AD5235BRU25

PRELIMINARY TECHNICAL DATA a FEATURES Dual, 1024 Position Resolution 25K, 250K Ohm Terminal Resistance with 50ppm/°C Tempco Nonvolatile Memory Preset SPI Compatible Serial Data Input with Readback Function Increment/Decrement Commands, Push Button Command +3 to +5V Single Supply Operation ±2.5V Dual Supply Operation 30 bytes of general purpose nonvolatile memory APPLICATIONS Mechanical Potentiometer Replacement Instrumentation: Gain, Offset Adjustment Programmable Voltage to Current Conversion Programmable Filters, Delays, Time Constants Line Impedance Matching Power Supply Adjustment DIP Switch Setting Nonvolatile Memory, Dual 1024 Position Digital Potentiometers AD5235 FUNCTIONAL BLOCK DIAGRAMS RDAC1 CS CLK SDI SDO SER IAL IN P U T R E G IS T E R ADDRESS DECODE V DD A1 W1 B1 RDAC1 REGISTER EEMEM1 RDAC2 PR PWR ON PRESET RDAC2 REGISTER A2 W2 B2 WP RDY EEMEM CONTROL EEMEM2 V SS G ND SPARE EEMEM G ND GENERAL DESCRIPTION The AD5235 provides a dual channel, digitally controlled variable resistor (VR) with resolutions of 1024 positions. These devices perform the same electronic adjustment function as a potentiometer or variable resistor. The AD5235’s versatile programming via a Micro Controller allows multiple modes of operation and adjustment. In the direct program mode a predetermined setting of the RDAC register can be loaded directly from the micro controller. Another key mode of operation allows the RDAC register to be refreshed with the setting previously stored in the EEMEM register. When changes are made to the RDAC register to establish a new wiper position, the value of the setting can be saved into the EEMEM by executing an EEMEM save operation. Once the settings are saved in the EEMEM register, these values will be transferred automatically to the RDAC register to set the wiper position at system power ON. Such operation is enabled by the internal preset strobe and the preset can also be accessed externally. An internal scratch pad RDAC register can be programmed by the micro controller to set the resistance between terminals W-and-B. Once the target value is achieved, the RDAC content register can be placed in the non-volatile memory for automatic recall during Power Up. The AD5235 is available in the thin TSSOP-16 package. All parts are guaranteed to operate over the extended industrial temperature range of -40°C to +85°C. REV PrD 6 Nov 2000 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106 U.S.A. Tel: 781/329-4700 Fax:781/326-8703 PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers = +VDD, VB = 0V, -40°C < TA < +85°C unless otherwise noted.) AD5235 Min -1 -2 -30 50 50 200 ELECTRICAL CHARACTERISTICS 25K, 250K OHM VERSIONS (VDD = +3V±10% or +5V±10% and VSS=0V, VA Parameter Resistor Differential NL2 Resistor Nonlinearity2 Nominal resistor tolerance Resistance Temperature Coefficent Wiper Resistance Wiper Resistance Symbol R-DNL R-INL ∆R RAB/∆T RW RW N INL DNL ∆VW/∆T VWFSE VWZSE VA,B,W CA,B CW ICM VIH VIL VOH VOH VOL IIL CIL VDD VDD/VSS IDD IDD(PG) IDD(READ) ISS PDISS PSS Conditions RWB, VA=NC RWB, VA=NC TA = 25°C, VAB = VDD,Wiper (VW) = No connect VAB = VDD, Wiper (VW) = No Connect IW = 1 V/R, VDD = +5V IW = 1 V/R, VDD = +3V Typ 1 Max +1 +2 30 100 Units LSB LSB % ppm/°C Ω Ω DC CHARACTERISTICS RHEOSTAT MODE Specifications apply to all VRs ±1/4 ±1/2 DC CHARACTERISTICS POTENTIOMETER DIVIDER MODE Specifications apply to all VRs Resolution Integral Nonlinearity3 Differential Nonlinearity3 Voltage Divider Temperature Coefficent Full-Scale Error Zero-Scale Error RESISTOR TERMINALS Voltage Range4 Capacitance5 Ax, Bx Capacitance5 Wx Common-mode Leakage Current7 DIGITAL INPUTS & OUTPUTS Input Logic High Input Logic Low Output Logic High Output Logic High Output Logic Low Input Current Input Capacitance5 POWER SUPPLIES Single-Supply Power Range Dual-Supply Power Range Positive Supply Current Programming Mode Current Read Mode Current Negative Supply Current Power Dissipation6 Power Supply Sensitivity DYNAMIC CHARACTERISTICS5, 7 Bandwidth –3dB Total Harmonic Distortion VW Settling Time Resistor Noise Voltage Crosstalk BW_25K THDW tS eN_WB CT R = 12KΩ VA =1Vrms, VB = 0V, f=1KHz VA= VDD, VB=0V, 50% of final value 25K/250K RWB = 10KΩ, f = 1KHz VA = VDD, VB = 0V, Measue VW with adjacent VR making full scale change 400 0.003 0.6/3/6 9 -65 KHz % µs nV√Hz dB VSS = 0V VSS = 0V VIH = VDD or VIL = GND VIH = VDD or VIL = GND VIH = VDD or VIL = GND VIH = VDD or VIL = GND, VDD = 2.5V, VSS = -2.5V VIH = VDD or VIL = GND ∆VDD = +5V ±10% 2.7 ±2.2 2 15 650 5.5 ±2.7 20 V V µA mA µA µA mW %/% with respect to GND with respect to GND RPULL-UP = 2.2KΩ to +5V IOH = 40µA, VLOGIC = +5V IOL = 1.6mA, VLOGIC = +5V VIN = 0V or VDD 0.3•VDD 0.7•VDD 4.9 4 0.4 ±1 5 V V V V V µA pF VSS f = 1 MHz, measured to GND, Code = Half-scale f = 1 MHz, measured to GND, Code = Half-scale VA = VB = VDD/2 45 60 0.01 1 VDD V pF pF µA 10 –2 –1 Code = Half-scale Code = Full-scale Code = Zero-scale –3 0 ±1/2 ±1/4 15 -1 +1 +2 +1 +0 +3 Bits LSB LSB ppm/°C LSB LSB 10 0.002 0.05 0.01 REV PrD 6 NOV, 2000 2 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers = +VDD, VB = 0V, -40°C < TA < +85°C unless otherwise noted.) AD5235 Min 20 10 10 5 5 0 10 10 1 Typ 1 ELECTRICAL CHARACTERISTICS 25K, 250K OHM VERSIONS (VDD = +3V±10% to +5V±10% and VSS=0V, VA Parameter Clock Cycle Time Input Clock Pulse Width CS Setup Time Data Setup Time Data Hold Time CLK Shutdown Time CS Rise to Clock Rise Setup CS High Pulse Width CLK to SDO Propagation Delay9 Store to Nonvolatile EEMEM Save Time10 CS to SDO - SPI line acquire CS to SDO - SPI line release RDY Rise to CLK Rise Startup Time CLK Setup Time Preset Pulse Width NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Typicals represent average readings at +25°C and VDD = +5V. Resistor position nonlinearity error R-INL is the deviation from an ideal value measured between the maximum resistance and the minimum resistance wiper positions. R-DNL measures the relative step change from ideal between successive tap positions. Parts are guaranteed monotonic. See figure 20 test circuit. IW = VDD/R for both VDD=+3V or VDD=+5V. INL and DNL are measured at VW with the RDAC configured as a potentiometer divider similar to a voltage output D/A converter. VA = VDD and VB = 0V. DNL specification limits of ±1LSB maximum are Guaranteed Monotonic operating conditions. See Figure 19 test circuit. Resistor terminals A,B,W have no limitations on polarity with respect to each other. Guaranteed by design and not subject to production test. PDISS is calculated from (IDD x VDD=+5V). All dynamic characteristics use VDD = +5V. See timing diagram for location of measured values. All input control voltages are specified with tR=tF=2.5ns(10% to 90% of 3V) and timed from a voltage level of 1.5V. Switching characteristics are measured using both VDD = +3V or +5V. Propagation delay depends on value of VDD, RPULL_UP, and CL see applications text. Low only for commands 8, 9,10, 2, 3: CMD_8 ~ 1ms; CMD_9,10 ~0.1ms; CMD_2,3 ~20ms. Symbol t1 t 2, t 3 t4 t5 t6 t7 t8 t9 t 10 t 11 t 12 t 13 t 14 t 15 t 16 tPR Conditions Max Units ns ns ns ns ns ns ns ns ns ms ns ns ns ms ns ns INTERFACE TIMING CHARACTERISTICS applies to all parts(Notes 5, 8) Clock level high or low From Positive CLK transition From Positive CLK transition RL = 1KΩ, CL < 20pF Applies to Command 2H, 3H 25 25 For 1 CLK period (t4 - t3 = 1 CLK period) 50 Timing Diagram CLK t 16 t4 t1 t3 t2 t8 t7 t9 t5 t6 CS SDI t 12 MSB t 10 LSB t 13 SDO 1 MSB MSB t 14 LSB LSB t 15 t 11 S D O2 RDY SDO 1 C LK IDLES LOW SDO 2 C LK IDLES HIGH Figure 1. Timing Diagram REV PrD 6 NOV, 2000 3 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers Absolute Maximum Rating (TA = +25°C, unless otherwise noted) VDD to GND..............................................................-0.3, +7V VSS to GND ................................................................. 