64-Position OTP Digital Potentiometer AD5273 FEATURES FUNCTIONAL BLOCK DIAGRAM 64 positions One-time programmable (OTP) 1 set-and-forget Resistance setting--low cost alternative over EEMEM Unlimited adjustments prior to OTP activation 1 k, 10 k, 50 k, 100 k end-to-end terminal resistance Compact 8-lead SOT-23 standard package Ultralow power: IDD = 5 A maximum Fast settling time: tS = 5 s typical during power-up I2C-compatible digital interface Computer software 2 replaces microcontroller in factory programming applications Wide temperature range: -40C to +105C Low operating voltage: 2.7 V to 5.5 V OTP validation check function APPLICATIONS System calibrations Electronics level settings Mechanical potentiometers and trimmer replacement Automotive electronics adjustments Transducer circuit adjustments Programmable filters up to 6 MHz BW 3 GENERAL DESCRIPTION The AD5273 is a 64-position, one-time programmable (OTP) digital potentiometer 4 that employs fuse link technology to achieve permanent program setting. This device performs the same electronic adjustment function as most mechanical trimmers and variable resistors. It allows unlimited adjustments before permanently setting the resistance values. The AD5273 is programmed using a 2-wire, I2C-compatible digital control. During write mode, a fuse blow command is executed after the final value is determined, thereby freezing the wiper position at a given setting (analogous to placing epoxy on a mechanical trimmer). When the permanent setting is achieved, the value does not change, regardless of the supply variations or environmental stresses under normal operating conditions. To verify the success of permanent programming, Analog Devices, Inc., patterned the OTP validation such that the fuse status can be discerned from two validation bits in the read mode. SCL AD0 A I2C INTERFACE AND CONTROL LOGIC B AD5273 WIPER REGISTER VDD GND W 03224-001 SDA FUSE LINK Figure 1. In addition, for applications that program the AD5273 at the factory, Analog Devices offers device programming software2 running on Windows(R) NT, Windows 2000, and Windows XP operating systems. This software application effectively replaces any external I2C controllers, which in turn enhances the user system's time-to-market. The AD5273 is available in 1 k, 10 k, 50 k, and 100 k resistances and in a compact 8-lead SOT-23 standard package. It operates from -40C to +105C. Along with its unique OTP feature, the AD5273 lends itself well to general digital potentiometer applications due to its effective resolution, array resistance options, small footprint, and low cost. An AD5273 evaluation kit and software are available. The kit includes the connector and cable that can be converted for factory programming applications. For applications that require dynamic adjustment of resistance settings with nonvolatile EEMEM, users should refer to the AD523x and AD525x families of nonvolatile memory digital potentiometers. 1 OTP allows unlimited adjustments before permanent setting. Analog Devices cannot guarantee the software to be 100% compatible to all systems due to the wide variation in computer configurations. 3 Applies to 1 k parts only. 4 The terms digital potentiometer, VR, and RDAC are used interchangeably. 2 Rev. H 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 that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2002-2010 Analog Devices, Inc. All rights reserved. AD5273 TABLE OF CONTENTS Features .............................................................................................. 1 Power Supply Considerations ................................................... 15 Applications ....................................................................................... 1 Controlling the AD5273 ................................................................ 16 General Description ......................................................................... 1 Software Programming ............................................................. 16 Functional Block Diagram .............................................................. 1 I2C Controller Programming .................................................... 17 Revision History ............................................................................... 2 Controlling Two Devices on One Bus ..................................... 18 Specifications..................................................................................... 4 Applications Information .............................................................. 19 Absolute Maximum Ratings............................................................ 6 DAC.............................................................................................. 19 ESD Caution .................................................................................. 6 Programmable Voltage Source with Boosted Output ........... 19 Pin Configuration and Function Descriptions ............................. 7 Programmable Current Source ................................................ 19 Typical Performance Characteristics ............................................. 8 Gain Control Compensation .................................................... 19 Theory of Operation ...................................................................... 13 Programmable Low-Pass Filter ................................................ 20 One-Time Programming ........................................................... 13 Level Shift for Different Voltages Operation .......................... 20 Variable Resistance and Voltage for Rheostat Mode ............. 14 RDAC Circuit Simulation Model ............................................. 20 Variable Resistance and Voltage for Potentiometer Mode .... 14 Evaluation Board ............................................................................ 21 ESD Protection ........................................................................... 15 Outline Dimensions ....................................................................... 22 Terminal Voltage Operating Range.......................................... 15 Ordering Guide .......................................................................... 22 Power-Up/Power-Down Sequences ......................................... 15 REVISION HISTORY 10/10--Rev. G to Rev. H Changes to OTP Power Supply Parameter in Table 1 .................. 