19-0672; Rev 0; 11/06 Stereo Volume Control with Pushbutton Interface The MAX5486 dual 40kΩ logarithmic taper volume control features a debounced pushbutton up/down interface that controls volume and balance in audio applications. Each potentiometer has 32 log-spaced tap points with a buffered wiper output to replace mechanical potentiometers. An integrated bias generator provides the required ((VDD + VSS) / 2) bias voltage, eliminating the need for costly external op-amp circuits in unipolar audio applications. A mode-indicator LED output indicates volume or balance control. Five integrated LED drivers indicate volume level or balance settings, depending on the status of the mode indicator. Use the MAX5486 digital inputs with momentary contact single-pole/single-throw (SPST) pushbutton switches. Each input includes internal debounced circuitry and a pullup resistor to VLOGIC. The MAX5486 advances the wiper setting once per button push. Maxim’s proprietary SmartWiper™ control eliminates the need for a microcomputer to increase the wiper transition rate. The accelerated auto-advance feature provides a wiper-changing rate at 4Hz for holding the control input low for more than 250ms and at 8Hz after 500ms and then at 11Hz after 1000ms (see Table 2). All of the MAX5486’s pushbutton inputs are debounced. The mute input allows a single pushbutton to change between volume control and the -90dB (typ) mute setting. The mode input toggles between volume and balance control. The click-and-pop suppression feature minimizes the audible noise generated by wiper transitions. The typical total harmonic distortion plus noise (THD+N) for the device is 0.003%. The MAX5486 provides a nominal temperature coefficient of 35ppm/°C end-to-end and 5ppm/°C ratiometrically and a nominal resistance of 40kΩ per potentiometer. The MAX5486 is available in a 24-pin TSSOP package and is specified for operation over the -40°C to +85°C extended temperature range. Applications Features ♦ Debounced Pushbutton Interface ♦ SmartWiper Control Advances Wiper Rate ♦ Low-Power Wiper Buffers Provide 0.003% THD+N ♦ Bias Generator Eliminates External Op Amps ♦ Five-Segment LED Volume/Balance Indicator ♦ Clickless Switching ♦ Logarithmic Taper Volume Control with (31) 2dB Steps ♦ Single +2.7V to +5.5V or Dual ±2.7V Supply Voltage Operation ♦ Power-On Reset to -12dBFS Wiper Position ♦ MUTE Function Toggles to 90dB (typ) ♦ Low 1µA Shutdown Supply Current ♦ 40kΩ End-to-End Fixed Resistance Value ♦ Small, 24-Pin TSSOP Package Ordering Information PART TEMP RANGE PINPACKAGE PKG CODE MAX5486EUG+ -40°C to +85°C 24 TSSOP U24-1 +Denotes lead-free package. Typical Operating Circuit VDD VLOGIC VLOGIC SHDN VPEAK MODEIND (VDD + VSS) / 2 MAX5486 HR WR 1MΩ RIGHT INPUT Home-Theater Speakers LR MAX9761 Desktop Speakers Portable Media Players Docking Stations BIAS (VDD + VSS) / 2 LEDIND0 LL WL LEDIND2 LEDIND3 Automotive Rear-Seat Multimedia LEFT INPUT LEDIND1 HL VPEAK (VDD + VSS) / 2 LEDIND4 BIASCAP GND VSS MUTE UP/BALL DN/BALR MODE SmartWiper 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 MAX5486 General Description MAX5486 Stereo Volume Control with Pushbutton Interface ABSOLUTE MAXIMUM RATINGS SHDN, MODE, MUTE, UP/BALL, and DN/BALR to GND .................