DS1866 Log Trimmer Potentiometer www.dalsemi.com FEATURES PIN ASSIGNMENT Single 8-position Log Trimmer Potentiometer P0 1 8 V CC 5-dB/step P1 2 7 P2 Operates from 2.7V to 5.5V supplies H 3 6 L Parallel interface control: P0, P1, P2 GND 4 5 W Standard Resistance Value: 10 k 8-pin DIPs 8-pin (150) SOICs 8-Pin DIP (300-mil) Operating Temperature Range: See Mech. Drawings Section - Industrial: -40C to +85C P0 1 8 V CC P1 2 7 P2 H 3 6 L GND 4 5 W 8-Pin SOIC (150-mil) See Mech. Drawings Section PIN DESCRIPTION H - High End of Resistor L - Low End of Resistor W - Wiper Terminal V - 3V or 5V Power Supply Input CC P0 - Position Select - Bit 0 P1 - Position Select - Bit 1 P2 - Position Select - Bit 2 GND - Ground DESCRIPTION The DS1866 Log Trimmer Potentiometer is a single volatile digital potentiometer having eight positions with a 5-dB resolution per step. The device provides an ideal method for low-cost trimming or volume control using a CPU or manual control input. The devices wiper position is set to one of eight positions by a 3-terminal parallel port. The value of the wiper position is determined by the P0, P1, and P2 port pins. The DS1866 is available as a 10k potentiometer and is available in an industrial temperature grade. Additionally, the DS1866 will operate from 3V or 5V supplies and is ideal for portable applications requiring low standby current. Two packaging options are available and include the 8-pin (300-mil) DIP, 8-pin (150-mil) SOIC. 1 of 5 102199DS1866 OPERATION The DS1866 is a single volatile potentiometer. The device has a total of eight positions providing a resolution of 5 dB per step and giving a total attenuation range of 0 dB to -35 dB. These tap points are accessible to the W-terminal whose position is controlled via a 3-terminal parallel port consisting of input signals P0, P1, and P2. A block diagram of the DS1866 is shown in Figure 1. Wiper position setting of the DS1866 is determined by the states of the P0, P1, and P2 input terminals. Table 1 below outlines position setting versus value of the parallel port inputs. A Position-0 setting places the wiper position at the L-terminal of the potentiometer and provides 35 dB of attenuation. As wiper position increases, attenuation decreases with Position-7 giving 0 dB of attenuation. On power-up, the wiper position of the DS1866 will be set to the P0, P1, and P2 values. P2 P1 P0 Wiper Attenuation (binary) Position (dB) 000 0 35 dB 001 1 30 dB 010 2 25 dB 011 3 20 dB 100 4 15 dB 101 5 10 dB 110 6 5 dB 111 7 0 dB PIN DESCRIPTIONS V - Power Supply Terminal. The DS1866 will support supply voltages ranging from +2.7 to +5.5 CC volts. GND - Ground Terminal. H - High-end Resistor. This is the high-end terminal of the potentiometer. It is not required that this terminal be connected to a potential greater than the L-terminal. Maximum voltage on the H-terminal can not exceed the power supply voltage, V , or go below ground. CC L - Low-end Resistor. This is the low-end terminal of the potentiometer. It is not required that this terminal be connected to a potential less than the H-terminal. Maximum voltage on the L-terminal can not exceed the power-supply voltage, V , or go below ground. CC W - Wiper of the Potentiometer. This pin is the wiper terminal of the potentiometer. Its position on the resistor array is controlled by the 3-terminal parallel port. Maximum voltage on the W-terminal can not exceed the power supply voltage, V , or go below ground. CC P0 - Bit 0. P0 is the bit 0 data input to the parallel port. P1 - Bit 1. P1 is the bit 1 data input to the parallel port. P2 - Bit 2. P2 is the bit 2 data input to the parallel port. 2 of 5 102199