APPLICATION NOTE A V A I L A B L E AN20 * AN42-53 * AN71 * AN73 * AN88 * AN91-92 * AN99 * AN115 * AN120 * AN124 * AN133 * AN134 * AN135 Terminal Voltage 0V to +15V, 100 Taps X9312 Digitally Controlled Potentiometer (XDCPTM) FEATURES DESCRIPTION * * * * The Xicor X9312 is a digitally controlled potentiometer (XDCP). The device consists of a resistor array, wiper switches, a control section, and nonvolatile memory. The wiper position is controlled by a 3-wire interface. * * * * * Solid-state potentiometer 3-wire serial interface Terminal voltage, 0 to +15V 100 wiper tap points --Wiper position stored in nonvolatile memory and recalled on power-up 99 resistive elements --Temperature compensated --End to end resistance range 20% Low power CMOS --VCC = 5V --Active current, 3mA max. --Standby current, 1mA max. High reliability --Endurance, 100,000 data changes per bit --Register data retention, 100 years RTOTAL values = 10K, 50K, and 100K Packages --8-lead SOIC and DIP The potentiometer is implemented by a resistor array composed of 99 resistive elements and a wiper switching network. Between each element and at either end are tap points accessible to the wiper terminal. The position of the wiper element is controlled by the CS, U/D, and INC inputs. The position of the wiper can be stored in nonvolatile memory and then be recalled upon a subsequent power-up operation. The device can be used as a three-terminal potentiometer or as a two-terminal variable resistor in a wide variety of applications including: - control - parameter adjustments - signal processing BLOCK DIAGRAM U/D INC CS VCC (Supply Voltage) 7-Bit Up/Down Counter Control and Memory Increment (INC) Device Select (CS) RW/VW 98 97 RH/VH Up/Down (U/D) RH/VH 99 7-Bit Nonvolatile Memory RL/VL 96 One of One Hundred Decoder Transfer Gates Resistor Array 2 VSS (Ground) General VCC VSS Store and Recall Control Circuitry 1 0 RL/VL RW/VW Detailed XDCP is a trademark of Xicor, Inc. REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 1 of 9 X9312 PIN DESCRIPTIONS PIN NAMES RH/VH and RL/VL The high (RH/VH) and low (RL/VL) terminals of the X9312 are equivalent to the fixed terminals of a mechanical potentiometer. The minimum voltage is 0V and the maximum is +15V. The terminology of RL/VL and RH/VH references the relative position of the terminal in relation to wiper movement direction selected by the U/D input and not the voltage potential on the terminal. RW/VW Rw/Vw is the wiper terminal and is equivalent to the movable terminal of a mechanical potentiometer. The position of the wiper within the array is determined by the control inputs. The wiper terminal series resistance is typically 40. Up/Down (U/D) The U/D input controls the direction of the wiper movement and whether the counter is incriminated or decremented. Increment (INC) The INC input is negative-edge triggered. Toggling INC will move the wiper and either increment or decrement the counter in the direction indicated by the logic level on the U/D input. Chip Select (CS) The device is selected when the CS input is LOW. The current counter value is stored in nonvolatile memory when CS is returned HIGH while the INC input is also HIGH. After the store operation is complete the X9312 will be placed in the low power standby mode until the device is selected once again. PIN CONFIGURATION DIP/SOIC INC 1 8 VCC U/D 2 7 CS RH/VH 3 6 RL/VL VSS 4 5 RW/VW REV 1.1.1 11/10/00 X9312 Symbol Description RH/VH High terminal RW/VW Wiper terminal RL/VL Low terminal VSS Ground VCC Supply voltage U/D Up/Down control input INC Increment control input CS Chip select control input PRINCIPLES OF OPERATION There are three sections of the X9312: the input control, counter and decode section; the nonvolatile memory; and the resistor array. The