19-1435; Rev 1; 4/99 Low-Power Digital Potentiometers Features The MAX5160/MAX5161 linear-taper digital potentiometers perform the same function as a mechanical potentiometer or a variable resistor. They consist of a fixed resistor and a wiper contact with 32 tap points that are digitally controlled by three lines for the 8-pin MAX5160 or by two lines for the 6-pin MAX5161. ♦ 32 Tap Positions These parts are ideal for applications requiring digitally controlled resistors. Three resistance values are available for each part type: 50kΩ, 100kΩ, and 200kΩ. A nominal resistor temperature coefficient of 50ppm/°C end-to-end and only 5ppm/°C ratiometric makes the MAX5160 ideal for applications requiring a low-temperature-coefficient variable resistor, such as low-tempco, adjustable-gain circuit configurations. ♦ 3-Wire Serial Data Input The MAX5160 is available in an 8-pin µMAX package, and the MAX5161 is available in a 6-pin SOT23 package. Both devices are guaranteed over the extendedindustrial temperature range (-40°C to +85°C). ♦ 50kΩ, 100kΩ, and 200kΩ Resistance Values ♦ 400Ω Wiper Resistance ♦ ±25% Resistance Tolerance ♦ ±1LSB DNL ♦ ±0.5LSB INL ♦ 100nA Supply Current ♦ Single-Supply Operation: +2.7V to +5.5V ♦ Power-On Reset: Wiper Goes to Midscale (position 16) ♦ ±2kV ESD Protection ♦ Small-Footprint Packages 6-Pin SOT23 (MAX5161) 8-Pin µMAX (MAX5160) ♦ Glitchless Switching Between the Resistor Taps Applications Ordering Information LCD Screen Adjustment PART TEMP. RANGE PINPACKAGE R (kΩ) MAX5160NEUA -40°C to +85°C 8 µMAX 200 100 Volume Control Mechanical Potentiometer Replacement MAX5160MEUA -40°C to +85°C 8 µMAX MAX5160LEUA -40°C to +85°C 8 µMAX 50 MAX5161NEUT -40°C to +85°C 6 SOT23-6 200 MAX5161MEUT -40°C to +85°C 6 SOT23-6 100 MAX5161LEUT -40°C to +85°C 6 SOT23-6 50 Functional Diagram Pin Configurations H TOP VIEW VDD GND MAX5160 MAX5161 L 1 INC CS INC UP/DN COUNTER POSITION DECODER W U/D 1 U/D 2 H 3 GND 4 MAX5160 µMAX 8 VDD 7 CS 6 L 5 W H 2 MAX5161 GND 3 6 VDD 5 INC 4 U/D SOT23-6 L ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX5160/MAX5161 General Description MAX5160/MAX5161 Low-Power Digital Potentiometers ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V CS, INC, U/D to GND ...............................................-0.3V to +6V H, L, W to GND.......................................... -0.3V to (VDD + 0.3V) Input and Output Latchup Immunity ..............................±200mA Maximum Continuous Current into H, L, and W MAX516_ _ E _ _..............................................................±1mA Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C).............696mW 8-Pin µMAX (derate 4.1mW/°C above +70°C) ..............330mW Operating Temperature Range .......................... -40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec) ............................+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. ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX. Typical values are at VDD = 5V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC PERFORMANCE Resolution 3 % Integral Nonlinearity (Note 1) INL ±1/2 Differential Nonlinearity (Note 1) DNL ±1 End-to-End Resistor Tempco TCR 50 Ratiometric Resistor Tempco Zero-Scale Error Wiper Resistance RW 400 Wiper Capacitance CW 10 End-to-End Resistance HL LSB ppm/°C 5 Full-Scale Error LSB ppm/°C -0.1 LSB +0.1 LSB 1700 Ω pF MAX516_NE_ _ 150 200 250 MAX516_ME_ _ 75 100 125 MAX516_LE_ _ 37.5 50 62.5 kΩ DIGITAL INPUTS Input High Voltage VIH Input Low Voltage VIL 0.7 · VDD V 0.3 · VDD Input Leakage Current ±1 Input Capacitance 5 V µA pF TIMING CHARACTERISTICS (Figure 6) CS to INC Setup Time tCI 25 ns CS to INC Hold Time tIC 0 ns INC Low Period tIL 25 ns INC High Period tIH 25 ns U/D to INC Hold tID 0 ns U/D to INC Setup tDI 50 Wiper-Settling Time tIW INC Frequency ns 1 fIMAX µs 7 MHz 5.5 10 V µA nA POWER SUPPLIES Supply Voltage Supply Current VDD IDD 2.7 CS = INC = U/D = VDD or GND VDD = 5V VDD = 2.7V 0.6 135 Note 1: For the MAX5160, linearity is defined in terms of H to L code-dependent resistance. 