4 Changes to VDD Pin Description in Table 3................................... 7 Changes to One-Time Programming Section ............................ 13 Changes to Power Supply Considerations Section, Figure 38 .. 15 Updated Outline Dimensions ....................................................... 22 Changes to Ordering Guide .......................................................... 22 8/08--Rev. F to Rev. G Changes to Power Supplies Parameter in Table 1......................... 3 Updated Fuse Blow Condition to 400 ms Throughout ............... 5 1/08--Rev. E to Rev. F Changes to Table 1 ............................................................................ 4 Changes to Table 2 ............................................................................ 6 Changes to Table 3 ............................................................................ 7 Inserted Figure 28 ........................................................................... 12 Changes to One-Time Programming Section ............................ 13 Changes to Power Supply Considerations Section..................... 15 Deleted Figure 35 ............................................................................ 15 Changes to Figure 36 ...................................................................... 15 Updated Outline Dimensions ....................................................... 22 Changes to Ordering Guide .......................................................... 22 1/05--Rev. D to Rev. E Changes to Features ..........................................................................1 Changes to Specifications .................................................................3 Changes to Table 3.............................................................................6 Changes to Power Supply Considerations Section .................... 15 Changes to Figure 35 and Figure 37............................................. 15 Changes to DAC Section ............................................................... 19 Changes to Level Shift for Different Voltages Operation Section........................................................................... 20 Deleted the Resistance Scaling Section ....................................... 20 Deleted the Resolution Enhancement Section ........................... 20 12/04--Rev. C to Rev. D Updated Format .................................................................. Universal Changes to Specifications .................................................................3 Changes to Theory of Operation Section.................................... 13 Changes to Power Supply Considerations Section .................... 15 Changes to Figure 35, Figure 36, and Figure 37 ......................... 15 11/03--Rev. B to Rev. C Changes to SDA Bit Definitions and Descriptions .................... 10 Changes to One-Time Programming (OTP) Section................ 11 Changes to Table III ....................................................................... 11 Changes to Power Supply Considerations .................................. 13 Changes to Figure 8, Figure 9, and Figure 10 ............................. 13 Rev. H | Page 2 of 24 AD5273 10/03--Rev. A to Rev. B Changes to Features .......................................................................... 1 Changes to Applications ................................................................... 1 Changes to Specifications ................................................................. 2 Changes to Absolute Maximum Ratings ........................................ 4 Changes to Pin Function Descriptions........................................... 5 Changes to TPC 7, TPC 8, TPC 13, and TPC 14 Captions ......... 7 Deleted TPC 20; Renumbered Successive TPCs ........................... 9 Change to TPC 21 Caption .............................................................. 9 Change to the SDA Bit Definitions and Descriptions ................10 Replaced Theory of Operation Section ........................................11 Replaced Determining the Variable Resistance and Voltage Section ................................................................................11 Replaced ESD Protection Section ................................................. 12 Replaced Terminal Voltage Operating Range Section ............... 12 Replaced Power-Up Sequence Section ......................................... 12 Replaced Power Supply Considerations Section ......................... 13 Changes to Application Section .................................................... 16 Change to Equation 9 ..................................................................... 17 Deleted Digital Potentiometer Family Selection Guide ............. 19 6/03--Rev. 0 to Rev. A Change to Specifications .................................................................. 2 Change to Power Supply Considerations Section ....................... 12 Updated Outline Dimensions........................................................ 20 12/02--Revision 0: Initial Version Rev. H | Page 3 of 24 AD5273 SPECIFICATIONS VDD = 2.7 V to 5.5 V, VA < VDD, VB = 0 V, -40C < TA < +105C, unless otherwise noted. Table 1. Parameter DC CHARACTERISTICS--RHEOSTAT MODE Resolution Resistor Differential Nonlinearity 2 10 k, 50 k, 100 k 1 k Resistor Nonlinearity2 10 k, 50 k, 100 k 1 k Nominal Resistance Tolerance 3 10 k, 50 k, 100 k Nominal Resistance, 1 k Rheostat Mode Temperature Coefficient 4 Wiper Resistance DC CHARACTERISTICS--POTENTIOMETER DIVIDER MODE Differential Nonlinearity 5 Integral Nonlinearity5 Voltage Divider4 Temperature Coefficient Full-Scale Error 10 k, 50 k, 100 k 1 k Zero-Scale Error 10 k, 50 k, 100 k 1 k RESISTOR TERMINALS Voltage Range 6 Capacitance 7 A, B Capacitance7 W Common-Mode Leakage DIGITAL INPUTS AND OUTPUTS Input Logic High (SDA and SCL) 8 Input Logic Low (SDA and SCL)8 Input Logic High (AD0) Input Logic Low (AD0) Input Logic Current Input Capacitance7 Output Logic Low (SDA) Three-State Leakage Current Output Capacitance7 POWER SUPPLIES Power Supply Range OTP Power Supply8, 9 Supply Current OTP Supply Current8, 10,11 Symbol Test Conditions/Comments Min Typ 1 N R-DNL Max Unit 6 Bits RWB, VA = NC RWB, VA = NC -0.5 -1 +0.05 +0.25 +0.5 +1 LSB LSB RWB, VA = NC RWB, VA = NC TA = 25C -0.5 -5 +0.10 +2 +0.5 +5 LSB LSB +30 1.6 % k ppm/C