input control section operates just like an up/down counter. The output of this counter is decoded to turn on a single electronic switch connecting a point on the resistor array to the wiper output. Under the proper conditions the contents of the counter can be stored in nonvolatile memory and retained for future use. The resistor array is comprised of 99 individual resistors connected in series. At either end of the array and between each resistor is an electronic switch that transfers the potential at that point to the wiper. The wiper, when at either fixed terminal, acts like its mechanical equivalent and does not move beyond the last position. That is, the counter does not wrap around when clocked to either extreme. The electronic switches on the device operate in a "make before break" mode when the wiper changes tap positions. If the wiper is moved several positions, multiple taps are connected to the wiper for tIW (INC to VW change). The RTOTAL value for the device can temporarily be reduced by a significant amount if the wiper is moved several positions. When the device is powered-down, the last wiper position stored will be maintained in the nonvolatile memory. When power is restored, the contents of the memory are recalled and the wiper is set to the value last stored. www.xicor.com Characteristics subject to change without notice. 2 of 9 X9312 MODE SELECTION INSTRUCTIONS AND PROGRAMMING The INC, U/D and CS inputs control the movement of the wiper along the resistor array. With CS set LOW the device is selected and enabled to respond to the U/D and INC inputs. HIGH to LOW transitions on INC will increment or decrement (depending on the state of the U/D input) a seven bit counter. The output of this counter is decoded to select one of one hundred wiper positions along the resistive array. The value of the counter is stored in nonvolatile memory whenever CS transitions HIGH while the INC input is also HIGH. CS INC U/D Mode L H Wiper up L L Wiper down H X Store wiper position X X Standby current L X No store, return to standby H SYMBOL TABLE WAVEFORM The system may select the X9312, move the wiper and deselect the device without having to store the latest wiper position in nonvolatile memory. After the wiper movement is performed as described above and once the new position is reached, the system must keep INC LOW while taking CS HIGH. The new wiper position will be maintained until changed by the system or until a powerup/down cycle recalled the previously stored data. This procedure allows the system to always power-up to a preset value stored in nonvolatile memory; then during system operation minor adjustments could be made. The adjustments might be based on user preference, system parameter changes due to temperature drift, etc... INPUTS OUTPUTS Must be steady Will be steady May change from Low to High Will change from Low to High May change from High to Low Will change from High to Low Don't Care: Changes Allowed N/A Changing: State Not Known Center Line is High Impedance The state of U/D may be changed while CS remains LOW. This allows the host system to enable the device and then move the wiper up and down until the proper trim is attained. REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 3 of 9 X9312 ABSOLUTE MAXIMUM RATINGS COMMENT Temperature under bias ....................-65C to +135C Storage temperature .........................-65C to +150C Voltage on CS, INC, U/D and VCC with respect to VSS ................................. -1V to +7V V = |VH-VL|......................................................... 15V Lead temperature (soldering 10 seconds)..........300C IW (10 seconds) .............................................. 