0V, -7V VDD to VSS ......................................................................... +7V VA, VB, VW to GND ................................................. VSS, VDD AX – BX, AX – WX, BX – WX ...................................... ±20mA Ox to GND...................................................................0V, VDD Digital Inputs & Output Voltage to GND .................. 0V, +7V Operating Temperature Range......................... -40°C to +85°C Maximum Junction Temperature (TJ MAX)...................+150°C Storage Temperature ..................................... -65°C to +150°C Lead Temperature (Soldering, 10 sec)..........................+300°C Thermal Resistance θJA, TSSOP-16...................................................... 180°C/W Package Power Dissipation = (TJMAX - TA) / θJA CLK SDI SDO GND VSS A1 W1 B1 1 2 3 4 5 6 7 8 15 CS CS 14 PR 13 WP WP 12 VDD 11 A2 10 W2 9 B2 AD5235 AD5235 PIN CONFIGURATION 16 RDY AD5235 PIN FUNCTION DESCRIPTION # Name Description 1 2 CLK SDI SDO Serial Input Register clock pin. Shifts in one bit at a time on positive clock edges. Serial Data Input Pin. Shifts in one bit at a time on positive clock CLK edges. Serial Data Output Pin. Open Drain Output requires external pull-up resistor. Commands 9 and 10 activate the SDO output. See Instruction operation Truth Table. Table 2. Ground pin, logic ground reference Negative Supply. Connect to zero volts for single supply applications. A terminal of RDAC1. Wiper terminal of RDAC1, ADDR(RDAC1) = 0H. B terminal of RDAC1. B terminal of RDAC2. Wiper terminal of RDAC2, ADDR(RDAC3) = 1H. A terminal of RDAC2. Positive Power Supply Pin. Should be ≥ the input-logic HIGH voltage. Write Protect Pin. Prevents any changes to the present EEMEM contents when active low. Hardware over ride preset pin. Refreshes the scratch pad register with current contents of the EEMEM register. Factory default loads midscale 51210. Serial Register chip select active low. Serial register operation takes place when CS returns to logic high. Ready. Active-high open drain output. Identifies completion of commands 2, 3, 8, 9, 10. Ordering Guide Model #CHs/ k Ohm Temp Range Package Package Description Option RU-16 RU-16 3 AD5235BRU25 X2/25 AD5235BRU250 X2/250 -40/+85°C TSSOP-16 -40/+85°C TSSOP-16 4 5 6 7 8 9 10 11 12 13 14 GND VSS A1 W1 B1 B2 W2 A2 VDD WP PR The AD5235 contains 16,000 transistors. Die size: 100 x 105 mil = 10,500 sq. mil 15 CS 16 RDY REV PrD 6 NOV, 2000 4 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers OPERATIONAL OVERVIEW The AD5235 digital potentiometer is designed to operate as a true variable resistor replacement device for analog signals that remain within the terminal voltage range of VSS > X X X X Data Byte 1 B15 •••• B8 X ••• D9 D8 X ••• X X X ••• X X ••• X X X Data Byte 0 B7 ••• B0 D7 ••• D0 X ••• X X X ••• X ••• X Operation AD5235 NOP: Do nothing Write contents of EEMEM(ADDR) to RDAC(ADDR) Register SAVE WIPER SETTING: Write contents of RDAC(ADDR) to EEMEM(ADDR) Write contents of Serial Register Data Byte 0 & 1 to EEMEM(ADDR) DEC 6dB: Right Shift contents of RDAC(ADDR) , LSB rolls over to MSB position DEC All 6dB: Right Shift contents of all RDAC Registers, LSB rolls over to MSB position Decrement contents of RDAC(ADDR) by One, does not rollover at zero-scale Decrement contents of all RDAC Registers by One, does not rollover at zero-scale RESET: Load all RDACs with their corresponding EEMEM previously-saved values Write contents of EEMEM(ADDR) to Serial Register Data Byte 0 & 1 Write contents of RDAC(ADDR) to Serial Register Data Byte 0 & 1 Write contents of Serial Register Data Byte 0 &1 to RDAC(ADDR) INC 6dB: Left Shift contents of RDAC(ADDR), stops at all 'Ones'. INC All 6dB: Right Shift contents of all RDAC Registers, stops at all 'Ones'. Increment contents of RDAC(ADDR) by One, does not rollover at full-scale stops at all 'Ones'. Increment contents of all RDAC Registers by One, does not rollover at full-scale stops at all 'Ones'. X ••• D9 D8 X ••• X X ••• X X ••• X X ••• X X ••• X X ••• X X ••• X X X X X X X X D7 ••• D0 X X X X X X X ••• X ••• X ••• X ••• X ••• X ••• X ••• X > X 0 X 0 X 0 X 0 > > > > X X X X X ••• D9 D8 X ••• X X ••• X X ••• X X ••• X X X X X D7 ••• D0 X X X X ••• X ••• X ••• X ••• X > X X X X NOTES: 1. The SDO output shifts-out the last 24-bits of data clocked into the serial register for daisy chain operation. Exception, following Instruction #9 or #10 the selected internal register data will be present in data byte 0 & 1. Instructions following #9 & #10 must be a full 24-bit data word to completely clock out the contents of the serial register. 