2 _______________________________________________________________________________________ Low-Power Digital Potentiometers 800 END-TO-END RESISTANCE % CHANGE RWMAX = 574.0804 WIPER RESISTANCE (Ω) 0.06 MAX5160/61 toc01 1,000 VDD = +2.7V 600 400 VDD = +5V 200 200kΩ 50kΩ 0.04 0.02 100kΩ MAX5160/61 toc02 END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE WIPER RESISTANCE vs. WIPER VOLTAGE 0 -0.02 100kΩ 200kΩ -0.04 50kΩ -0.06 -0.08 -0.1 -0.12 -0.14 0 0 1 2 3 4 WIPER VOLTAGE (V) TEMPERATURE (°C) END-TO-END RESISTANCE vs. TAP POSITION END-TO-END RESISTANCE vs. TAP POSITION MAX5160/61 toc04 200kΩ 175 100kΩ 100 90 80 RESISTANCE (kΩ) 150 125 100 75 70 60 50 40 30 50 20 25 10 0 5 9 13 17 21 25 29 0 33 1 TAP POSITION 5 9 13 17 21 25 29 33 TAP POSITION END-TO-END RESISTANCE vs. TAP POSITION 50 MAX5160/61 toc05 1 50kΩ 45 40 RESISTANCE (kΩ) RESISTANCE (kΩ) 110 MAX5160/61 toc03 225 200 -0.16 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 5 35 30 25 20 15 10 5 0 1 5 9 13 17 21 25 29 33 TAP POSITION _______________________________________________________________________________________ 3 MAX5160/MAX5161 Typical Operating Characteristics (VDD = +5V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = +5V, TA = +25°C, unless otherwise noted.) MAX5160/61 toc06 0.8 0.7 0.6 MAX5160/61 toc07 TAP-TO-TAP SWITCHING TRANSIENT SUPPLY CURRENT vs. TEMPERATURE 0.9 SUPPLY CURRENT (µA) MAX5160/MAX5161 Low-Power Digital Potentiometers OUTPUT W 50mV/div VDD = +5V 0.5 0.4 0V 0.3 0.2 INC 2V/div VDD = +2.7V 0V 0.1 0 -40 -20 0 20 40 60 80 5µs/div 100 TEMPERATURE (°C) Pin Description PIN PIN NAME 4 FUNCTION MAX5160 MAX5161 1 5 INC Wiper Increment Control Input. With CS low, a high-to-low transition increments (U/D high) or decrements (U/D low) the wiper position. 2 4 U/D Up/Down Control Input. With CS low, a high-to-low INC transition increments (U/D high) or decrements (U/D low) the wiper position. 3 2 H 4 3 GND 5 — W Wiper Terminal of Resistor 6 1 L Low Terminal of Resistor 7 — CS Chip-Select Input. Drive low to change the wiper position via INC and U/D. 8 6 VDD Power Supply High Terminal of Resistor Ground _______________________________________________________________________________________ Low-Power Digital Potentiometers The MAX5160/MAX5161 consist of resistor arrays with 31 resistive elements. Thirty-two tap points are accessible to the wiper along the resistor string between H and L. Logic inputs CS, U/D, and INC determine the position of the wiper. With CS low and U/D high, a high-tolow transition on INC increments the internal counter, increasing the resistance between W and L. When both CS and U/D are low, a high-to-low INC transition decrements the internal counter, decreasing the resistance between W and L. At either end (maximum or minimum positions), additional transitions in the direction of the end points will not change the counter value (the counter will not wrap around). The H and L terminals of the MAX5160 are similar to the two end terminals of a mechanical potentiometer. The tap W is equivalent to the variable tap (wiper) of the potentiometer. The MAX5161 is similar to the MAX5160 except that CS internally