8.8mA Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only; functional operation of the device (at these or any other conditions above those listed in the operational sections of this specification) is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS Temperature Min. Max. Supply Voltage (VCC) Limits Commercial 0C +70C X9312 5V 10% Industrial -40C +85C POTENTIOMETER CHARACTERISTICS (Over recommended operating conditions unless otherwise stated.) Limits Symbol Parameter Min. Typ. End to end resistance tolerance Max. Unit Test Conditions/Notes 20 % VVH VH terminal voltage VSS 15 V VSS = 0V VVL VL terminal voltage VSS 15 V VSS = 0V Power rating 25 mW RTOTAL 10 K Power rating 225 mW RTOTAL = 1 K 100 4.4 mA RW Wiper resistance IW Wiper current Noise Resolution 40 -120 dBV 1 IW = 1mA, VCC = 5V Ref: 1kHz % Absolute linearity(1) 1 MI(3) Rw(n)(actual)-Rw(n)(expected) Relative linearity(2) 0.2 MI(3) Rw(n+1)-[Rw(n)+MI] RTOTAL temperature coefficient 300 Ratiometric temperature coefficient CH/CL/CW Potentiometer capacitances ppm/C 20 10/10/25 ppm/C pF See circuit #3 Notes: (1) Absolute linearity is utilized to determine actual wiper voltage versus expected voltage = (V w(n)(actual)-Vw(n)(expected)) = 1 Ml Maximum. (2) Relative linearity is a measure of the error in step size between taps = RW(n+1)-[Rw(n) + Ml] = 0.2 Ml. (3) 1 Ml = Minimum Increment = RTOT/99. REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 4 of 9 X9312 D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.) Limits Symbol Parameter Min. ICC VCC active current (Increment) ISB Standby supply current Typ.(4) Max. Unit 1 3 mA CS = VIL, U/D = VIL or VIH and INC = 0.4V/2.4V @ max. tCYC 500 1000 A CS = VCC - 0.3V, U/D and INC = VSS or VCC - 0.3V VIN = VSS to VCC ILI CS, INC, U/D input leakage current 10 A VIH CS, INC, U/D input HIGH voltage 2 VCC + 1 V VIL CS, INC, U/D input LOW voltage -1 0.8 V CIN(5) CS, INC, U/D input capacitance 10 pF Test Conditions VCC = 5V, VIN = VSS, TA = 25C, f = 1MHz ENDURANCE AND DATA RETENTION Parameter Min. Unit Minimum endurance 100,000 Data changes per bit Data retention 100 Years Notes: (4) Typical values are for TA = 25C and nominal supply voltage. (5) This parameter is periodically sampled and not 100% tested. Test Circuit #1 Test Circuit #2 VH/RH VH/RH VS Circuit #3 SPICE Macro Model Test Point Test Point VW/RW VLL/RL VL/RL VW/RW VW Force Current RTOTAL RH CW CH CL RL 10pF 25pF 10pF RW A.C. CONDITIONS OF TEST Input pulse levels 0V to 3V Input rise and fall times 10ns Input reference levels 1.5V REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 5 of 9 X9312 A.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified) Limits Symbol Parameter Typ.6 Min. Max. Unit tCl CS to INC setup 100 ns tlD INC HIGH to U/D change 100 ns tDI U/D to INC setup 1 s tlL INC LOW period 1 s tlH INC HIGH period 1 s tlC INC inactive to CS inactive 1 s tCPH CS deselect time (STORE) 20 ms tCPH CS deselect time (NO STORE) 100 ns tIW tCYC tR, tF7 tPU7 tR VCC7 INC to Vw change 100 INC cycle time 500 s 4 s INC input rise and fall time 500 s Power up to wiper stable 500 s 50 V/ms VCC power-up rate 0.2 POWER UP AND DOWN REQUIREMENTS There are no restrictions on the sequencing of VCC and the voltages applied to the potentiometer pins during power-up or power-down conditions. During power-up, the data sheet parameters for the DCP do not fully apply until 1 millisecond after VCC reaches is final value. The VCC ramp spec is always in effect. A.C. TIMING CS tCYC tCI tIL tIC tIH tCPH 90% 90% 10% INC tID tDI tF tR U/D tIW VW MI (8) Notes: (6) Typical values are for TA = 25C and nominal supply voltage. (7) This parameter is sample tested. (8) MI in the A.C. timing diagram refers to the minimum incremental change in the VW output due to a change in the wiper position. REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 6 of 9 X9312 