19-3478; Rev 1; 1/05 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers The MAX5487/MAX5488/MAX5489 dual, linear-taper, digital potentiometers function as mechanical potentiometers with a simple 3-wire SPI™-compatible digital interface that programs the wipers to any one of 256 tap positions. These digital potentiometers feature a nonvolatile memory (EEPROM) to return the wipers to their previously stored positions upon power-up. The MAX5487 has an end-to-end resistance of 10kΩ, while the MAX5488 and MAX5489 have resistances of 50kΩ and 100kΩ, respectively. These devices have a low 35ppm/°C end-to-end temperature coefficient, and operate from a single +2.7V to +5.25V supply. The MAX5487/MAX5488/MAX5489 are available in a 16-pin 3mm x 3mm x 0.8mm thin QFN package. Each device is guaranteed over the extended -40°C to +85°C temperature range. Features ♦ Wiper Position Stored in Nonvolatile Memory (EEPROM) and Recalled Upon Power-Up or Recalled by an Interface Command ♦ 3mm x 3mm x 0.8mm Thin QFN Package ♦ ±1 LSB INL, ±0.5 LSB DNL (Voltage-Divider Mode) ♦ 256 Tap Positions ♦ 35ppm/°C End-to-End Resistance Temperature Coefficient ♦ 5ppm/°C Ratiometric Temperature Coefficient ♦ 10kΩ, 50kΩ, and 100kΩ End-to-End Resistance Values ♦ SPI-Compatible Serial Interface LCD Screen Adjustment ♦ Reliability 200,000 Wiper Store Cycles 50-Year Wiper Data Retention Audio Volume Control ♦ +2.7V to +5.25V Single-Supply Operation Applications Mechanical Potentiometer Replacement Low-Drift Programmable Filters SPI is a trademark of Motorola, Inc. Low-Drift Programmable-Gain Amplifiers Ordering Information/Selector Guide PART TEMP RANGE PIN-PACKAGE END-TO-END RESISTANCE (kΩ) TOP MARK MAX5487ETE* -40°C to +85°C 16 Thin QFN-EP** 10 ABR MAX5488ETE -40°C to +85°C 16 Thin QFN-EP** 50 ABS MAX5489ETE -40°C to +85°C 16 Thin QFN-EP** 100 ABT *Future product—contact factory for availability. **EP = Exposed pad. Functional Diagram WA LA VDD 1 SCLK 2 DIN 3 CS 4 HA WA LA 12 HB HB CS 8-BIT LATCH 256 8 DECODER 10 LB 9 N.C. WB 5 MAX5487 MAX5488 MAX5489 11 WB MAX5487 MAX5488 MAX5489 POR LB 6 7 8 N.C. 16-BIT NV RAM 13 GND SPI INTERFACE 14 N.C. DECODER SCLK DIN 15 N.C. GND 16 256 8 8-BIT LATCH TOP VIEW N.C. HA VDD Pin Configuration THIN QFN 3mm × 3mm EXPOSED PAD CONNECTED TO GND. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX5487/MAX5488/MAX5489 General Description MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers ABSOLUTE MAXIMUM RATINGS VDD to GND ...........................................................-0.3V to +6.0V All Other Pins to GND......................-0.3V to the lower of (VDD + 0.3V) and +6.0V Maximum Continuous Current into H_, W_, and L_ MAX5487......................................................................±5.0mA MAX5488......................................................................±1.3mA MAX5489......................................................................±0.6mA Continuous Power Dissipation (TA = +70°C) 16-Pin Thin QFN (derate 17.5mW/°C above +70°C).....1398mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC PERFORMANCE (Voltage-Divider Mode, Figure 1) Resolution N 256 Taps Integral Nonlinearity INL (Note 2) ±1 LSB Differential Nonlinearity DNL (Note 2) ±0.5 LSB 2 LSB Dual-Code Matching End-To-End Resistor Tempco Register A = register B TCR Ratiometric Resistor Tempco Full-Scale Error Zero-Scale Error 35 ppm/°C 5 ppm/°C MAX5488 -0.6 +1.2 MAX5489 -0.3 +1.2 MAX5488 0.6 1.5 MAX5489 0.3 1 LSB LSB DC PERFORMANCE (Variable-Resistor Mode, Figure 1) Resolution 256 Integral Nonlinearity (Note 3) MAX5488/MAX5489 Differential Nonlinearity (Note 3) MAX5488/MAX5489 Taps VDD = 5.0V ±1.5 VDD = 3.0V ±3 VDD = 5.0V ±1 VDD = 3.0V ±1 LSB DC PERFORMANCE (Resistor Characteristics) Wiper Resistance (Note 4) RW Wiper Capacitance CW End-to-End Resistance 2 RHL VDD = 5.0V 200 350 VDD = 3.0V 325 675 50 MAX5487 7.5 MAX5488 MAX5489 pF 10 12.5 37.5 50 62.5 75 100 125 _______________________________________________________________________________________ Ω kΩ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers (VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DIGITAL INPUTS Input High Voltage (Note 5) VIH Input Low Voltage VIL Input Leakage Current IIN Input Capacitance CIN VDD = 3.6V to 5.25V 2.4 VDD = 2.7V to 3.6V 0.7 x VDD V VDD = 2.7V to 5.25V (Note 5) 0.8 V ±1.0 µA 5.0 pF -90 dB AC PERFORMANCE fH_ = 1kHz, L_ = GND, measurement at W_ (Note 6) Crosstalk MAX5488 90 MAX5489 45 -3dB Bandwidth BW Wiper at midscale CW_ = 10pF Total Harmonic Distortion THD VH_ = 1VRMS at 1kHz, L_ = GND, measurement at W_ kHz 0.02 % TIMING CHARACTERISTICS (Analog) Wiper-Settling Time tS Code 0 to 127 (Note 7) MAX5488 0.75 MAX5489 1.5 µs TIMING CHARACTERISTICS (Digital, Figure 2, Note 8) SCLK Frequency 5 MHz SCLK Clock Period tCP 200 ns SCLK Pulse-Width High tCH 80 ns ns SCLK Pulse-Width Low tCL 80 CS Fall to SCLK Rise Setup tCSS 80 ns SCLK Rise to CS Rise Hold tCSH 0 ns DIN to SCLK Setup tDS 50 ns DIN Hold after SCLK tDH 0 ns SCLK Rise to CS Fall Delay tCS0 20 ns CS Rise to SCLK Rise Hold tCS1 80 ns CS Pulse-Width High tCSW 200 ns Write NV Register Busy Time tBUSY 12 ms Read NV Register Access Time tACC 1 µs Write Wiper Register to Output Delay tWO 1 µs NONVOLATILE MEMORY RELIABILITY Data Retention Mil-Std-883 test method 1008 TA = +85°C 50 TA = +125°C 10 Endurance Mil-Std-883 test method 1033 TA = +85°C 200,000 TA = +125°C 50,000 Years Stores _______________________________________________________________________________________ 3 MAX5487/MAX5488/MAX5489 DC ELECTRICAL CHARACTERISTICS (continued) MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers DC ELECTRICAL CHARACTERISTICS (continued) (VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.25 V 400 µA 1 µA POWER SUPPLIES Power-Supply Voltage VDD Supply Current IDD Standby Current 2.70 During write cycle only, digital inputs = VDD or GND Digital inputs = VDD or GND, TA = +25°C 0.5 Note 1: All devices are production tested at TA = +25°C and are guaranteed by design and characterization for -40°C < TA < +85°C. Note 2: DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = VDD and L_ = 0. The wiper terminal is unloaded and measured with an ideal voltmeter. Note 3: DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = 0. For VDD = +5V, the wiper terminal is driven with a source current of 400µA for the 10kΩ configuration, 80µA for the 50kΩ configuration, and 40µA for the 100kΩ configuration. For VDD = +3V, the wiper terminal is driven with a source current of 200µA for the 10kΩ configuration, 40µA for the 50kΩ configuration, and 20µA for the 100kΩ configuration. Note 4: The wiper resistance is the worst value measured by injecting the currents given in Note 3 into W_ with L_ = GND. RW = (VW - VH) / IW. Note 5: The device draws higher supply current when the digital inputs are driven with voltages between (VDD - 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics section. Note 6: Wiper at midscale with a 10pF load. Note 7: Wiper-settling time is the worst-case 0-to-50% rise time, measured between tap 0 and tap 127. H_ = VDD, L_ = GND, and the wiper terminal is unloaded and measured with a 10pF oscilloscope probe (see Tap-to-Tap Switching