MAX5407EKA

19-2196; Rev 0; 10/01 32-Tap Audio Logarithmic Taper Digital Potentiometer Features ♦ Miniature 3mm x 3mm 8-Pin SOT23 Package ♦ Logarithmic Taper with 1dB Steps Between Taps ♦ 32 Tap Positions ♦ Low 0.35µA Supply Current ♦ +2.7V to +5.5V Single-Supply Operation ♦ Zero-Crossing Detection to Minimize Audible Clicks During Wiper Transitions ♦ Simple Up/Down 2-Wire Serial Data Interface ♦ Power-On Reset Wiper Goes To Maximum Attenuation (Lowest Tap Position) ♦ 20kΩ End-to-End Resistance Applications Ordering Information Audio Volume Control Fading/Balancing Audio Signals Mechanical Potentiometer Replacement PART TEMP. RANGE PINPACKAGE TOP MARK MAX5407EKA -40°C to +85°C 8 SOT23 AAID Pin Configuration Functional Diagram H TOP VIEW VDD GND CS U/D MAX5407 UP/DOWN COUNTER 32-POSITION DECODER W ZCEN ZCEN H 1 8 GND 2 7 VDD W 3 6 CS L 4 5 U/D MAX5407 SOT23 L SOT-PoT is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ 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 MAX5407 General Description The MAX5407 SOT-PoT™ is a logarithmic taper digital potentiometer with 32 tap points that has 1dB steps between taps. This device is ideal for audio applications, such as volume control and fading/balancing audio signals. The MAX5407 consists of a resistor string and CMOS switches that are digitally controlled through a simple 2wire serial interface. This device performs the same function as a mechanical potentiometer. The device has a fixed end-to-end resistance of 20kΩ and features zero-crossing detection to minimize the audible noise generated by the wiper transitions. This device has nominal resistor temperature coefficients of 35ppm/°C end-to-end and 5ppm/°C ratiometric. The MAX5407 is available in a space saving 8-pin SOT23 package and is guaranteed from -40°C to +85°C. MAX5407 32-Tap Audio Logarithmic Taper Digital Potentiometer ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V H, W, L, CS, ZCEN, and U/D to GND .........-0.3V to (VDD + 0.3V) Input and Output Latchup Immunity...............................±200mA Maximum Continuous Current into H, L, and W ..............±500µA Continuous Power Dissipation (TA = +70°C) 8-Pin SOT23-8 (derate 8.9mW/°C above +70°C) ......714mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Soldering 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. ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN Number of Resistor Taps 32 End-to-End Resistance 15 TYP MAX UNITS Taps 20 25 Bandwidth (Note 2) (Notes 3, 4) Absolute Tolerance (Note 5) (Note 3) ±0.25 ±1 dB Tap-to-Tap Tolerance (Note 6) (Note 3) ±0.05 ±0.1 dB VIN = 1VRMS, f = 1kHz, Tap = -6dB (Notes 3, 4) 0.002 % PSRR -80 dB TCR 35 ppm/°C 5 ppm/°C Total Harmonic Distortion + Noise Power-Supply Rejection Ratio End-to-End Resistance Temperature Coefficient Ratiometric Resistance Temperature Coefficient Wiper Resistance THD + N RW 500 kΩ VDD = 2.7V 400 kHz 1700 Ω DIGITAL INPUTS Input High Voltage VIH Input Low Voltage VIL 2.4 V Input Leakage Current Input Capacitance 0.8 V ±1 µA 5 pF TIMING CHARACTERISTICS (Figures 1, 2) U/D Mode to CS Setup tCU 25 ns CS to U/D Step Setup tCI 25 ns CS to U/D Step Hold tIC 25 ns U/D Step Low Period tIL 25 ns U/D Step High Period tIH 25 ns Up/Down Toggle Rate fTOGGLE Wiper Switching Time tIW Zero-Crossing Timeout 2 7 Zero-crossing detection disabled (Note 4) MHz 0.1 µs 50 ms _______________________________________________________________________________________ 32-Tap Audio Logarithmic Taper Digital Potentiometer (VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V POWER SUPPLIES Supply Voltage VDD Supply Current Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: 2.7 All digital inputs are set to 0 IDD Active (Note 7) 100 Standby (Note 8) 0.35 µA 1 All devices are 100% production tested at TA = +25°C and guaranteed by design for TA = TMIN to TMAX. Bandwidth is measured from H to W at the -6dB wiper tap position (see Typical Operating Characteristics). These specifications are only valid for IW less than 100nA of continuous wiper current. Measured with 20pF load capacitor. Absolute tolerance is defined as the variation of the attenuation for any given tap from its expected value. Tap-to-tap tolerance is defined as the variation between any two adjacent taps from the typical value of 1dB. Supply current when fTOGGLE = 2MHz. Supply current when wiper position is not changing. Typical Operating Characteristics (VDD = +5V, TA = +25°C, unless otherwise noted.) WIPER RESISTANCE vs. WIPER VOLTAGE END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE 200 VDD = +5V 150 -0.05 -0.10 0 1 2 3 WIPER VOLTAGE (V) 4 5 -10 -15 -20 -25 -0.15 -30 -0.20 -35 -0.25 100 -5 0.05 0 MAX5407 toc03 0.10 ATTENUATION (dB) WIPER RESISTANCE (Ω) 250 ATTENUATION vs. TAP POSITION 0 MAX5407 toc02 VDD = +3V 300 0.15 ENE-TO-END RESISTANCE CHANGE (%) MAX5407 toc01 350 -40 -15 10 35 TEMPERATURE (°C) 60 85 0 4 8 12 16 20 24 28 32 TAP POSITION _______________________________________________________________________________________ 3 MAX5407 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VDD = +5V, TA = +25°C, unless otherwise noted.) 