R-INL RAB/RAB -30 0.8 RAB (RAB/RAB)/T Wiper = NC 1.2 300 RW IW = VDD/R, VDD = 3 V or 5 V 60 100 +0.1 +0.5 +0.5 LSB LSB ppm/C LSB LSB LSB LSB LSB LSB DNL INL (VW/VW)/T VWFSE Code = 0x20 Code = 0x3F VWZSE Code = 0x00 VA, VB, VW CA, CB CW ICM VIH VIL VIH VIL IIL CIL VOL IOZ COZ VDD VDD_OTP IDD IDD_OTP -0.5 -0.5 10 -1 -1 -6 -6 0 0 0 0 0 0 1 5 GND f = 5 MHz, measured to GND, code = 0x20 f = 1 MHz, measured to GND, code = 0x20 V A = VB = V W VIN = 0 V or 5 V 25 VDD V pF 55 pF 1 nA 0.7 x VDD -0.5 3.0 0 0.01 3 VDD + 0.5 0.3 x VDD VDD 0.4 1 0.4 1 3 2.7 TA = 25C 1 k (DD8), 10 k (DD9) 50 k (DYG), 100 k (DYH) VIH = 5 V or VIL = 0 V TA = 25C, VDD_OTP = 5 V Rev. H | Page 4 of 24 5.0 4.75 5.25 5.0 0.1 100 V V V V A pF V A pF 5.5 V 5.5 5.25 5 V V A mA AD5273 Parameter Power Dissipation12 Power Supply Sensitivity Symbol PDISS PSRR PSRR Test Conditions/Comments VIH = 5 V or VIL = 0 V, VDD = 5 V RAB = 1 k RAB = 10 k, 50 k, 100 k Total Harmonic Distortion BW_1 k BW_10 k BW_50 k BW_100 k THDW Adjustment Settling Time tS1 RAB = 1 k, code = 0x20 RAB = 10 k, code = 0x20 RAB = 50 k, code = 0x20 RAB = 100 k, code = 0x20 VA = 1 V rms, RAB = 1 k, VB = 0 V, f = 1 kHz VA = 5 V 1 LSB error band, VB = 0 V, measured at VW VA = 5 V 1 LSB error band, VB = 0 V, measured at VW, VDD = 5 V RAB = 1 k, f = 1 kHz, code = 0x20 Applies to all parts DYNAMIC CHARACTERISTICS7, 13, 14 Bandwidth, -3 dB Power-Up Settling Time-- After Fuses Blown Resistor Noise Voltage INTERFACE TIMING CHARACTERISTICS7, 14, 15 SCL Clock Frequency tBUF Bus Free Time Between Stop and Start tHD; STA Hold Time (Repeated Start) tLOW Low Period of SCL Clock tHIGH High Period of SCL Clock tSU; STA Setup Time for Start Condition tHD; DAT Data Hold Time tSU; DAT Data Setup Time tF Fall Time of Both SDA and SCL Signals tR Rise Time of Both SDA and SCL Signals tSU; STO Setup Time for Stop Condition OTP Program Time tS2 eN_WB fSCL t1 t2 Min Typ1 0.5 -0.3 -0.05 Max 27.5 +0.3 +0.05 6000 600 110 60 0.05 kHz kHz kHz kHz % 5 s 5 s 3 nV/Hz 400 After this period, the first clock pulse is generated 1.3 kHz s 0.6 s t3 t4 t5 1.3 0.6 0.6 t6 t7 t8 0.1 50 0.9 t9 t10 t11 0.6 400 1 Unit W %/% %/% s s s 0.3 s s s 0.3 s s ms Typical values represent average readings at 25C, VDD = 5 V, and VSS = 0 V. 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. 3 VAB = VDD, wiper (VW) = no connect. 4 RWB/T = RWA/T. Temperature coefficient is code-dependent; see the Typical Performance Characteristics section. 5 INL and DNL are measured at VW. INL with the RDAC configured as a potentiometer divider similar to a voltage output DAC. VW with the RDAC configured as a potentiometer divider similar to a voltage output DAC. VA = VDD and VB = 0 V. DNL specification limits of 1 LSB maximum are guaranteed monotonic operating conditions. 6 The A, B, and W resistor terminals have no limitations on polarity with respect to each other. 7 Guaranteed by design; not subject to production test. 8 The minimum voltage requirement on the VIH is 0.7 x VDD. For example, VIH min = 3.5 V when VDD = 5 V. It is typical for the SCL and SDA resistors to be pulled up to VDD. However, care must be taken to ensure that the minimum VIH is met when the SCL and SDA are driven directly from a low voltage logic controller without pull-up resistors. 9 Different from the operating power supply; the power supply for OTP is used one time only. 10 Different from the operating current; the supply current for OTP lasts approximately 400 ms for the one time it is needed. 11 See Figure 28 for the energy plot during the OTP program. 12 PDISS is calculated from (IDD x VDD). CMOS logic level inputs result in minimum power dissipation. 13 Bandwidth, noise, and settling time depend on the terminal resistance value chosen. The lowest R value results in the fastest settling time and highest bandwidth. The highest R value results in the minimum overall power consumption. 14 All dynamic characteristics use VDD = 5 V. 15 See Figure 29 for the location of the measured values. 2 Rev. H | Page 5 of 24 AD5273 ABSOLUTE MAXIMUM RATINGS TA = 25C, unless otherwise noted. Table 2. Parameter VDD to GND VA, VB, VW to GND Maximum Current IWB, IWA Pulsed IWB Continuous (RWB 1 k, A Open) 1 IWA Continuous (RWA 1 k, B Open) Digital Input and Output Voltage to GND Operating Temperature Range Maximum Junction Temperature (TJ max) Storage Temperature Reflow Soldering Peak Temperature Time at Peak Temperature Thermal Resistance JA, SOT-23 2 Rating -0.3 V +6.5 V GND, VDD 20 mA 4 mA 4 mA 0 V, VDD -40C to +105C 150C -65C to +150C 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 indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION 260C 20 sec to 40 sec 230C/W 1 Maximum terminal current is bounded by the maximum current handling of the switches, the maximum power dissipation of the package; the maximum applied voltage across any two of the A, B, and W terminals at a given resistance. 2 Package power dissipation = (TJ max - TA)/JA. Rev. H | Page 6 of 24 AD5273 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS W 1 8 AD5273 A B TOP VIEW GND 3 (Not to Scale) 6 AD0 SCL 4 7 5 SDA 03224-002 VDD 2 Figure 2. Pin Configuration Table 3. Pin Function Descriptions Pin No. 1 2 Mnemonic W VDD 3 4 GND SCL 5 SDA 6 7 8 AD0 B A Description Wiper Terminal W. GND VW VDD. Positive Power Supply. Specified for non-OTP operation from 2.7 V to 5.5 V. For OTP programming, VDD_OTP must be set within the window of 5 V to 5.5 V for the 1 k (DD8) and 10 k (DD9) options, or within the window of 4.75 V to 5.25 V for the 50 k (DYG) and 100 k (DYH) options, and be capable of sourcing 100 mA. Common Ground. Serial Clock Input. Requires a pull-up resistor. If it is driven directly from a logic controller without the pull-up resistor, ensure that the VIH minimum is 0.7 x VDD. Serial Data Input/Output. Requires a pull-up resistor. If it is driven directly from a logic controller without the pull-up resistor, ensure that the VIH minimum is 0.7 x VDD. I2C Device Address Bit. Allows a maximum of two AD5273 devices to be addressed. Resistor Terminal B. GND VB VDD. Resistor Terminal A. GND VA VDD. Rev. H | Page 7 of 24 AD5273 TYPICAL PERFORMANCE CHARACTERISTICS 0.5 0.10 RAB = 10k 0.3 VDD = 3V 0.1 -0.1 VDD = 5V -0.5 03224-003 -0.3 0 8 16 24 32 40 CODE (Decimal) 48 56 0.06 TA = +85C TA = +125C 0.02 -0.02 TA = +25C -0.06 -0.10 64 TA = -40C 03224-006 POTENTIOMETER MODE DNL (LSB) RHEOSTAT