Transient in the Typical Operating Characteristics section). Note 8: Digital timing is guaranteed by design and characterization, and is not production tested. VOLTAGE-DIVIDER CONFIGURATION H VARIABLE-RESISTOR CONFIGURATION H W L L Figure 1. Voltage-Divider/Variable-Resistor Configurations 4 _______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers VCC = 5V 0.4 VCC = 5V 100 10 VCC = 3V MAX5487-89toc03 400 WIPER RESISTANCE (Ω) 0.8 0.6 1000 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 1.0 10,000 MAX5487-89 toc02 MAX5487-89 toc01 1.2 WIPER RESISTANCE vs. TAP POSITION (MAX5488) SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 300 200 100 1 0.2 VCC = 3V 0 0 0 -40 -15 10 35 60 85 0 1 2 3 4 TEMPERATURE (°C) DIGITAL INPUT VOLTAGE (V) TAP-TO-TAP SWITCHING TRANSIENT (MAX5488) TAP-TO-TAP SWITCHING TRANSIENT (MAX5489) 0 5 64 96 128 160 192 224 256 TAP POSITION WIPER TRANSIENT AT POWER-ON MAX5487-89 toc06 MAX5487-89 toc05 MAX5487-89 toc04 VH_ = VDD VH_ = 5.0V VH_ = 5.0V CS 2.0V/div CS 2.0V/div VDD 2.0V/div WIPER 20mV/div WIPER 20mV/div WIPER 2.0V/div 1.0µs/div 32 1.0µs/div 2.0µs/div _______________________________________________________________________________________ 5 MAX5487/MAX5488/MAX5489 Typical Operating Characteristics (VDD = +5.0V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = +5.0V, TA = +25°C, unless otherwise noted.) MIDSCALE FREQUENCY RESPONSE (MAX5488) MIDSCALE FREQUENCY RESPONSE (MAX5489) -15 CW_ = 50pF -20 -25 -30 -30 -40 -40 -45 -45 -50 -50 1 10 100 1000 MAx5487-89 toc09 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 0.1 1 10 100 1000 0 32 64 96 128 160 192 224 256 FREQUENCY (kHz) TAP POSITION VARIABLE-RESISTOR INL vs. TAP POSITION (MAX5488) VOLTAGE-DIVIDER DNL vs. TAP POSITION (MAX5488) VOLTAGE-DIVIDER INL vs. TAP POSITION (MAX5488) 0.10 0.4 DNL (LSB) 0.2 0 -0.2 0 -0.8 -0.15 -1.0 -0.20 32 64 96 128 160 192 224 256 TAP POSITION 0.6 0.2 0 -0.2 -0.4 -0.10 -0.6 0.8 0.4 0.05 -0.05 -0.4 MAx5487-89 toc12 0.15 INL (LSB) 0.6 1.0 MAx5487-89 toc11 0.20 MAx5487-89 toc10 0.8 0 0.15 FREQUENCY (kHz) 1.0 6 -25 -35 0.20 CW_ = 50pF -20 -35 0.1 CW_ = 10pF -10 GAIN (dB) GAIN (dB) -15 0 -5 DNL (LSB) -10 VARIABLE-RESISTOR DNL vs. TAP POSITION (MAX5488) MAX5487-89 toc08 CW_ = 10pF MAX5487-89 toc07 0 -5 INL (LSB) MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers -0.6 -0.8 -1.0 0 32 64 96 128 160 192 224 256 TAP POSITION 0 32 64 96 128 160 192 224 256 TAP POSITION _______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers VARIABLE-RESISTOR INL vs. TAP POSITION (MAX5489) 0.10 0.20 MAx5487-89 toc14 0.15 0.8 0.6 0.15 0.10 0.4 0 -0.05 0.2 DNL (LSB) INL (LSB) 0.05 0 -0.2 -0.15 -0.8 -1.0 -0.20 -0.20 0 128 160 192 224 256 96 32 64 96 128 160 192 224 256 0 32 64 TAP POSITION VOLTAGE-DIVIDER INL vs. TAP POSITION (MAX5489) CROSSTALK vs. FREQUENCY -30 MAx5487-89 toc16 1.0 0.8 0.6 128 160 192 224 256 96 TAP POSITION TAP POSITION CW_ = 10pF -40 CROSSTALK (dB) 0.4 0.2 0 -0.2 MAX5487-89toc17 64 -0.4 -50 MAX5489 -60 -70 -80 -0.6 MAX5488 -90 -0.8 -100 -1.0 32 64 96 0.1 128 160 192 224 256 1 100 10 1000 TAP POSITION FREQUENCY (kHz) END-TO-END RESISTANCE CHANGE vs. TEMPERATURE (MAX5488) END-TO-END RESISTANCE CHANGE vs. TEMPERATURE (MAX5489) 0.008 0.006 0.004 0.002 0 -0.002 -0.004 0.010 MAX5487-89 toc19 0.010 0.008 RESISTANCE CHANGE (%) 0 MAX5487-89 toc18 32 INL (LSB) 0 0 -0.10 -0.6 -0.15 0.05 -0.05 -0.4 -0.10 RESISTANCE CHANGE (%) DNL (LSB) 1.0 MAx5487-89 toc13 0.20 VOLTAGE-DIVIDER DNL vs. TAP POSITION (MAX5489) MAx5487-89 toc15 VARIABLE-RESISTOR DNL vs. TAP POSITION (MAX5489) 0.006 0.004 0.002 0 -0.002 -0.004 -0.006 -0.006 -0.008 -0.008 -0.010 -0.010 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 7 MAX5487/MAX5488/MAX5489 Typical Operating Characteristics (continued) (VDD = +5.0V, TA = +25°C, unless otherwise noted.) Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489 Pin Description PIN NAME FUNCTION 1 VDD 2 SCLK Serial-Interface Clock Input 3 DIN Serial-Interface Data Input 4 CS Active-Low Chip-Select Digital Input 5, 6, 8, 9, 16 N.C. No Connection. Not internally connected. 7 GND Ground 10 LB Low Terminal of Resistor B. The voltage at L can be greater than or less than the voltage at H. Current can flow into or out of L. 11 WB Wiper Terminal of Resistor B 12 HB High Terminal of Resistor B. The voltage at H can be greater than or less than the voltage at L. Current can flow into or out of H. 13 LA Low Terminal of Resistor A. The voltage at L can be greater than or less than the voltage at H. Current can flow into or out of L. 14 WA Wiper Terminal of Resistor A 15 HA High Terminal of Resistor A. The voltage at H can be greater than or less than the voltage at L. Current can flow into or out of H. — E.P. Exposed Pad. Not internally connected. Connect to ground or leave floating. Power Supply. Bypass to GND with a 0.1µF capacitor as close to the device as possible. Detailed Description The MAX5487/MAX5488/MAX5489 contain two resistor arrays, with 255 resistive elements each. The MAX5487 has an end-to-end resistance of 10kΩ, while the MAX5488 and MAX5489 have resistances of 50kΩ and 100kΩ, respectively. The MAX5487/MAX5488/MAX5489 allow access to the high, low, and wiper terminals on both potentiometers for a standard voltage-divider configuration. Connect the wiper to the high terminal, and connect the low terminal to ground, to make the device a variable resistor (see Figure 1). A simple 3-wire serial interface programs either wiper directly to any of the 256 tap points. The nonvolatile memory stores the wiper position prior to power-down and recalls the wiper to the same point upon power-up or by using an interface command (see Table 1). The nonvolatile memory is guaranteed for 200,000 wiper store cycles and 50 years for wiper data retention. SPI Digital Interface The MAX5487/MAX5488/MAX5489 use a 3-wire SPIcompatible serial data interface (Figures 2 and 3). This write-only interface contains three inputs: chip-select 8 (CS), data clock (SCLK), and data in (DIN). Drive CS low to enable the serial interface and clock data synchronously into the shift register on each SCLK rising edge. The WRITE commands (C1, C0 = 00 or 01) require 16 clock cycles to clock in the command, address, and data (Figure 3a). The COPY commands (C1, C0 = 10, 11) can use either eight clock cycles to transfer only command and address bits (Figure 3b) or 16 clock cycles, with the device disregarding 8 data bits (Figure 3a). After loading data into the shift register, drive CS high to latch the data into the appropriate potentiometer control register and disable the serial interface. Keep CS low during the entire serial data stream to avoid corruption of the data. Digital-Interface Format The data format consists of three elements: command bits, address bits, and data bits (see Table 1 and Figure 3). The command bits (C1 and C0) indicate the action to be taken such as changing or storing the wiper position. The address bits (A1 and A0) specify which potentiometer the command affects and the 8 data bits (D7 to D0) specify the wiper position. _______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 — — C1 C0 — — A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 Write Wiper Register A 