dB. The NTE1509’s 3dB/step display is suited for signals with wide dynamic range, such as audio level, power, light intensity, or vibration. Audio applications include average or peak level indicators, power meters, and RF signal strength 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 NTE1509 is extremely easy to apply. A 1.2V full–scale meter requires only 1 resistor in addition to the 10 display LEDs. One more resistor programs the full–scale anywhere from 1.2V to 12V independent of supply voltage. LED brightness is easily controlled with a single pot. The NTE1509 is very versitile. The outputs can drive LCDs, vacuum fluorescents, and incandescent bulbs as well as LEDs of any color. Multiple devices can be cascaded for a dot or bar mode display with a range of 60 or 90dB. NTE1509s can also be cascaded with NTE1508s for a linear/log display or with NTE1549s for an extended–range VU meter. Features: D 3dB/Step, 30dB Range D D Drives LEDs, LCDs or vacuum fluorescents D D Bar or dot display mode externally selectable by user D D Expandable to displays of 90dB D Internal voltage reference from 1.2V to 12V D D Operates with single supply of 3V to 25V D D Inputs operate down to GND Output current programmable from 1 to 30mA Input withstands ±35V without damage or false outputs Outputs are current regulated, open–collectors Directly Drives TTL or CMOS The internal 10–step divider is floating and can be referenced to a wide range of voltages Absolute Maximum Ratings: Power Dissipation (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1365mW 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 +150°C Lead Temperature (During soldering, 10sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +260°C Note 1. The maximum junction temperature of the NTE1509 is +100°C. Device must be derated for operation at elevated temperatures. Junction to ambient thermal resistance is 55°C/W. Note 2. Pin5 input current must be limited to ±3mA. The addition of a 39kΩ resistor in series with Pin5 allows ±100V signals without damage. Electrical Characteristics: (Note 2, unless otherwise specified, all specifications apply with the following conditions: 3VDC ≤ V+ ≤ 20VDC VREF, VRHI, VRLO ≤ (V+ –1.5V) 3VDC ≤ VLED ≤ V+ 0V ≤ VIN ≤ V+ –1.5V –0.015V ≤ VRLO ≤ 12VDC TA +25°C, IL(REF) = 0.2mA, –0.015V ≤ VRHI ≤ 12VDC Pin9 connected to Pin3 (Bar Mode) Parameter Test Conditions Min Typ Max Unit Comparator Offset Voltage, Buffer, and First Comparator 0V ≤ VRLO = VRHI ≤ 12V, ILED = 1mA – 3 10 mV Offset Voltage, Buffer, and Any Other Comparator 0V ≤ VRLO = VRHI ≤ 12V, ILED = 1mA – 3 15 mV Gain (∆ILED/∆VIN) IL(REF) = 2mA, ILED = 10mA 3 8 – mA/mV Input Bias Current (At Pin5) 0V ≤ VIN ≤ V+ =1.5V – 25 100 nA Input Signal Overdrive No Change is Display –35 – +35 V Divider Resistance Total, Pin6 to Pin4 16 28 36 kΩ Relative Accuracy (Input Change Between Any Two Threshold Points) Note 3 2.0 3.0 4.0 dB Absolute Accuracy at Each Threshold Point VIN = –3, –6dB, Note 3 –0.5 – +0.5 dB VIN = –9dB, Note 3 –0.5 – +0.65 dB VIN = –12, –15, –18dB, Note 3 –0.5 – +1.0 dB VIN = –21, –24, –27dB, Note 3 –0.5 – +1.5 dB Output Voltage 0.1mA ≤ IL(REF) ≤ 4mA, V+ = VLED = 5V 1.2 1.28 1.34 V Line Regulation 3V ≤ V+ ≤ 18V – 0.01 0.03 %/V Load Regulation 0.1mA ≤ IL(REF) ≤ 4mA, V+ = VLED = 5V – 0.4 2.0 % Output Voltage Change with Temperature 0° ≤ TA ≤ +70°C, IL(REF) = 1mA, V+ = 5V – 1 – % – 75 120 µA Voltage Divider Voltage Reference Adjust Pin Current Note 2. Pin5 input current must be limited to ±3mA. The addition of a 39kΩ resistor in series with Pin5 allows ±100V signals without damage. Note 3. Accuracy is measured referred to +10.000VDC at Pin5, with + 10.000VDC at Pin6, and 0.000VDC at Pin4. At lower full–scale voltages, buffer and comparator offset voltage may add significant error. See table for threshold voltages. Electrical Characteristics (Cont’d): (Note 2, unless otherwise specified, all specifications apply with the following conditions: 3VDC ≤ V+ ≤ 20VDC VREF, VRHI, VRLO ≤ (V+ –1.5V) 3VDC ≤ VLED ≤ V+ 0V ≤ VIN ≤ V+ –1.5V –0.015V ≤ VRLO ≤ 12VDC TA +25°C, IL(REF) = 0.2mA, –0.015V ≤ VRHI ≤ 12VDC VLED = 3V, Pin9 connected to Pin3 (Bar Mode) Parameter Test Conditions Min Typ Max Unit 7 10 13 mA ILED = 2mA – 0.12 0.4 mA ILED = 20mA – 1.2 3.0 mA ILED = 2mA – 0.1 0.25 mA ILED = 20mA – 1 3 mA Output Drivers LED Current V+ = VLED = 5V, IL(REF) = 1mA LED Current Difference (Between Largest and Smallest LED Currents) VLED = 5V LED Current Regulation 2V ≤ VLED ≤ 17V Dropout Voltage ILED(ON) = 20mA, VLED = 5V, ∆ILED = 2mA – – 1.5 V Saturation Voltage ILED = 2mA, IL(REF) = 0.4mA – 0.15 0.4 V Output Leakage, Each Collector Bar Mode, Note 4 – 0.1 10 µA Output Leakage Dot Mode, Note 4 Pin10 to Pin18 – 0.1 10 µA Pin1 60 150 450 µA V+ = 5V, IL(REF) = 0.2mA – 2.4 4.2 µA V+ = 20V, IL(REF) = 1mA – 6.1 9.2 µA Supply Current Standby Supply Current (All Outputs OFF) Note 2. Pin5 input current must be limited to ±3mA. The addition of a 39kΩ resistor in series with Pin5 allows ±100V signals without damage. Note 4. Bar mode results when Pin9 is within 20mV of V+. Dot mode results when Pin9 is pulled at least 200mV below V+ or left open circuit. LED No. 10 (Pin10 output current) is disabled if Pin9 is pulled 0.9V or more below VLED. Threshold Voltage: (Note 3) Output dB Min Typ Max 1 –27 0.422 0.447 0.531 1 –24 0.596 0.631 3 –21 0.841 4 –18 5 –15 Output dB Min Typ Max 6 –12 2.372 2.512 2.819 0.750 7 –9 3.350 3.548 3.825 0.891 1.059 8 –6 4.732 5.012 5.309 1.189 1.259 1.413 9 –3 6.683 7.079 7.498 1.679 1.778 1.995 10 0 9.985 10.000 10.015 Note 3. Accuracy is measured referred to +10.000VDC at Pin5, with + 10.000VDC at Pin6, and 0.000VDC at Pin4. At lower full–scale voltages, buffer and comparator offset voltage may add significant error. See table for threshold voltages. Pin Connection Diagram LED1 1 18 LED2 V (–) 2 17 LED3 V (+) 3 16 LED4 Divider Low 4 15 LED5 Signal Input 5 14 LED6 Divider High 6 13 LED7 Reference Output 7 12 LED8 Reference Adjust 8 11 LED9 Mode 9 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