MODE INL (LSB) RAB = 10k TA = 25C 0 Figure 3. RINL vs. Code vs. Supply Voltages 24 32 40 CODE (Decimal) 48 VDD = 5V 0.05 -0.05 VDD = 3V 03224-004 -0.15 0 8 16 24 32 40 CODE (Decimal) 48 56 RAB = 10k TA = 25C 0.06 3V 0.02 -0.06 -0.10 64 5V -0.02 0 Figure 4. RDNL vs. Code vs. Supply Voltages 8 16 24 32 40 CODE (Decimal) 48 56 64 Figure 7. INL vs. Code vs. Supply Voltages 0.10 0.10 0.06 TA = +85C TA = +125C 0.02 -0.02 TA = +25C TA = -40C 03224-005 -0.06 0 8 16 24 32 40 CODE (Decimal) 48 56 RAB = 10k TA = 25C 0.06 3V 0.02 -0.02 5V -0.06 -0.10 64 Figure 5. INL vs. Code vs. Temperature 03224-008 POTENTIOMETER MODE DNL (LSB) RAB = 10k POTENTIOMETER MODE INL (LSB) 64 03224-007 POTENTIOMETER MODE INL (LSB) 0.15 -0.10 56 0.10 RAB = 10k TA = 25C RHEOSTAT MODE DNL (LSB) 16 Figure 6. DNL vs. Code vs. Temperature 0.25 -0.25 8 0 8 16 24 32 40 CODE (Decimal) 48 Figure 8. DNL vs. Code vs. Supply Voltages Rev. H | Page 8 of 24 56 64 AD5273 1.0 TA = 25C RAB = 10k CODE = 0x20 0.020 RAB = 10k 0.9 0.8 0.7 ZSE (LSB) 0.015 0.010 0.6 0.5 VDD = 3V 0.4 VDD = 5V 0.3 0.005 0 1 2 3 4 SUPPLY VOLTAGE (V) 5 03224-012 0 0.2 03224-009 POTENTIOMETER MODE LINEARITY (LSB) 0.025 0.1 0 -40 6 Figure 9. INL vs. Supply Voltage 100 SUPPLY CURRENT (A) 0.3 VDD = 5.5V RAB = 10k 0.14 0.2 0.1 0 0.12 0.10 0.08 0 1 2 3 4 SUPPLY VOLTAGE (V) 5 0.04 -55 6 -35 -15 5 25 45 65 TEMPERATURE (C) 85 105 115 Figure 13. Supply Current vs. Temperature 10 0 RAB = 10k -0.1 1 SUPPLY CURRENT (mA) -0.2 VDD = 5V -0.3 -0.4 VDD = 3V -0.5 -0.6 -0.7 VDD = 5V TA = 25C RAB = 10k ALL DIGITAL PINS TIED TOGETHER 0.1 VDD = 2.7V 0.01 03224-011 -0.9 -20 0 20 40 60 TEMPERATURE (C) 80 0.0001 100 Figure 11. Full-Scale Error 03224-014 0.001 -0.8 -1.0 -40 03224-013 0.06 03224-010 RHEOSTAT MODE LINEARITY (LSB) 80 0.16 TA = 25C RAB = 10k CODE = 0x20 Figure 10. RINL vs. Supply Voltage FSE (LSB) 20 40 60 TEMPERATURE (C) Figure 12. Zero-Scale Error 0.4 -0.1 0 -20 0 1 2 3 4 INPUT LOGIC VOLTAGE (V) 5 Figure 14. Supply Current vs. Digital Input Voltage Rev. H | Page 9 of 24 6 AD5273 VDD = 5.5V TA = 25C 400 0x3F 0 0x20 -6 0x10 300 1k MAGNITUDE (dB) -12 200 10k 100 0 50k -100 0x08 -18 0x04 -24 0x02 -30 0x01 -36 -42 0 16 8 24 32 40 CODE (Decimal) 48 56 03224-018 -300 0x00 100k -200 03224-015 RHEOSTAT MODE TEMPCO (ppm/C) 500 -48 -54 100 64 Figure 15. Rheostat Mode Tempco (RWB/RWB)/T vs. Code 1k 10k FREQUENCY (Hz) 100k 1M Figure 18. Gain vs. Frequency vs. Code, RAB = 10 k VDD = 5.5V 0x3F 0 30 1k 0x20 -6 10k 20 0x10 MAGNITUDE (dB) -12 10 0 -10 10k 10k 0x08 -18 0x04 -24 0x02 -30 0x01 -36 -20 0 8 16 24 32 40 CODE (Decimal) 48 -48 -54 100 64 56 0x3F MAGNITUDE (dB) -30 0x02 0x01 0x00 0x08 -18 0x04 -24 0x02 -30 0x01 -36 -42 -42 03224-017 MAGNITUDE (dB) 0x04 -24 -36 0x10 -12 0x08 -18 1M 0x20 -6 0x10 -12 100k 0x3F 0 0x20 -6 10k FREQUENCY (Hz) Figure 19. Gain vs. Frequency vs. Code, RAB = 50 k Figure 16. Potentiometer Mode Tempco (VW/VW)/T vs. Code 0 0x00 1k -48 -54 100 1k 10k 100k FREQUENCY (Hz) 1M 03224-020 -40 03224-019 -42 -30 03224-016 POTENTIOMETER MODE TEMPCO (ppm/C) 40 -48 -54 100 10M 0x00 1k 10k FREQUENCY (Hz) 100k Figure 20. Gain vs. Frequency vs. Code, RAB = 100 k Figure 17. Gain vs. Frequency vs. Code, RAB = 1 k Rev. H | Page 10 of 24 1M AD5273 12 1k 6 10k VDD = 5.5V VA = 5.5V VB = GND fCLK = 400kHz 0 MAGNITUDE (dB) -6 -12 DATA 0x00 0x3F VW = 5V/DIV 50k -18 100k -24 SCL = 5V/DIV -30 -42 -48 1k 100 10k 100k FREQUENCY (Hz) 1M 5V 5V 5s 10M Figure 21. -3 dB Bandwidth 03224-024 03224-021 -36 Figure 24. Large Settling Time TA = 25C CODE = 0x20 VA = 2.5V, VB = 0V VDD = 5.5V VA = 5.5V VB = GND fCLK = 100kHz DATA 0x20 0x1F -60 VDD = 5V DC 1.0V p-p AC -40 VDD = 3V DC 0.6V p-p AC VW = 50mV/DIV -20 03224-022 1k 10k FREQUENCY (Hz) 5V 1M 100k Figure 22. PSRR vs. Frequency Figure 25. Midscale Glitch Energy fCLK = 100kHz VDD = 5.5V VA = 5.5V VB = GND 200ns 03224-025 0 100 SCL = 5V/DIV 50mV OTP PROGRAMMED AT MS VDD = 5.5V VA = 5.5V RAB = 10k VW = 1V/DIV VW = 10mV/DIV w VDD = 5V/DIV 5V 500ns 03224-023 SCL = 5V/DIV 10mV 1V 5V 5s 03224-026 POWER SUPPLY REJECTION RATIO (dB) -80 Figure 26. Power-Up Settling Time After Fuses Blown Figure 23. Digital Feedthrough Rev. H | Page 11 of 24 AD5273 10 RAB = 1k RAB = 10k 1 RAB = 50k 0.1 RAB = 100k 0 8 16 24 32 40 CODE (Decimal) 48 56 64 03224-060 CH1 20.0mA M200ns A CH1 T 588.000ns t8 t9 t6 SCL t2 t4 t3 t8 t5 t7 t10 t9 t1 SDA P 32.4mA Figure 28. OTP Program Energy Plot for Single Fuse Figure 27. IWB_MAX vs. Code S P Figure 29. Interface Timing Diagram Rev. H | Page 12 of 24 03224-028 0.01 1 03224-027 THEORETICAL IWB_MAX (mA) VA = VB = OPEN TA = 25C AD5273 THEORY OF OPERATION The AD5273 is a one-time programmable (OTP), set-and-forget, 6-bit digital potentiometer. The AD5273 allows unlimited 6-bit adjustments prior to the OTP. OTP technology is a proven costeffective alternative over EEMEM in one-time memory programming applications. The AD5273 employs fuse link technology to achieve the memory retention of the resistance setting function. It comprises six data fuses, which control the address decoder for programming the RDAC, one user mode test fuse for checking setup error, and one programming lock fuse for disabling any further programming once the data fuses are programmed correctly. 5 V to 5.5 V for the 1 k (DD8) and 10 k (DD9) options, or from 4.75 V to 5.25 V for the 50 k (DYG) and 100 k (DYH) options. During operation, however, VDD can be 2.7 V to 5.5 V. Therefore, a system supply that is lower than VDD_OTP requires an external supply for OTP. The user is allowed only one attempt to blow the fuses. If the user fails to blow the fuses on the first attempt, the fuse structure may change such that they can never be blown, regardless of the energy applied during subsequent events. For details, see the Power Supply Considerations section. The device control circuit has two validation bits, E1 and E0, that can be read back in the read mode to check the programming status, as shown in Figure 32. Users should always read back the validation bits to ensure that the fuses are properly blown. After the fuses have been blown, all fuse latches are enabled upon subsequent power-on; therefore, the output corresponds to the stored setting. Figure 30 shows a detailed functional block diagram. ONE-TIME PROGRAMMING Prior to OTP activation, the AD5273 presets to midscale during power-on. After the wiper is set to the desired position, the resistance can be permanently