1 of 9 102899 features 128 position, digitally controlled poten- tiometer operates from a +5 volts power supply with ttl signal inputs wide analog voltage range of 5 volts low-power cmos 14-pin dip or 16-pin soic for surface mount applications default position on power up sets wiper position to 10% of active digital taps (3% of the total end-to-end resistance) operating temperature range C industrial temp. range: -40c to +85c resistance/step resistance values low end high end -3db point DS1666-10 10k 24 ? 152 ? 1.0 mhz ds1666-50 50k 122 ? 759 ? 200 khz DS1666-100 100k 243 ? 1.519 ? 100 khz pin assignment pin descriptions v h - high terminal of potentiometer v l - low terminal of potentiometer v w - wiper terminal of potentiometer u/ d - up/down control inc - wiper movement control cs - chip select for wiper movement nc - no connection v cc - 5v power supply input gnd - ground v b - substrate bias voltage (0 to -5v) description the ds1666 audio digital resistor is a solid-state potentiometer composed of 127 digitally controlled resistive elements. between each resistive section and both ends of the potentiometer are tap points multiplexed to the wiper. the position of the wiper on the resistance array is controlled by the cs , u/ d and inc inputs. the taper of the ds1666 is shown in figure 1. ds1666 audio digital resisto r www.dalsemi.com nc u/d inc cs gnd ncnc 1413 12 11 10 98 ncv cc v b v w v h v l nc 12 3 4 5 6 7 14-pin dip (300 mil) see mech. drawings section 16-pin soic (300 mil) see mech. drawings section u/d 1 16 v cc ncnc inc nc cs nc gnd 23 4 5 6 7 8 1514 13 12 11 10 9 v b v w v h ncv l ncnc downloaded from: http:///
ds1666 2 of 9 102899 the ds1666 is uniquely designed to provide a potentiometer that is pseudo-logarithmic rather than linear across its entire range. the lower half of the potentiometer advances 1% of total resistance for each 3% of scale advanced, providing for precise amplification of low volume signals. the upper half of the potentiometer advances 2% of resistance for every 1% of scale advanced, providing for the lower resolution gain required for high volume amplification. graph of audio taper figure 1 operation the ds1666 has a total of 128 tap-points including the v l and v h terminals. a total of 127 resistive segments exist between the v l and v h terminals. these tap-points are accessible to the v w terminal whose position is controlled via a 3-terminal control port. a block diagram of the ds1666 is shown in figure 2. the 3-terminal port of the ds1666 provides an increment/ decrement interface which is activated via a chip select input. this interface consists of the input signals cs , inc , and u/ d . these input signals control a 7-bit up/down counter. the output of the 7-bit up/down counter controls a 1 of 128 decoder to select wiper position. the timing diagram for the 3-terminal interface control is shown in figure 4. analog characteristics the ds1666 has a pseudo-logarithmic resistor array that resembles an audio taper potentiometer as shown in figure 1. taps on the lower portion of the potentiometer increment 0.25% of the total resistance and are specified to within 0.5% of the expected value. taps on the higher portion increment 1.5% of the total resistance and are specified to within 2.0% of the expected value. end-to-end resistance tolerance = 20 % temperature coefficient = 750 ppm/c typical downloaded from: http:///
ds1666 3 of 9 102899 pin descriptions v cc - power supply. the ds1666 will support supply voltages ranging from +4.5 to +5.5 volts. gnd - ground terminal. v b - negative bias. the ds1666 will support a negative bias ranging from 0 to -5 volts. h - high-terminal of potentiometer. it is not required that this terminal be connected to a potential greater than the v l terminal. voltage applied to the v h terminal can not exceed the power-supply voltage, (v cc ), or go below the negative bias, (v b ). v l - low-terminal of potentiometer. it is not required that this terminal be connected to a potential less than the v h terminal. voltage applied to the v l terminal cannot exceed the power-supply voltage, (v cc ), or go below the negative bias (v b ). v w - wiper of the potentiometer. its position on the resistor array is controlled by the 3-terminal control port. voltage applied to the wiper cannot exceed the power-supply voltage, v cc , or go below the negative bias (v b ). cs - chip select. the cs input is used to activate