0.40 VDD = +5V 0.35 U/D 2V/div 0.30 0.25 0.20 VDD = +3V 0.15 OUTPUT W 200mV/div 0.10 0.40 MAX5407 toc06 0.45 STANDBY SUPPLY CURRENT (µA) MAX5407 toc04 0.50 STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE TAP-TO-TAP SWITCHING TRANSIENT MAX5407 toc05 SUPPLY CURRENT vs. TEMPERATURE 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.05 0 0 -40 -15 10 35 60 2.5 40ns/div 85 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) TEMPERATURE (°C) TOTAL HARMONIC DISTORTION + NOISE vs. FREQUENCY FREQUENCY RESPONSE 0.01 MAX5407 toc07 0 TAP POSITION 6 MAX5407 toc08 SUPPLY CURRENT (µA) TAP POSITION 6 -5 THD+N (%) 0.001 GAIN (dB) MAX5407 32-Tap Audio Logarithmic Taper Digital Potentiometer -10 0.0001 -15 -20 0.001 0.00001 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 FREQUENCY (kHz) FREQUENCY (kHz) Pin Description 4 PIN NAME FUNCTION 1 H 2 GND 3 W Wiper Terminal of Resistor 4 L Low Terminal of Resistor 5 U/D Up/Down Control Input. With CS high, a low-to-high transition increments or decrements the wiper position, depending on the mode. 6 CS Chip-Select Input. A low-to-high CS transition determines the mode: increment if U/D is high, decrement if U/D is low. 7 VDD Power Supply 8 ZCEN High Terminal of Resistor Ground Zero-Crossing Detection Enable Input. Set to low to enable zero-crossing detection. _______________________________________________________________________________________ 32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407 CS tCU tIC tIL U/D tIH tCI tIW W NOTE: W IS NOT A DIGITAL SIGNAL. IT REPRESENTS THE WIPER TRANSITIONING. Figure 1. Serial Interface Timing Diagram, Increment Mode CS tCU tIC tIH U/D tCI tIL W tIW NOTE: W IS NOT A DIGITAL SIGNAL. IT REPRESENTS THE WIPER TRANSITIONING. Figure 2. Serial Interface Timing Diagram, Decrement Mode Detailed Description Digital Interface Operation The MAX5407 has two modes of operation when the serial interface is active: increment and decrement mode. The serial interface is only active when CS is high. The CS and U/D inputs control the position of the wiper along the resistor array. When CS transitions from low to high, the part will go into increment mode if U/D is high and into decrement mode if U/D is low. Once the mode is set, the device will remain in that mode until CS goes low again. A low-to-high transition at the U/D pin will increment or decrement the wiper position depending on the mode (Figures 1 and 2). When the CS input transitions to low (serial interface inactive), the value of the counter is stored and the wiper position is maintained. _______________________________________________________________________________________ 5 MAX5407 32-Tap Audio Logarithmic Taper Digital Potentiometer Power-On Reset The power-on reset feature sets the wiper to the maximum attenuation (tap position 31, -31dB) at power-up. If CS is initially high, the MAX5407 is in the increment mode by default. Zero-Crossing Detection When the ZCEN input is low, the zero-crossing detect feature is enabled. This feature reduces the audible noise (“clicks and pops”) that result from wiper transitions. When zero-crossing detection is enabled, the wiper changes position only when the voltage at L is the same as the voltage at H. If no zero crossing is detected after 50ms, the device will timeout and change the wiper position. Digital Logic Inputs The MAX5407 can interface to +3V logic as well as +5V logic, while using a +3V to +5V power supply. In order to minimize the supply current, set all digital inputs low while the part is inactive. Applications Information The MAX5407 is intended for circuits requiring digitally controlled adjustable voltage or adjustable gain, such as applications involving volume control. Volume Control The zero-crossing feature of the MAX5407 makes it ideal for applications involving volume control. Figure 3 shows a typical application circuit, where the MAX5407 is followed by an op amp for output buffering and gain. VCM represents the common voltage around which the audio signal swings. Signal Attenuator Figure 4 shows a typical signal attenuator. Use an op amp to provide buffering and gain to the output of the MAX5407. Connect the MAX5407 to the positive input of a noninverting op amp to select the level of attenuation of the input signal, by digitally controlling the wiper terminal. Adjustable Gain Figure 5 shows how to use the MAX5407 to digitally adjust the gain of a noninverting op amp configuration. The MAX5407 has a low 5ppm/°C ratiometric tempco that allows for a very stable adjustable gain configuration over temperature. AUDIO INPUT MAX5407 +5V H CS W U/D ZCEN VDD VDD MAX4336 L VCM Chip Information VOUT TRANSISTOR COUNT: 1942 Figure 3. Volume Control Circuit MAX5407 MAX5407 SIGNAL INPUT VDD +5V H CS W U/D VDD VDD MAX4336 +5V ZCEN VIN L MAX4336 VOUT W L H MAX5407 Figure 4. Signal Attenuator Circuit 6 Figure 5. Adjustable Gain Circuit _______________________________________________________________________________________ VOUT 32-Tap Audio Logarithmic Taper Digital Potentiometer SOT23, 8L.EPS 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX5407 Package Information