set by programming the T bit and the one-time VDD_OTP to high and by coding the part properly (see Figure 31). To blow the fuses to achieve a given nonvolatile setting, the fuse link technology of the AD5273 requires a VDD_OTP from A SCL I2C INTERFACE SDA DECODER MUX DAC REG. W B COMPARATOR FUSES EN FUSE REG. 03224-031 ONE-TIME PROGRAM/TEST CONTROL BLOCK S 0 1 0 1 1 0 AD0 0 A T X SLAVE ADDRESS BYTE X X X X X X A X X D5 INSTRUCTION BYTE D4 D3 D2 D1 D0 A DATA BYTE P 03224-029 Figure 30. Detailed Functional Block Diagram S 0 1 0 1 1 0 AD0 1 A E1 E0 SLAVE ADDRESS BYTE D5 D4 D3 DATA BYTE D2 D1 D0 A P 03224-030 Figure 31. SDA Write Mode Bit Format Figure 32. SDA Read Mode Bit Format SDA Bit Definitions and Descriptions S = start condition. P = stop condition. A = acknowledge. X = don't care. T = OTP programming bit. Logic 1 programs wiper position permanently. D5, D4, D3, D2, D1, D0 = data bits. E1, E0 = OTP validation bits. 0, 0 = ready to program. 0, 1 = test fuse not blown successfully. (For factory setup checking purpose only. Users should not see these combinations.) 1, 0 = fatal error. Do not retry. Discard the unit. 1, 1 = programmed successfully. No further adjustments possible. AD0 = I2C device address bit. Allows maximum of two AD5273s to be addressed. Rev. H | Page 13 of 24 AD5273 The general equation for this operation is VARIABLE RESISTANCE AND VOLTAGE FOR RHEOSTAT MODE If only the W-to-B or W-to-A terminals are used as variable resistors, the unused A or B terminal can be opened or shorted with W. This operation is called rheostat mode (see Figure 33). B W B W B Figure 33. Rheostat Mode Configuration The nominal resistance, RAB, of the RDAC has 64 contact points accessed by the wiper terminal, plus the B terminal contact if RWB is considered. The 6-bit data in the RDAC latch is decoded to select one of the 64 settings. Assuming that a 10 k part is used, the wiper's first connection starts at Terminal B for Data Register 0x00. This connection yields a minimum of 60 resistance between Terminal W and Terminal B because of the 60 wiper contact resistance. The second connection is the first tap point, which corresponds to 219 (RW = 1 x RAB/63 + RW) for Data Register 0x01, and so on. Each LSB data value increase moves the wiper up the resistor ladder until the last tap point is reached at 10,060 (63 x RAB/63 + RW). Figure 34 shows a simplified diagram of the equivalent RDAC circuit. The general equation determining RWB is RWB (D ) = D x RAB + RW 63 Table 4. RWB vs. Codes; RAB = 10 k; Terminal A Opened D (Dec) 63 32 1 0 RWB () 10,060 5139 219 60 Table 5. RWA vs. Codes; RAB =10 k; Terminal B Opened D (Dec) 63 32 1 0 RWA () 60 4980 9901 10,060 Output State Full scale (RAB + RW) Midscale 1 LSB Zero scale (wiper contact resistance) Output State Full scale Midscale 1 LSB Zero scale The typical distribution of the resistance tolerance from device to device is process-lot dependent, and it is possible to have 30% tolerance. A D5 D4 D3 D2 D1 D0 RS RS W RS RDAC LATCH AND DECODER (1) where: D is the decimal equivalent of the 6-bit binary code. RAB is the end-to-end resistance. RW is the wiper resistance contributed by the on resistance of the internal switch. (2) B 03224-033 W A 63 - D x RAB + RW 63 Figure 34. AD5273 Equivalent RDAC Circuit VARIABLE RESISTANCE AND VOLTAGE FOR POTENTIOMETER MODE If all three terminals are used, the operation is called the potentiometer mode. The most common configuration is the voltage divider operation (see Figure 35). VI A W B Because a finite wiper resistance of 60 is present in the zeroscale condition, care should be taken to limit the current flow between W and B in this state to a maximum pulse current of 20 mA. Otherwise, degradation or possible destruction of the internal switch contact can occur. Similar to the mechanical potentiometer, the resistance of the RDAC between the Wiper W and Terminal A also produces a complementary resistance, RWA. When these terminals are used, Terminal B can be opened or shorted to W. Setting the resistance value for RWA starts at a maximum value of resistance and decreases as the data loaded in the latch increases in value. VO 03224-034 A 03224-032 A RWA ( D ) = Figure 35. Potentiometer Mode Configuration Ignoring the effect of the wiper resistance, the transfer function is simply VW (D ) = D VA 63 (3) A more accurate calculation, which includes the wiper resistance effect, yields Rev. H | Page 14 of 24 D RAB + RW 63 VW (D ) = VA RAB + 2RW (4) AD5273 Potentiometer mode includes op amp feedback resistor networks and other voltage scaling applications. Terminal A, Terminal W, and Terminal B can in fact be input or output terminals, provided that |VAB|, |VWA|, and |VWB| do not exceed VDD to GND. ESD PROTECTION Digital inputs SDA and SCL are protected with a series input resistor and parallel Zener ESD structures (see Figure 36). 340 03224-035 LOGIC Figure 36. ESD Protection of Digital Pins TERMINAL VOLTAGE OPERATING RANGE completing the fuse programming process. As a result, dual voltage supplies and isolation are needed if the system VDD is outside the required VDD_OTP range. For successful OTP, the fuse programming supply (either an on-board regulator or rack-mount power supply) must be rated at 5 V to 5.5 V for the 1 k (DD8) and 10 k (DD9) options, or at 4.75 V to 5.25 V for the 50 k (DYG) and 100 k (DYH) options, and be capable of sourcing 100 mA for 400 ms. When fuse programming is completed, the VDD_OTP supply can be removed to allow normal operation of 2.7 V to 5.5 V; the device then reduces the current consumption to the A range. When operating systems at 2.7 V, use of the bidirectional low threshold P-Ch MOSFETs is recommended for the supply's isolation. As shown in Figure 38, this assumes that the 2.7 V system voltage is applied first and that the P1 and P2 gates are pulled to ground, thus turning on P1 first and then P2. As a result, VDD of the AD5273 approaches 2.7 V. When the AD5273 setting is found, the factory tester applies the VDD_OTP to both the VDD and the MOSFETs' gates, thus turning off P1 and P2. The OTP command should be executed at this time to program the AD5273 while the 2.7 V source is protected. Once the fuse programming is complete, the tester withdraws the VDD_OTP and the AD5273's setting is fixed permanently. There are also ESD protection diodes between VDD and the RDAC terminals. The