-0.3V to the lower of (VLOGIC + 0.3V and +6V) H_, L_, W_, BIASCAP, BIAS to GND .........-0.3V to the lower of (VDD + 0.3V and +6V) LEDIND_, MODEIND to GND ...................................-0.3V to +6V VLOGIC to GND.........................................................-0.3V to +6V VDD to GND ..............................................................-0.3V to +6V VDD to VLOGIC .............................................................-6V to +6V GND to VSS...............................................................-0.3V to +6V VDD to VSS ................................................................-0.3V to +6V Average Current into H_, L_, and W_ .................................±1mA Maximum Continuous Current into H_, L_ ..........................±4mA Input and Output Latchup Immunity...............................±200mA Continuous Power Dissipation (TA = +70°C) 24-Pin TSSOP (derate 8.3mW/°C above +70°C) ..........657mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-60°C to +150°C Maximum Junction Temperature .....................................+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. ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.5V, VSS = GND = 0, 2.7V ≤ (VDD - VSS) ≤ 5.5V, CBIASCAP = 1µF, BIAS = 3kΩ to GND, VLOGIC = +2.7V to VDD, VH_ = VDD - 0.15V, VL_ = (VDD - VSS) / 2, SHDN = MUTE = VLOGIC, all LED outputs open, pushbutton interface inactive, VH = VBIAS + 1VRMS, VBIAS = (VDD - VSS) / 2, TA = TMIN to TMAX, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RESISTOR LADDER End-to-End Resistance R 40 Absolute Tolerance Tap-to-Tap Tolerance kΩ ±0.25 dB (Note 2) ±0.1 dB VDD = 5V, VSS = 0, VH = (VDD / 2) + 1VRMS, VL = VDD / 2, 1kHz, tap at top, RL = 10kΩ to VL = VDD / 2, 20Hz to 20kHz 0.003 VDD = 5V, VSS = 0, VH = (VDD / 2) + 1VRMS, VL = VDD / 2, 1kHz, tap at top, RL = ∞Ω to VL = VDD / 2, 20Hz to 20kHz 0.001 VDD = 5V, VSS = 0, VH = (VDD / 2) + 1.5VRMS, VL = VDD / 2, 1kHz, tap at top, RL = 10kΩ to VL = VDD / 2, 20Hz to 20kHz 0.012 VOLUME CONTROL Total Harmonic Distortion Plus Noise THD+N Channel Isolation VDD = +2.7V, VSS = -2.7V, VBIAS = GND Interchannel Matching Mute Attenuation Power-Supply Rejection Ratio PSRR % 100 dB ±0.5 dB SHDN = VDD 90 dB Input referred, 217Hz, 100mVP-P on VDD 72 dB H Terminal Capacitance CH 5 pF L Terminal Capacitance CL 7 pF End-to-End Resistance Temperature Coefficient 35 ppm/°C Ratiometric Resistance Temperature Coefficient 5 ppm/°C 100 kHz Bandwidth, -3dB 2 fCUTOFF CW = 50pF _______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface (VDD = +2.7V to +5.5V, VSS = GND = 0, 2.7V ≤ (VDD - VSS) ≤ 5.5V, CBIASCAP = 1µF, BIAS = 3kΩ to GND, VLOGIC = +2.7V to VDD, VH_ = VDD - 0.15V, VL_ = (VDD - VSS) / 2, SHDN = MUTE = VLOGIC, all LED outputs open, pushbutton interface inactive, VH = VBIAS + 1VRMS, VBIAS = (VDD - VSS) / 2, TA = TMIN to TMAX, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER Output Noise SYMBOL CONDITIONS eN 20Hz to 20kHz, VH = VL = VDD / 2 = AC ground, tap = -6dB VO RL = 3kΩ to VBIAS MIN TYP MAX UNITS 2.2 µVRMS VDD 0.3V V WIPER BUFFER Output Voltage Swing Output Current 3 Output Resistance DC Offset mA ROWB 1 10 Ω VOS ±2 ±14 mV INTEGRATED BIAS GENERATOR Output Voltage RL > 100kΩ Power-Supply Rejection Ratio At 1kHz, 100mVP-P on VDD (VDD + (VDD + (VDD + VSS) / 2 VSS) / 2 VSS) / 2 - 20mV + 20mV V 60 dB Minimum Load Resistance Maximum Load Capacitance Output Resistance ROBR Noise Voltage 20Hz to 20kHz Minimum Output Current 3 kΩ 100 pF 6 Ω 2.2 µVRMS 2 mA 42 kΩ CONTACT INPUTS (MUTE, MODE, UP/BALL, DN/BALR) Internal Pullup Resistor RPU Single-Pulse Input Low Time tCPW Repetitive Input Pulse Separation Time tIPWS Timeout Period tWS Debounce Corner Frequency Time required for a single pulse to cause an increment/decrement 16 ms 1 ms Click-and-pop suppression inactive 126 ms Internal analog filter 10 kHz DIGITAL INPUTS (VLOGIC > 4.5V) Input High Voltage VIH Input Low Voltage VIL Input Leakage Current VLOGIC > 4.5V 2.4 VLOGIC < 4.5V 0.7 x VLOGIC VLOGIC > 4.5V 0.8 VLOGIC < 4.5V 0.3 x VLOGIC V ±1 µA To GND for inputs with internal pullup resistors Input Capacitance Digital Clock Feedthrough V fCLK = 1Hz to 40Hz, tap = -6dB 5 pF -90 dB _______________________________________________________________________________________ 3 MAX5486 ELECTRICAL CHARACTERISTICS (continued) MAX5486 Stereo Volume Control with Pushbutton Interface ELECTRICAL CHARACTERISTICS (continued) (VDD = +2.7V to +5.5V, VSS = GND = 0, 2.7V ≤ (VDD - VSS) ≤ 5.5V, CBIASCAP = 1µF, BIAS = 3kΩ to GND, VLOGIC = +2.7V to VDD, VH_ = VDD - 0.15V, VL_ = (VDD - VSS) / 2, SHDN = MUTE = VLOGIC, all LED outputs open, pushbutton interface inactive, VH = VBIAS + 1VRMS, VBIAS = (VDD - VSS) / 2, TA = TMIN to TMAX, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V POWER SUPPLIES Positive Power Supply VDD Negative Power Supply VSS Supply-Voltage Difference Analog Supply Current Power-Up Time IDD VSS = 0 2.7 VDD = +2.7V -2.7 0 V VDD - VSS 5.5 V (Note 3) 1.4 mA tPU 126 Logic Supply Voltage VLOGIC VSS = 0 Logic Active Supply Current ILOGIC VLOGIC = VDD (Note 4) Logic Standby Supply Current (Note 3) ILOGICSTBY 2.7 ms VDD V 200 µA VDD = +5V, VSS = 0 1 VDD = +2.7V, VSS = -2.7V 1 µA Shutdown Current ISHDN SHDN = 0, total of all supplies 1 µA Shutdown Time/Return from Shutdown tSHDN After 1st zero crossing 1 ms LED INDICATORS (LEDIND0–LEDIND4, MODEIND) Output Low Voltage VOL VLOGIC = 2.7V, ISINK = 10mA 0.4 VLOGIC = 5V, ISINK = 10mA 0.2 V Maximum Output Leakage Current 10 µA Output Capacitance 3 pF Note 1: Note 2: Note 3: Note 4: 4 Parameters are 100% production tested at +85°C and limits through the temperature range are guaranteed by design. Tap-to-tap tolerance is the error in voltage change