2. The RDAC register is a volatile scratch pad register that is refreshed at power ON from the corresponding non-volatile EEMEM register. 3. The increment, decrement and shift commands ignore the contents of the shift register Data Byte 0. 4. Execution of the Operation column noted in the table takes place when the CS strobe returns to logic high. . REV PrD 6 NOV, 2000 6 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers Detail Potentiometer Operation The actual structure of the RDAC is designed to emulate the performance of a mechanical potentiometer. The RDAC contains a string of connected resistor segments, with an array of analog switches that act as the wiper connection to several points along the resistor array. The number of points is the resolution of the device. The AD5235 has 1024 connection points allowing it to provide better than 0.5% set-ability resolution. Figure 3 provides an equivalent diagram of the connections between the three terminals that make up one channel of the RDAC. The SWA and SWB will always be ON while one of the switches SW(0) to SW(2N-1) will be ON one at a time depends upon the resistance step decoded from the Data Bits. Note that there are two 50Ω wiper resistances, RW. The resistance contributed by RW must be accounted for when calculating the output resistance. RW is the sum of the resistances of SWA + SWX and SWB + SWX for A-to-Wiper and B-to-Wiper respectively. SW A ladder until the last tap point is reached at RWB=25025Ω. See figure 3 for a simplified diagram of the equivalent RDAC circuit. The general equation, which determines the digitally programmed output resistance between Wx and Bx, is: RWB(Dx) = (Dx/2N) * RAB + RW eqn. 1 AD5235 Where N is the resolution of the VR, Dx is the data contained in the RDACx latch, and RAB is the nominal end-to-end resistance. Since N=10 and RW=50Ω for AD5235, eqn. 1 becomes: RWB(Dx) = (Dx/1024) * RAB + 50Ω eqn. 2 For example, when VB = 0V and A–terminal is open circuit the following output resistance values will be set for the following RDAC latch codes (applies to RAB=25KΩ potentiometers): Dx (DEC) 1023 512 1 0 RWB (Ω) 25025Ω 12500Ω 74Ω 50Ω Output State AX SW(2 N -1) RDAC WIPER REGISTER & DECODER RS SW(2 N -2) WX Full-Scale Mid-Scale 1 LSB Zero-Scale (Wiper contact resistance) RS SW(1 ) Note that in the zero-scale condition a finite wiper resistance of 50Ω is present. Care should be taken to limit the current flow between W and B in this state to no more than 20mA to avoid degradation or possible destruction of the internal switch contact. RS SW(0 ) RS = R AB /2 N DIGITAL CIRCUITRY OMITTED FOR CLARITY SW B BX Figure 3. Equivalent RDAC structure PROGRAMMING THE VARIABLE RESISTOR Rheostat Operation The nominal resistance of the RDAC between terminals A and B are available with values of 25KΩ, and 250KΩ. The final digits of the part number determine the nominal resistance value, e.g., 25KΩ = 25; 250KΩ = 250. The nominal resistance (RAB) of the AD5235 VR has 1024 contact points accessed by the wiper terminal, plus the B terminal contact. The 10-bit data word in the RDAC latch is decoded to select one of the 1024 possible settings. The wiper's first connection starts at the B terminal for data 00H. This B– terminal connection has a wiper contact resistance, RW of 50Ω, regardless of what the nominal resistance RAB is. The second connection (25KΩ part) is the first tap point where RWB =74Ω [RWB =RAB/1024 + RW = 24Ω+50Ω)] for data 01H. The third connection is the next tap point representing RWB =49+50=99Ω for data 02H. Each