VDD of AD5273 therefore defines their voltage boundary conditions (see Figure 37). Supply signals present on Terminal A, Terminal B, and Terminal W that exceed VDD are clamped by the internal forward-biased diodes. VDD_OTP APPLIES FOR OTP ONLY R1 10k 2.7V VDD P1 P2 C1 10mF A W P1 = P2 = FDV302P, NDS0610 VDD AD5273 Figure 38. OTP Supply Isolated from the 2.7 V Normal Operating Supply 03224-036 B GND C2 0.1F 03224-039 Unlike rheostat mode where the absolute tolerance is high, potentiometer mode yields an almost ratiometric function of D/63 with a relatively small error contributed by the RW terms. Therefore, the tolerance effect is almost cancelled. Although the step resistor, RS, and CMOS switch resistor, RW, have very different temperature coefficients, the ratiometric adjustment also reduces the overall temperature coefficient effect to 5 ppm/C, except at low value codes where RW dominates. Figure 37. Maximum Terminal Voltages Set by VDD POWER-UP/POWER-DOWN SEQUENCES Because of the ESD protection diodes, it is important to power VDD first before applying any voltages to Terminal A, Terminal B, and Terminal W. Otherwise, the diode is forward-biased such that VDD is powered unintentionally and can affect the rest of the user's circuits. The ideal power-up sequence is in the following order: GND, VDD, digital inputs, and VA/VB/VW. The order of powering VA, VB, VW, and digital inputs is not important as long as they are powered after VDD. Similarly, VDD should be powered down last. POWER SUPPLY CONSIDERATIONS To minimize the package pin count, both OTP and normal operating voltage supplies are applied to the same VDD terminal of the AD5273. The AD5273 employs fuse link technology that requires from 5 V to 5.5 V for the 1 k (DD8) and 10 k (DD9) options, or from 4.75 V to 5.25 V for the 50 k (DYG) and 100 k (DYH) options, for blowing the internal fuses to achieve a given setting, but normal VDD can be in the range of 2.7 V to 5.5 V after The AD5273 achieves the OTP function through blowing internal fuses. Users should always apply the recommended OTP programming voltage at the first fuse programming attempt. Failure to comply with this requirement can lead to a change in fuse structures, rendering programming inoperable. Care should be taken when SCL and SDA are driven from a low voltage logic controller. Users must ensure that the logic high level is between 0.7 x VDD and VDD. Refer to the Level Shift for Different Voltages Operation section. Poor PCB layout introduces parasitics that can affect fuse programming. Therefore, it is recommended to add a 10 F tantalum capacitor in parallel with a 1 nF ceramic capacitor as close as possible to the VDD pin. The type and value chosen for both capacitors are important. This combination of capacitor values provides a fast response and larger supply current handling with minimum supply drop during transients. As a result, these capacitors increase the OTP programming success by not inhibiting the proper energy needed to blow the internal fuses. Additionally, C1 minimizes transient disturbance and low frequency ripple, while C2 reduces high frequency noise during normal operation. Rev. H | Page 15 of 24 AD5273 CONTROLLING THE AD5273 To apply the device programming software in the factory, lay out the AD5273 SCL and SDA pads on the PCB such that the programming signals can be communicated to and from the parallel port (see Figure 40). Figure 41 shows a recommended AD5273 PCB layout into which pogo pins can be inserted for factory programming. To prevent damaging the PC parallel port, 100 resistors should also be put in series to the SCL and SDA pins. Pull-up resistors on SCL and SDA are also required. 03224-040 Because of the OTP feature, users can program the AD5273 in the factory before shipping it to end users. Therefore, Analog Devices offers device programming software that can be implemented in the factory on computers running Windows NT, Windows 2000, and Windows XP platforms. The software, which can be downloaded from the AD5273 product page at www.analog.com, is an executable file that does not require any programming languages or user programming skills. Figure 39 shows the software interface. Figure 39. Software Interface Write The AD5273 starts at midscale after power-up prior to any OTP programming. To increment or decrement the resistance, move the scrollbar on the left. Once the desired setting is found, click Program Permanent to lock the setting permanently. To write any specific values, use the bit pattern control in the upper section and click Run. The format of writing data to the device is shown in Figure 31. Once the desired setting is found, set the T bit to 1 and click Run to program the setting permanently. Read To read the validation bits and data from the device, click Read. The user can also set the bit pattern in the upper section and click Run. The format of reading data from the device is shown in Figure 32. Rev. H | Page 16 of 24 13 25 12 24 11 23 10 22 9 21 8 20 7 19 6 18 5 17 4 16 3 15 2 14 1 VDD R3 100 R4 10k R5 10k SCL SDA R2 READ 100 R1 WRITE 100 03224-041 SOFTWARE PROGRAMMING To control the device in both read and write operations, the program generates the I2C digital signals through the parallel port LPT1 Pin 2, Pin 3, Pin 15, and Pin 25 for SDA_write, SCL, SDA_read, and DGND, respectively (see Figure 40). Figure 40. Parallel Port Connection; Pin 2 = SDA_Write, Pin 3 = SCL, Pin 15 = SDA_Read, and Pin 25 = DGND W VDD GND SCL A B AD0 SDA 03224-042 To control the AD5273, users can program the device with either computer software or with external I2C controllers. Figure 41. Recommended AD5273 PCB Layout AD5273 I2C CONTROLLER PROGRAMMING Write Bit Patterns 0 8 8 0 0 8 SCL 1 0 1 0 1 0 AD0 R/W X X X X X X X ACK. BY AD5273 FRAME 1 SLAVE ADDRESS BYTE START BY MASTER X X D5 D4 D3 D2 D1 D0 ACK. BY AD5273 ACK. BY AD5273 FRAME 2 INSTRUCTION BYTE FRAME 1 DATA BYTE STOP BY MASTER 03224-043 0 STOP BY MASTER 03224-044 SDA Figure 42. Writing to the RDAC Register 0 8 8 0 0 8 SCL SDA 0 1 0 1 0 1 AD0 R/W 1 X X X X X X START BY MASTER X X X ACK. BY AD5273 D5 D4 D3 D2 D1 D0 ACK. BY AD5273 FRAME 1 SLAVE ADDRESS BYTE ACK. BY AD5273 FRAME 2 INSTRUCTION BYTE FRAME 1 DATA BYTE Figure 43. Activating One-Time Programming Read Bit Pattern 8 0 0 8 SCL 0 1 0 1 1 0 AD0 R/W E1 ACK. BY AD5273 START BY MASTER FRAME 1 SLAVE ADDRESS