connects to ground and the wiper terminal (W) is shorted to the high terminal (H). The MAX5161 acts as a variable resistor (a potentiometer with the wiper and one end terminal shorted together). The MAX5160/MAX5161 feature power-on reset circuitry that sets the wiper position to midscale at power-up. Applications Information The MAX5160/MAX5161 are intended for circuits requiring digitally controlled adjustable voltage or adjustable gain, such as LCD contrast control, where voltage biasing adjusts the display contrast. Controlling a Switch-Mode LCD Bias Generator Figure 1 shows an application where the MAX5161 is used with a MAX1771 to make an adjustable positive LCD-bias circuit. The output of the MAX1771 is a positive voltage that is digitally controlled through the MAX5160/MAX5161. Similarly, Figure 2 shows the application of the MAX5161 in a digitally controlled negative LCD-bias circuit along with the MAX774/ MAX775/MAX776. VIN = 5V C1 68µF VIN C2 0.1µF 2 L1 22µH V+ 5 REF C3 0.1µF 4 SHDN MAX1771 6 AGND EXT CS FB 1 C1 150µF VOUT = 12V AT 0.5A D1 1N5817-22 C4 300µF C2 0.1µF R2 MAX5161 N MTD20N03HDL 1 OUT 3 V+ 5 R3 0.07Ω SHDN MAX774 2 FB MAX775 CS 6 MAX776 7 EXT Q1 Si9435 P VOUT RVAR 8 3 RSENSE 40mΩ R1 R2 GND 7 4 C3 0.1µF C5 1N5822/ MBR340 L1 22µH REF GND 8 C4* RVAR MAX5161 * MAX774 = 330µF, 10V MAX775, MAX776 = 120µF, 20V R1 VREF = 1.5V VOUT(MAX) R2 VOUT(MIN) R2 = , = R1 VREF R1 + RVAR VREF VOUT(MAX) R2 = +1 R1 VREF ( VOUT(MIN) R2 = R1 + RVAR(MAX) VREF Figure 1. Adjustable Positive LCD Bias ) +1 VREF - VFB 5µA (FOR 2% GAIN-SETTING ACCURACY) R1 + RVAR Figure 2. Adjustable Negative LCD Bias _______________________________________________________________________________________ 5 MAX5160/MAX5161 Detailed Description MAX5160/MAX5161 Low-Power Digital Potentiometers Alternative Positive LCD Bias Control Alternatively, use an op amp to provide buffering and gain to the output of the MAX5160/MAX5161. Connect the MAX5160 to the positive input of a noninverting op amp (Figure 3) to select a portion of the input signal by digitally controlling the wiper terminal. Figure 4 shows a similar circuit for the MAX5161. Adjustable Gain Figure 5 shows how to use the MAX5161 to digitally adjust the gain of a noninverting op amp configuration. Connect the MAX5161 in series with a resistor to ground to form the adjustable gain control of a noninverting amplifier. The MAX5160/MAX5161 have a low 5ppm/°C ratiometric tempco that allows for a very stable adjustable gain configuration over temperature. Serial Interface Figure 6 is the serial-interface timing diagram. +5V +5V +5V +5V H MAX5161 MAX5160 H INC U/D 30V VDD INC U/D CS GND W 30V VDD GND VOUT VOUT L L GAIN 6 GAIN 6 Figure 3. MAX5160 Positive LCD Bias Control Figure 4. MAX5161 Positive LCD Bias Control VCC VCC VIN VIN VOUT VOUT +5V H INC U/D W H L MAX5161 VDD GND L MAX5160 a) b) Figure 5. Adjustable Gain Circuit: a) MAX5161; b) MAX5160 6 _______________________________________________________________________________________ Low-Power Digital Potentiometers MAX5160/MAX5161 CS tCI tIC tIL INC tIH tDI U/D tID tIW W Figure 6. Serial-Interface Timing Diagram Chip Information Truth Table CS U/D INC RW H xx-X X O L L ↑ O L H ↑ O L L ↓ — L H ↓ + TRANSISTOR COUNT: 969 X = Don’t care O = Previous state + = Increment — = Decrement ↓ = High-to-Low Transition ↑ = Low-to-High Transition _______________________________________________________________________________________ 7 Low-Power Digital Potentiometers 6LSOT.EPS 8LUMAXD.EPS MAX5160/MAX5161 Package Information 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.