0 0 0 0 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 Write Wiper Register B 0 0 0 0 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 Write NV Register A 0 0 0 1 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 Write NV Register B 0 0 0 1 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 Copy Wiper Register A to NV Register A 0 0 1 0 0 0 0 1 — — — — — — — — Copy Wiper Register B to NV Register B 0 0 1 0 0 0 1 0 — — — — — — — — Copy Both Wiper Registers to NV Registers 0 0 1 0 0 0 1 1 — — — — — — — — Copy NV Register A to Wiper Register A 0 0 1 1 0 0 0 1 — — — — — — — — Copy NV Register B to Wiper Register B 0 0 1 1 0 0 1 0 — — — — — — — — Copy Both NV Registers to Wiper Registers 0 0 1 1 0 0 1 1 — — — — — — — — CLOCK EDGE CS tCSW tCSO tCSS tCL tCH tCP tCSH tCS1 SCLK tDS tDH DIN Figure 2. Timing Diagram Write-Wiper Register (Command 00) Data written to the write-wiper registers (C1, C0 = 00) controls the wiper positions. The 8 data bits (D7 to D0) indicate the position of the wiper. For example, if DIN = 0000 0000, the wiper moves to the position closest to L_. If DIN = 1111 1111, the wiper moves closest to H_. This command writes data to the volatile RAM, leaving the NV registers unchanged. When the device powers up, the data stored in the NV registers transfers to the volatile wiper register, moving the wiper to the stored position. Write-NV Register (Command 01) This command (C1, C0 = 01) stores the position of the wipers to the NV registers for use at power-up. Alternatively, the “copy wiper register to NV register” command can be used to store the position of the wipers to the NV registers. Writing to the NV registers, does not affect the position of the wipers. Copy Wiper Register to NV Register (Command 10) This command (C1, C0 = 10) stores the current position of the wiper to the NV register, for use at power-up. _______________________________________________________________________________________ 9 MAX5487/MAX5488/MAX5489 Table 1. Register Map MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers A) 16-BIT COMMAND/DATA WORD CS SCLK 1 2 DIN 3 4 C1 C0 3 4 C1 C0 5 6 7 8 9 A1 A0 D7 10 D6 11 D5 12 D4 13 D3 14 D2 15 D1 16 D0 B) 8-BIT COMMAND WORD CS SCLK 1 DIN 2 5 6 7 8 A1 A0 Figure 3. Digital-Interface Format This command may affect one potentiometer at a time, or both simultaneously, depending on the state of A1 and A0. Alternatively, the “write NV register” command can be used to store the current position of the wiper to the NV register. Copy NV Register to Wiper Register (Command 11) This command (C1, C0 = 11) restores the wiper position to the previously stored position in the NV register. This command may affect one potentiometer at a time, or both simultaneously, depending on the state of A1 and A0. Nonvolatile Memory The internal EEPROM consists of a nonvolatile register that retains the last stored value prior to power-down. The nonvolatile register is programmed to midscale at the factory. The nonvolatile memory is guaranteed for 200,000 wiper write cycles and 50 years for wiper data retention. Standby The MAX5487/MAX5488/MAX5489 feature a low-power standby mode. When the device is not being programmed, it enters into standby mode and supply current drops to 0.5µA (typ). Applications Information The MAX5487/MAX5488/MAX5489 are ideal for circuits requiring digitally controlled adjustable resistance, such as LCD contrast control (where voltage biasing adjusts the display contrast), or for programmable filters with adjustable gain and/or cutoff frequency. Positive LCD Bias Control Power-Up Figures 4 and 5 