BYTE E0 D5 D4 D3 D2 D1 D0 NO ACK. BY AD5273 FRAME 2 DATA BYTE FROM SELECTED RDAC REGISTER STOP BY MASTER 03224-059 SDA Figure 44. Reading Data from the RDAC Register For users who do not use the software solution, the AD5273 can be controlled via an I2C-compatible serial bus and is connected to this bus as a slave device. Referring to Figure 42, Figure 43, and Figure 44, the 2-wire I2C serial bus protocol operates as follows: 1. The master initiates data transfer by establishing a start condition. A start condition is defined as a high-to-low transition on the SDA line while SCL is high, as shown in Figure 42. The byte following the start condition is the slave address byte, which consists of six MSBs defined as 010110. The next bit is AD0; it is an I2C device address bit. Depending on the states of the AD0 bits, two AD5273s can be addressed on the same bus, as shown in Figure 45. The last LSB is the R/W bit, which determines whether data is read from or written to the slave device. 2. A write operation contains one more instruction byte than the read operation. The instruction byte in the write mode follows the slave address byte. The MSB of the instruction byte labeled T is the OTP bit. After acknowledging the instruction byte, the last byte in the write mode is the data byte. Data is transmitted over the serial bus in sequences of nine clock pulses (eight data bits followed by an acknowledge bit). The transitions on the SDA line must occur during the low period of SCL and remain stable during the high period of SCL, as shown in Figure 42. 3. In read mode, the data byte follows immediately after the acknowledgment of the slave address byte. Data is transmitted over the serial bus in sequences of nine clock pulses (slight difference from write mode, there are eight data bits followed by a no acknowledge bit). Similarly, the transitions on the SDA line must occur during the low period of SCL and remain stable during the high period of SCL, as shown in Figure 44. The slave address corresponding to the transmitted address responds by pulling the SDA line low during the ninth clock pulse (this is termed the acknowledge bit). At this stage, all other devices on the bus remain idle while the selected device waits for data to be written to or read from its serial register. Rev. H | Page 17 of 24 AD5273 When all data bits have been read or written, a stop condition is established by the master. A stop condition is defined as a low-to-high transition on the SDA line while SCL is high. In write mode, the master pulls the SDA line high during the 10th clock pulse to establish a stop condition, as shown in Figure 42 and Figure 43. In read mode, the master issues a no acknowledge for the ninth clock pulse, that is, the SDA line remains high. The master then brings the SDA line low before the 10th clock pulse, which goes high to establish a stop condition, as shown in Figure 44. CONTROLLING TWO DEVICES ON ONE BUS Figure 45 shows two AD5273 devices on the same serial bus. Each has a different slave address because the state of each AD0 pin is different. This allows each device to operate independently. The master device output bus line drivers are open-drain pulldown in a fully I2C-compatible interface. A repeated write function gives the user flexibility to update the RDAC output continuously, except after permanent programming, when the part is addressed and receives instructions only once. During the write cycle, each data byte updates the RDAC output. For example, after the RDAC has acknowledged its slave address and instruction bytes, the RDAC output updates after these two bytes. If another byte is written to the RDAC while it is still addressed to a specific slave device with the same instruction, this byte updates the output of the selected slave device. If different instructions are needed, the write mode must be started again with a new slave address, instruction, and data bytes. Similarly, a repeated read function of the RDAC is also allowed. Rev. H | Page 18 of 24 5V RP RP SDA MASTER SCL SDA SCL AD0 AD5273 5V SDA SCL AD0 AD5273 Figure 45. Two AD5273 Devices on One Bus 03224-045 4. AD5273 APPLICATIONS INFORMATION 5V DAC It is common to buffer the output of the digital potentiometer as a DAC. The buffer minimizes the load dependence and delivers higher current to the load, if needed. 2 AD5273 VOUT 3 A W U2 03224-046 IL = SIGNAL (VREF x D )/ 64 | 32 D 63 (5) RS GAIN CONTROL COMPENSATION As shown in Figure 49, the digital potentiometers are commonly used in gain controls or sensor transimpedance amplifier signal conditioning applications. C2 4.7pF RBIAS IL R2 B 100k A AD8601 LD -V 03224-047 B U2 100 IL Figure 48. Programmable Current Source VOUT CC RL -5V U3 2N7002 VIN VL V- -2.048 + V L For applications that require high current adjustment, such as a laser diode driver or tunable laser, consider a booster voltage source, as shown in Figure 47. W 102 +5V OP1177 PROGRAMMABLE VOLTAGE SOURCE WITH BOOSTED OUTPUT A RS V+ VO AD8601 Figure 46. Programmable Voltage Reference (DAC) +V A U2 ADR03 U1 W 1F 4 GND AD5273 C1 GND 5V B U3 AD5273 03224-048 U1 B 2 6 REF191 U3 VIN 0V TO ... OUPUT 3 SLEEP 5V 1 U1 VS R1 47k W Figure 47. Programmable Booster Voltage Source U1 In this circuit, the inverting input of the op amp forces the VOUT to be equal to the wiper voltage set by the digital potentiometer. The load current is then delivered by the supply via the N-Channel FET, N1. N1 power handling must be adequate to dissipate (VIN - VOUT) x IL power. This circuit can source a maximum of 100 mA with a 5 V supply. For precision applications, a voltage reference, such as the ADR421, ADR03, or ADR370, can be applied at Terminal A of the digital potentiometer. PROGRAMMABLE CURRENT SOURCE A programmable current source can be implemented with the circuit shown in Figure 48. The load current is the voltage across Terminal B to Terminal W of the AD5273 divided by RS. At zero scale, Terminal A of the AD5273 is -2.048 V, which makes the wiper voltage clamped at ground potential. Depending on the load, Equation 5 is therefore valid only at certain codes. For example, when the compliance voltage, VL, equals half of VREF, the current can be programmed from midscale to full scale of the AD5273. VO VI 03224-049 C1 Figure 49. Typical Noninverting Gain Amplifier In both applications, one of the digital potentiometer