LSB data value increase moves the wiper up the resistor Figure 4. Symmetrical RDAC Operation Like the mechanical potentiometer the RDAC replaces, the AD5235 part is totally symmetrical. The resistance between the wiper W and terminal A also produces a digitally controlled resistance RWA. Figure 4 shows the symmetrical programmability of the various terminal connections. When these terminals are used, the B–terminal should be tied to the wiper. Setting the resistance value for RWA starts at a maximum value of resistance and decreases as the data loaded in the latch is increased in value. The general equation for this operation is: REV PrD 6 NOV, 2000 7 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA RWA(Dx) = [ (2N-Dx)/2N ] * RAB + RW Similarly, eqn. 3 becomes: RWA(Dx) = [ (1024-Dx)/1024 ] * RAB + 50Ω eqn. 4 L O G IC P IN S IN P U T S Nonvolatile Memory Digital Potentiometers eqn. 3 ESD PROTECTION CIRCUITS AD5235 VDD For example, when VA = 0V and B–terminal is tied to the wiper W the following output resistance values will be set for the following RDAC latch codes (applies to RAB=10KΩ potentiometers): Dx (DEC) 1023 512 1 0 RWA (Ω) 74 12500 25000 25050 Output State GND Figure 5A. Equivalent Digital Input ESD Protection Full-Scale Mid-Scale 1 LSB Zero-Scale V DD O UTPU TS O1 & O2 P IN S A ±1% typical distribution of RAB from channel-to-channel occurs within the same package. On the other hand, device to device matching is process lot dependent such that a maximum of ±30% variation is possible. The change in RAB with temperature has a 50 ppm/°C temperature coefficient. PROGRAMMING THE POTENTIOMETER DIVIDER Voltage Output Operation The digital potentiometer easily generates an output voltage proportional to the input voltage applied to a given terminal. For example connecting A–terminal to +5V and B–terminal to ground produces an output voltage at the wiper which can be any value starting at zero volts and up to 1 LSB less than +5V. Each LSB of voltage is equal to the voltage applied across terminal AB divided by the 2N resolution of the potentiometer divider. The general equation defining the output voltage with respect to ground for any given input voltage applied to terminals AB is: VW(Dx) = Dx/2N * VAB + VB eqn. 5 Since N=10, VW(Dx) = (Dx/1024) * VAB + VB eqn. 6 GND Figure 5B. Equivalent Digital Output ESD Protection VDD O U TPUTS SDO P IN GND Figure 5C. Equivalent SDO Output ESD Protection Circuit Figure 5 shows the equivalent ESD protection circuit for digital pins. Figure 6 shows the equivalent analog-terminal protection circuit for the variable resistors. P O T E N T IO M E T E R T E R M IN A L S A, B, W P IN S Operation of the digital potentiometer in the divider mode results in more accurate operation over temperature. Here the output voltage is dependent on the ratio of the internal resistors and not the absolute value. Therefore, the drift reduces to 15ppm/°C. V SS Figure 6. Equivalent VR-Terminal ESD Protection REV PrD 6 NOV, 2000 8 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers TEST CIRCUITS Figures 7 to 15 define the test conditions used in the product specification's table. AD5235 Figure 12. Non-Inverting Gain test circuit Figure 7. Potentiometer Divider Nonlinearity error test circuit (INL, DNL) Figure 13. Gain Vs Frequency test circuit Figure 8. Resistor Position Nonlinearity Error (Rheostat Operation; R-INL, R-DNL) Figure 14. Incremental ON Resistance Test Circuit Figure 9. Wiper Resistance test Circuit Figure 15. Common Mode Leakage current test circuit Figure 10. Power supply sensitivity test circuit (PSS, PSSR) TYPICAL PERFORMANCE GRAPHS TBD Figure 11. Inverting Gain test Circuit REV PrD 6 NOV, 2000 9 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com PRELIMINARY TECHNICAL DATA Nonvolatile Memory Digital Potentiometers OUTLINE DIMENSIONS Dimensions shown in inches and (mm) AD5235 REV PrD 6 NOV, 2000 10 Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL(408)562-7254; FAX (408)727-1550; walt.heinzer@analog.com