APPLICATIONS INFORMATION Electronic digitally controlled (XDCP) potentiometers provide three powerful application advantages; (1) the variability and reliability of a solid-state potentiometer, (2) the flexibility of computer-based digital controls, and (3) the retentivity of nonvolatile memory used for the storage of multiple potentiometer settings or data. Basic Configurations of Electronic Potentiometers VR VR VH VW/RW VL I Three terminal potentiometer; variable voltage divider Two terminal variable resistor; variable current Basic Circuits Buffered Reference Voltage Noninverting Amplifier Cascading Techniques R1 +V +5V +V +V VS +5V VW VREF + VO - OP-07 VOUT - LM308A + -5V X VW/RW R2 +V -5V R1 VW/RW VOUT = VW/RW (a) Voltage Regulator VIN (b) VO = (1+R2/R1)VS Offset Voltage Adjustment VO (REG) 317 R1 Comparator with Hysteresis R2 VS R1 VS LT311A 100K - + VO - VO + Iadj 10K 10K VO (REG) = 1.25V (1+R2/R1)+Iadj R2 +12V } 10K } TL072 R2 R1 R2 VUL = {R1/(R1+R2)} VO(max) VLL = {R1/(R1+R2)} VO(min) -12V (for additional circuits see AN115) REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 7 of 9 X9312 PACKAGING INFORMATION 8-Lead Plastic Small Outline Gull Wing Package Type S 0.150 (3.80) 0.228 (5.80) 0.158 (4.00) 0.244 (6.20) Pin 1 Index Pin 1 0.014 (0.35) 0.019 (0.49) 0.188 (4.78) 0.197 (5.00) (4X) 7 0.053 (1.35) 0.069 (1.75) 0.004 (0.19) 0.010 (0.25) 0.050 (1.27) 0.010 (0.25) X 45 0.020 (0.50) 0.050"Typical 0.050" Typical 0 - 8 0.0075 (0.19) 0.010 (0.25) 0.250" 0.016 (0.410) 0.037 (0.937) 0.030" Typical 8 Places FOOTPRINT NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS) REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 8 of 9 X9312 ORDERING INFORMATION X9312X X X Temperature Range Blank = Commercial = 0C to +70C I = Industrial = -40C to +85C Package P = 8-Lead Plastic DIP S = 8-Lead SOIC End to End Resistance W= 10K U= 50K T= 100K Physical Characteristics Marking Includes Manufacturer's Trademark Resistance Value or Code Date Code LIMITED WARRANTY (c)Xicor, Inc. 2000 Patents Pending Devices sold by Xicor, Inc. are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale only. Xicor, Inc. makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. Xicor, Inc. makes no warranty of merchantability or fitness for any purpose. Xicor, Inc. reserves the right to discontinue production and change specifications and prices at any time and without notice. Xicor, Inc. assumes no responsibility for the use of any circuitry other than circuitry embodied in a Xicor, Inc. product. No other circuits, patents, or licenses are implied. TRADEMARK DISCLAIMER: Xicor and the Xicor logo are registered trademarks of Xicor, Inc. AutoStore, Direct Write, Block Lock, SerialFlash, MPS, and XDCP are also trademarks of Xicor, Inc. All others belong to their respective owners. U.S. PATENTS Xicor products are covered by one or more of the following U.S. Patents: 4,326,134; 4,393,481; 4,404,475; 4,450,402; 4,486,769; 4,488,060; 4,520,461; 4,533,846; 4,599,706; 4,617,652; 4,668,932; 4,752,912; 4,829,482; 4,874,967; 4,883,976; 4,980,859; 5,012,132; 5,003,197; 5,023,694; 5,084,667; 5,153,880; 5,153,691; 5,161,137; 5,219,774; 5,270,927; 5,324,676; 5,434,396; 5,544,103; 5,587,573; 5,835,409; 5,977,585. Foreign patents and additional patents pending. LIFE RELATED POLICY In situations where semiconductor component failure may endanger life, system designers using this product should design the system with appropriate error detection and correction, redundancy and back-up features to prevent such an occurrence. Xicor's products are not authorized for use in critical components in life support devices or systems. 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. REV 1.1.1 11/10/00 www.xicor.com Characteristics subject to change without notice. 9 of 9