show an application where the MAX5487/MAX5488/MAX5489 provide an adjustable, positive LCD-bias voltage. The op amp provides buffering and gain to the resistor-divider network made by the potentiometer (Figure 4) or by a fixed resistor and a variable resistor (Figure 5). Upon power-up, the MAX5487/MAX5488/MAX5489 load the data stored in the nonvolatile wiper register into the volatile memory register, updating the wiper position with the data stored in the nonvolatile wiper register. This initialization period takes 5µs. Figure 6 shows the MAX5487/MAX5488/MAX5489 in a 1st-order programmable-filter application. Adjust the gain of the filter with R2, and set the cutoff frequency with R3. 10 Programmable Filter ______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers H_ 30V A =1+ W_ MAX5487 MAX5488 MAX5489 VOUT MAX480 R1 R2 L_ fC = 1 2π × R3 × C Adjustable Voltage Reference Figure 4. Positive LCD-Bias Control Using a Voltage-Divider Figure 7 shows the MAX5487/MAX5488/MAX5489 used as the feedback resistors in multiple adjustable voltage-reference applications. Independently adjust the output voltages of the MAX6160s from 1.23V to VIN 0.2V by changing the wiper positions of the MAX5487/ MAX5488/MAX5489. 5V Offset Voltage and Gain Adjustment Connect the high and low terminals of one potentiometer of a MAX5487/MAX5488/MAX5489 to the NULL inputs of a MAX410, and connect the wiper to the op amp’s positive supply to nullify the offset voltage over the operating temperature range. Install the other potentiometer in the feedback path to adjust the gain of the MAX410 (see Figure 8). 30V H_ VOUT MAX480 MAX5487 MAX5488 MAX5489 W_ L_ Chip Information TRANSISTOR COUNT: 12,177 PROCESS: BiCMOS Figure 5. Positive LCD-Bias Control Using a Variable Resistor WA V+ VIN LA HA R3 C MAX410 1/2 MAX5487 1/2 MAX5488 1/2 MAX5489 VR1 HB R2, R3 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE WB R2 1/2 MAX5487 1/2 MAX5488 1/2 MAX5489 VOUT LB Figure 6. Programmable Filter ______________________________________________________________________________________ 11 MAX5487/MAX5488/MAX5489 Use the following equations to calculate the gain (A) and the -3dB cutoff frequency (fC): 5V MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers 5V IN IN V OUT1 OUT OUT VOUT2 HB HA MAX6160 MAX6160 ADJ 1/2 MAX5487 1/2 MAX5488 1/2 MAX5489 WA R GND LA ADJ GND 1/2 MAX5487 1/2 MAX5488 1/2 MAX5489 WB R LB 10kΩ FOR THE MAX5487 R 50kΩ VOUT_ = 1.23V x FOR THE MAX5488 R 100kΩ VOUT_ = 1.23V x FOR THE MAX5489 R VOUT_ = 1.23V x R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE Figure 7. Adjustable Voltage Reference 5V WA 1/2 MAX5487/MAX5488/MAX5489 LA HA 7 3 1 8 6 MAX410 2 4 R1 R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND = D DECIMAL VALUE OF WIPER CODE HB 1/2 MAX5487/MAX5488/MAX5489 R2 WB LB Figure 8. Offset Voltage and Gain Adjustment 12 ______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers 12x16L QFN THIN.EPS D2 0.10 M C A B b D D2/2 D/2 E/2 E2/2 CL (NE - 1) X e E E2 L e CL k (ND - 1) X e CL 0.10 C CL 0.08 C A A2 A1 L L e e PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm 21-0136 E 1 ______________________________________________________________________________________ 2 13 MAX5487/MAX5488/MAX5489 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) MAX5487/MAX5488/MAX5489 Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) EXPOSED PAD VARIATIONS DOWN BONDS ALLOWED NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220 REVISION C. PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm 21-0136 E 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.