terminals is connected to the op amp inverting node with finite terminal capacitance, C1. It introduces a zero for the 1 o term with 20 dB/dec, whereas a typical op amp GBP has -20 dB/dec characteristics. A large R2 and finite C1 can cause this zero's frequency to fall well below the crossover frequency. Therefore, the rate of closure becomes 40 dB/dec and the system has a 0 phase margin at the crossover frequency. The output may ring, or in the worst case, oscillate when the input is a step function. Similarly, it is also likely to ring when switching between two gain values because this is equivalent to a step change at the input. To reduce the effect of C1, users should also configure Terminal B or Terminal A rather than Terminal W at the inverting node. Rev. H | Page 19 of 24 AD5273 PROGRAMMABLE LOW-PASS FILTER VO O 2 = VI S 2 + O S + O 2 Q Q= VDD2 = 5V VDD1 = 2.5V Rp (6) 1 R1R2C1C2 (7) 1 1 + R1C1 R2C2 (8) SDA1 C +2.5V B A C AD8601 B W C2 SCL2 M2 2.7V-5.5V 2.5V CONTROLLER AD5273 Figure 51. Level Shift for Different Voltages Operation RDAC CIRCUIT SIMULATION MODEL The internal parasitic capacitances and the external capacitive loads dominate the ac characteristics of the digital potentiometers. Configured as a potentiometer divider, the -3 dB bandwidth of the AD5273 (1 k resistor) measures 6 MHz at half scale. Figure 17 to Figure 20 provide the large signal BODE plot characteristics of the four available resistor versions: 1 k, 10 k, 50 k, and 100 k. Figure 52 shows a parasitic simulation model. The code following Figure 52 provides a macro model net list for the 1 k device. A B 1k CW CA 25pF 55pF W .PARAM D = 63, RDAC = 1E3 V+ V- ADJUSTED TO SAME SETTINGS SDA2 D S M1 Macro Model Net List for RDAC R2 W G D CB 25pF Figure 52. Circuit Simulation Model for RDAC = 1 k U1 -2.5V Figure 50. Sallen Key Low-Pass Filter VO 03224-050 VI Rp G C1 R1 Rp S Users can first select some convenient values for the capacitors. To achieve maximally flat bandwidth where Q = 0.707, let C1 be twice the size of C2 and let R1 = R2. As a result, R1 and R2 can be adjusted to the same setting to achieve the desired bandwidth. A Rp SCL1 In ADC applications, it is common to include an antialiasing filter to band-limit the sampling signal. To minimize various system redesigns, users can use two 1 k AD5273s to construct a generic second-order Sallen-Key low-pass filter. Because the AD5273 is a single-supply device, the input must be dc offset when an ac signal is applied to avoid clipping at ground. This is illustrated in Figure 50. The design equations are O = If the SCL and SDA signals come from a low voltage logic controller and are below the minimum VIH level (0.7 x VDD), level-shift the signals for successful read/write communication between the AD5273 and the controller. Figure 51 shows one of the implementations. For example, when SDA1 is 2.5 V, M1 turns off, and SDA2 becomes 5 V. When SDA1 is 0 V, M1 turns on, and SDA2 approaches 0 V. As a result, proper level-shifting is established. M1 and M2 should be low threshold N-Channel power MOSFETs, such as FDV301N. 03224-051 There is also a Terminal W capacitance connected to the output (not shown); its effect on stability is less significant; therefore, compensation is not necessary unless the op amp is driving a large capacitive load. LEVEL SHIFT FOR DIFFERENT VOLTAGES OPERATION 03224-055 Depending on the op amp GBP, reducing the feedback resistor may extend the zero's frequency far enough to overcome the problem. A better approach is to include a compensation capacitor, C2, to cancel the effect caused by C1. Optimum compensation occurs when R1 x C1 = R2 x C2, but this is not an option because of the variation of R2. As a result, users can use the relationship described and scale C2 as if R2 were at its maximum value. However, doing so may overcompensate by slowing down the settling time when R2 is set to low values. To avoid this problem, C2 should be found empirically for a given application. In general, setting C2 in the range of a few picofarads to no more than a few tenths of a picofarad is usually adequate for compensation. * .SUBCKT DPOT (A,W,B) * CA A 0 25E-12 RWA A W {(1-D/63)*RDAC+60} CW W 0 55E-12 RWB W B {D/63*RDAC+60} CB B 0 25E-12 * .ENDS DPOT Rev. H | Page 20 of 24 AD5273 EVALUATION BOARD JP5 VCC JP3 V+ VDD C4 0.1F -IN1 CP3 VREF C5 0.1F ADR03 CP4 -IN1 CP2 CP1 JP1 2 A JP8 JP7 W VIN 8 OUT1 1 3 4 U3A CP6 OUT1 B VDD JP2 C1 10mF J1 8 7 6 5 4 3 2 1 R1 10k U1 1 A 2 W B V 3 DD GND AD0 4 SCL SDA R2 10k C2 0.1F SCL 8 7 6 5 U2 1 A 2 W B V 3 DD GND AD0 4 SCL SDA C3 0.1F AD5170 8 7 6 5 C7 10F V- +IN1 CP7 CP5 AGND JP4 C8 0.1F C9 10F AD5171/AD5273 SDA JP6 -IN2 +IN2 6 7 OUT2 5 U3B VEE 03224-056 VDD C6 0.1F U4 5 1 TEMP TRIM 2 GND 3 V 4 VOUT IN Figure 53. Evaluation Board Schematic CP2 VDD VREF 2 JP3 4 U3A 1 V+ V- 3 11 VREF JP1 VO A U2 B JP7 W OUT1 AD822 JP4 JP2 03224-058 W 03224-057 A B Figure 55. Evaluation Board Figure 54. One Possible Configuration-- Programmable Voltage Reference Rev. H | Page 21 of 24 AD5273 OUTLINE DIMENSIONS 3.00 2.90 2.80 1.70 1.60 1.50 8 7 6 5 1 2 3 4 3.00 2.80 2.60 PIN 1 INDICATOR 0.65 BSC 1.95 BSC 1.45 MAX 0.95 MIN 0.15 MAX 0.05 MIN 0.38 MAX 0.22 MIN 0.22 MAX 0.08 MIN SEATING PLANE 8 4 0 0.60 BSC 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-BA 121608-A 1.30 1.15 0.90 Figure 56. 8-Lead Small Outline Transistor Package [SOT-23] (RJ-8) Dimensions shown in millimeters ORDERING GUIDE Model 1, 2 AD5273BRJZ1-R2 AD5273BRJZ1-REEL7 AD5273BRJZ10-R2 AD5273BRJZ10-R7 AD5273BRJZ50-REEL7 AD5273BRJZ100-R2 AD5273BRJZ100-R7 AD5273EVAL 1 2 RAB (k) 1 1 10 10 50 100 100 Temperature Range -40C to +105C -40C to +105C -40C to +105C -40C to +105C -40C to +105C -40C to +105C -40C to +105C Package Option RJ-8 RJ-8 RJ-8 RJ-8 RJ-8 RJ-8 RJ-8 Package Description 8-Lead SOT-23 8-Lead SOT-23 8-Lead SOT-23 8-Lead SOT-23 8-Lead SOT-23 8-Lead SOT-23 8-Lead SOT-23 Evaluation Board Ordering Quantity 250 3,000 250 3,000 3,000 250 3,000 Z = RoHS Compliant Part. For the evaluation board, users should order samples because the evaluation kit comes with a socket, but does not include the parts. Rev. H | Page 22 of 24 Branding DD8 DD8 DD9 DD9 DYG DYH DYH AD5273 NOTES Rev. H | Page 23 of 24 AD5273 NOTES I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors). (c)2002-2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D03224-0-10/10(H) Rev. H | Page 24 of 24