DS1802 Dual Audio Taper Potentiometer With Pushbutton Control www.dalsemi.com FEATURES PIN ASSIGNMENT Ultra-low power consumption Operates from 3V or 5V supplies GND 1 20 VCC Two digitally controlled, 65-position COUT 2 19 VU (UC1) potentiometers including mute CLK 3 18 VD (DC1) Logarithmic resistive characteristics (1 dB D 4 17 B0 (UC0) per step) RST 5 16 B1 (DC0) Zero-crossing detection eliminates noise caused by wiper movement ZCEN 6 15 MUTE Digital or mechanical pushbutton wiper MODE 7 14 AGND control W0 8 13 H1 Serial port provides means for setting and L0 9 12 L1 reading both potentiometers wipers H0 10 11 W1 20-pin SOIC and 20-pin TSSOP for surface mount applications 20-Pin DIP (300-mil) Operating Temperature Range: 20-Pin SOIC (300-mil) -40C to +85C 20-Pin TSSOP (173-mil) Software and hardware mute See Mech. Drawings Section Resistance Available: 45 k PIN DESCRIPTION L0, L1 - Low End of Resistor H0, H1 - High End of Resistor W1,W2 - Wiper End of Resistor V - 3V/5V Power Supply Input CC RST - Serial Port Reset Input D - Serial Port Data Input CLK - Serial Port Clock Input MODE - Mode Select Input UC0, UC1 - Up Control Pushbutton Inputs DC0, DC1 - Down Control Pushbutton Inputs VU, VD - Volume-Up/Volume-Down Inputs B0, B1 - Balance Pot-0, Pot-1 Inputs GND - Digital Ground MUTE - Mute AGND - Analog Ground ZCEN - Zero-Crossing Detect Input C - Cascade Output OUT 1 of 17 051401 DS1802 DESCRIPTION The DS1802 is a dual audio taper-potentiometer having logarithmic resistive characteristics over the device range. Each potentiometer provides 65 wiper positions with a 1 dB increment per step and device mute. The DS1802 has two methods of device control, which include contact closure (pushbutton) inputs and a 3-wire serial interface for wiper positioning. The pushbutton control inputs provide a simple interface for device control without the need for a CPU. While the 3-wire serial interface, using a CPU, provides the user the ability of reading or writing exact wiper positions of the two potentiometers. The DS1802 can also be configured to operate in either independent or stereo modes when using pushbutton control. Independent mode of operation allows for independent wiper control, and stereo mode of operation provides single input control over both potentiometer wiper positions. The DS1802 is offered in commercial temperature versions. Packages for the part include a 20-pin DIP, 20-pin SOIC, and 20-pin TSSOP. OPERATION The DS1802 provides two 65-position potentiometers per package, each having a logarithmic resistive characteristic as shown in Table 1. The DS1802 can be controlled either digitally or mechanically using a 3-wire serial interface or contact closure input, respectively. The pushbutton interface allows for a simple mechanical control method for incrementing or decrementing wiper position. The 3-wire serial interface is designed for CPU controlled applications and allows the potentiometers exact wiper position to be read or written. Additionally, the DS1802 can be daisy-chained for multi-device environments. Figure 1 presents a block diagram of the DS1802. As shown, the inputs from the 3-wire serial interface and contact closure inputs drive a command/control unit. The command/control unit interprets these inputs for control of the two potentiometers. The MODE input is used for contact closure operation. This input allows the user to choose between independent mode control and stereo mode control. The MODE input is discussed in detail under the contact closure interface control. On power-up the serial port is stable and active within 10 microseconds. The contact closure control interface inputs are active after 50 ms. The wiper position on power-up will be at position 63, the low end of the potentiometer. Position 64 is the mute level. RESISTANCE CHARACTERISTICS Table 1 POSITION OUTPUT LEVEL (dB) 0 0 1 -1 2 -2 3 -3 4 -4 5 -5 63 -63 64(mute) <-90 2 of 17