the control port of the ds1666. this input is active low. when in a high-state, activity on the inc and u/ d port pins will not affect or change wiper position. inc - wiper movement control. this input provides for wiper position changes when the cs pin is low. wiper position changes will occur one position per high-to-low transition of this input signal. position changes will not occur if the cs pin is in a high-state. u/ d - up/down control. this input sets the direction of wiper movement. when in a high-state and cs is low, any high-to-low transition on inc will cause a one position movement of the wiper towards the v h terminal. when in a low-state and cs is low, any high-to-low transitions on inc will cause the position of the wiper to move towards the v l terminal. downloaded from: http:///
ds1666 4 of 9 102899 block diagram figure 2 mode selection figure 3 downloaded from: http:///
ds1666 5 of 9 102899 absolute maximum ratings* voltage on cs , inc , u/ d and u/ d and v cc relative to ground -0.5v to +7.0v voltage on v h , v l and v w relative to ground -6.5v to +6.5v voltage on v b -6.5v to gnd operating temperature -40 to +85c storage temperature -55c to +125c soldering temperature 260c for 10 seconds * this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. recommended dc operating conditions (-40 c to +85 c) parameter symbol min typ max units notes supply voltage v cc +4.5 5.0 5.5 v 1 input logic 1 v ih 2.0 v cc +0.5 v 1 input logic 0 v il -0.5 +0.8 v 1 v h , v l , v w voltage v r v b -0.3 v cc +0.3 v 1, 3 v b voltage v b -5.5 gnd v 1 dc electrical characteristics (-40 c to +85 c; v cc = 5.0v 10%) parameter symbol min typ max units notes supply current i cc 0.2 4.5 ma 4 input leakage i li -1 +1 a wiper resistance r w 350 900 2 wiper current i w 1m a capacitance (t a =25 c) parameter symbol condition typ max units notes capacitance c in t a =25 c 6p f downloaded from: http:///
ds1666 6 of 9 102899 analog resistor characteristics (-40 c to +85 c; v cc = 5.0v 10%) parameter symbol min typ max units notes total resistance -10-50 -100 1050 100 k k k 55 5 end-to-end resistor tolerance -20 +20 % 8 absolute tolerance low end (0.25% increments) high end (1.5% increments) -0.5-2.0 +0.5+2.0 %% 66 -3 db cutoff frequency f cutoff mhz 7 temperature coefficient 750 ppm/ c ac electrical characteristics (-40 c to +85 c; v cc = 5.0v 10%) parameter symbol min typ max units notes cs to inc setup t ci 100 ns inc high to u/ d change t id 100 ns u/ d to inc setup t di 1 s inc low period t il 500 ns inc high period t ih 1 s inc low to wiper change t iw 200 ns downloaded from: http:///
ds1666 7 of 9 102899 ac timing figure 4 notes:1. all voltages are referenced to ground. 2. typical values are for t a =25c and nominal supply voltages. 3. resistors input voltages cannot go below v b or exceed v cc by the amounts shown. 4. maximum current specifications are based on the clock rate of inc input. this specification represents the current required when changing the wiper position. 5. the ds1666 is available in three end-to-end resistor values. these include 10k for the DS1666-10; 50k for the ds1666-50; and 100k for the DS1666-100. 6. absolute tolerance is used to compare measured wiper voltage versus expected wiper voltage as determined by wiper position. 7. -3db cutoff frequency characteristics for the ds1666 depend on potentiometer total resistance. the DS1666-10 is 1 mhz; the ds1666-50 is 200 khz; and the DS1666-100 is 100 khz. 8. valid at 25 c only ac test conditions input pulse levels 0v to 3v input rise and fall times 10 ns downloaded from: http:///
ds1666 8 of 9 102899 ds1666 ordering information ordering number package operating temperature version ds1666-010 14l dip -40c to +85c 10 k ds1666-050 14l dip -40c to +85c 50 k DS1666-100 14l dip -40c to +85c 100 k ds1666s-010* 16l soic (300-mil) -40c to +85c 10 k ds1666s-050* 16l soic (300-mil) -40c to +85c 50 k ds1666s-100* 16l soic (300-mil) -40c to +85c 100 k * add /t & r for tape and reel packaging. downloaded from: http:///
ds1666 9 of 9 102899 data sheet revision summary the following represent the key differences between 07/26/93 and 06/18/97 version of the ds1666 data sheet. please review this summary carefully. 1. remove commercial temp grade reference. 2. add order info table. 3. improve operating description and add analog resistor characteristics. downloaded from: http:///
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