NTE7072 Integrated Circuit Dual DC Controlled Potentiometer Circuit Description: The NTE7072 is a monolithic integrated circuit designed for use as a volume and tone control circuit in stereo amplifiers. This dual tandem potentiometer IC consists of two ganged pairs of electronic potentiometers with eight inputs connected via impedance converters, and the four outputs driving individual operational amplifiers. The setting of each electronic potentiometer pair is controlled by an individual DC control voltage. The potentiometers operate by current division between the arms of cross–coupled long–tailed pairs. The current division factor is determined by the level and polarity of the DC control voltage with respect to an externally available reference level of half the supply voltage. Since the electronic potentiometers are adjusted by a DC control voltage, each pair can be controlled by single linear potentiometers which can be located in any position dictated by the equipment styling. Since the input and feedback impedances around the operational amplifier gain blocks are external, the NTE7072 can perform bass/treble and volume/loudness control. It also can be used as a low–level fader to control the sound distribution between the front and rear loudspeakers in car radio installations. Features: D High impedance inputs to both ‘ends’ of each electronic potentiometer D Ganged potentiometers track within 0.5dB D Electronic rejection of supply ripple D Internally–generated reference level available externally so that the control voltage can be made to swing positively and negatively around a well–defined 0V level D The operational amplifiers have push–pull outputs for wide voltage swing and low current consumption D The operation amplifier outputs are current limited to provide output short–circuit protection D Although designed to operate from a 20V supply (giving a maximum input and output signal level of 6V), the NTE7072 can work from a supply as low as 7.5V with reduced input and output signal levels Applications: D Volume Control D Tone Control D Low Level Fader Absolute Maximum Ratings: Supply Voltage (Pin11), VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23V Control Voltages (Pin9 and Pin10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1V Input Voltage Ranges at Pin3, Pin4, Pin5, Pin6, Pin13, Pin14, Pin15, and Pin16, VI (With respect to Pin18) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VCC Total Power Dissipation, PTOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800mW Thermal Resistance, Crystal–to–Ambient, RthCRA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80°C/W Operating Ambient Temperature Range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –30° to +80°C Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65° to +150°C Electrical Characteristics (Treble and Bass Control Circuit): (TA = +25°C, VCC = 20V, RG = 60Ω, RL > 4.7kΩ, CL < 30pF, f = 1kHz, with a linear frequency response (VC1 = VC2 = 0V), unless otherwise specified) Parameter Min Typ Max Unit Without load 14 22 30 mA VC1 = VC2 = 0V 10 – 20k Hz at linear frequency response (VC1 = VC2 = 0V) – 0 – dB f = 1kHz, at maximum bass/treble boost or cut at ±VC1 = ±VC2 = 120mV – ±1 – dB Bass Boost at 40Hz (ref. 1kHz) VC2 = 120mV – 17.5 – dB Bass Cut at 40Hz (ref. 1kHz) –VC2 = 120mV – 17.5 – dB Treble Boost at 16kHz (ref. 1kHz) VC1 = 120mV – 16 – dB Treble Cut at 16kHz (ref. 1kHz) –VC1 = 120mV – 16 – dB VO(RMS) = 300mV f = 1kHz (measured selectively) – 0.002 – % f = 20Hz to 20kHz – 0.005 – % f = 1kHz – 0.015 0.1 % f = 20Hz to 20kHz – 0.05 0.1 % 5.5 6.2 – V at reference level VO(RMS) = 5V (–3dB), THD = 0.1% – 40 – kHz signal plus noise (RMS) value, f = 20Hz to 20kHz – 75 – µV noise (peak value) weighted to DIN 45405, CCITT filter – 160 230 µV f = 1kHz – 86 – dB f = 20Hz to 20kHz – 80 – dB Supply Current Frequency Response (–1dB) Symbol ICC f Voltage Gain AV Gain Variation ∆AV Total Harmonic Distortion THD Test Conditions VO(RMS) = 5V Signal Level Power Bandwidth Output Noise Voltage VI, VO(RMS) THD = 0.7% (input and output) BW VNO(RMS) VNO(M) Crosstalk Attenuation (Stereo) ∝CT Control Voltage Crosstalk to the Outputs –∝CT f = 1kHz, VC1(RMS) = VC2(RMS) = 1mV – 20 – dB Ripple Rejection ∝100 f = 100Hz, VCC(RMS) < 200mV – 46 – dB Pin Connection Diagram Bypass 1 18 GND Output (2A) 2 17 Output (2B) Input (2A) 3 16 Input (2B) Input (2A) 4 15 Input (2B) Input (1A) 5 14 Input (1B) Input (1A) 6 13 Input (1B) Output (1A) 7 12 Output (1B) Reference Voltage 8 11 Control Voltage Input 9 10 Control Voltage Input 18 10 1 9 VCC .870 (22.1) Max .250 (6.35) .150 (3.8) .100 (2.54) .800 (20.3) .125 (3.17) Min