between successive tap positions. Supply current measured while wiper position is fixed. One button pressed. _______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE ATTENUATION vs. TAP POSITION -20 -30 -40 -50 -60 -70 MAX5486 toc02 END-TO-END RESISTANCE CHANGE (%) -10 VDD = VLOGIC = 5V VSS = GND = 0 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25 0 4 8 12 16 20 24 28 32 -40 -15 10 35 60 85 TAP POSITION TEMPERATURE (°C) WIPER SWITCHING TRANSIENT WIPER-TO-END TERMINAL VOLTAGE vs. TAP POSITION MAX5486 toc03 NOMINAL END-TO-END VOLTAGE (%VHL) 100 DN 5V/div 200mV/div WIPER TRANSITION FROM -2dB TO -4dB MAX5486 toc04 ATTENUATION (dB) 0.15 MAX5486 toc01 0 VHW 90 80 70 60 50 40 30 20 10 VWL 0 0 40ms/div 4 8 12 16 20 24 28 32 TAP POSITION TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 10 W_ SET TO 0dB VDD = 5V VSS = GND VL_ = 2.5V W_ SET TO 0dB -5 W_ SET TO -6dB -10 RESPONSE (dB) 1 THD+N (%) RESPONSE (dB) 0 POWER-SUPPLY REJECTION RATIO 10kΩ OR NO LOAD 0.1 VH_ = 2.5V ±1.5VRMS 0.01 W_ SET TO -12dB -15 VH_ = 2.5V ±1VRMS 0.001 W_ SET TO -18dB 10kΩ OR NO LOAD -20 0.0001 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 0.01 0.1 1 FREQUENCY (kHz) 10 100 -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 MAX5486 toc07 VH1 = 2.5V ±1VRMS, VL1 = 2.5V 100 MAX5486 toc05 5 MAX5486 toc06 FREQUENCY RESPONSE VDD = 5V ±100mVP-P, VSS = GND VH_ = 5V, VL_ = 2.5V W_ SET TO -6dB 0.01 0.1 1 10 100 FREQUENCY (kHz) _______________________________________________________________________________________ 5 MAX5486 Typical Operating Characteristics (VDD = +5.0V, VSS = GND = 0, VLOGIC = +5.0, VH_ = VDD - 0.15V, VL_ = VDD / 2, CBIASCAP = 1µF) Typical Operating Characteristics (continued) (VDD = +5.0V, VSS = GND = 0, VLOGIC = +5.0, VH_ = VDD - 0.15V, VL_ = VDD / 2, CBIASCAP = 1µF) 100 80 60 40 STANDBY CURRENT 100 MAX5486 toc10 VDD = VLOGIC = 5.5V 148 ACTIVE ILOGIC (μA) ACTIVE CURRENT 120 150 MAX5486 toc09 140 1000 LOGIC SUPPLY CUURENT (μA) MAX5486 toc08 160 LOGIC SUPPLY CURRENT (μA) ACTIVE LOGIC SUPPLY CURRENT vs. TEMPERATURE LOGIC SUPPLY CURRENT vs. LOGIC INPUT VOLTAGE LOGIC SUPPLY CURRENT vs. LOGIC SUPPLY VOLTAGE 146 144 142 20 10 0 3.5 4.0 4.5 5.0 140 0 5.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 ACTIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.0 0.5 VDD = VLOGIC = 5.5V UP = 0 4 5 1.0 6 CROSSTALK (dB) 200 150 100 0 -15 10 35 60 85 0.01 0.1 1 DIGITAL FEEDTHROUGH MAX5486 toc14 MAX5486 toc15 VDD = 2.7V, VSS = -2.7V, VLOGIC = 5V W_SET TO 0dB, VHR = 1VRMS VLR = VLL = VHL = 0V WIPER OUTPUT 50μV/div -60 PUSHBUTTON INPUT -80 -100 2V/div -120 -140 -160 0.01 0.1 1 10 100 500ns/div FREQUENCY (Hz) 6 10 FREQUENCY (kHz) TEMPERATURE (°C) CROSSTALK vs. FREQUENCY -40 250 50 -40 0 85 0.5 SUPPLY VOLTAGE (V) -20 60 SPECTRAL NOISE DENSITY 0 3 35 1.5 0 2 10 300 NOISE (nV/√Hz) 1.5 2.0 ACTIVE SUPPLY CURRENT (mA) MAX5486 toc11 UP = 0 VLOGIC = 5.5V 1 -15 TEMPERATURE (°C) ACTIVE SUPPLY CURRENT vs. TEMPERATURE 2.0 0 -40 LOGIC INPUT VOLTAGE (V) LOGIC SUPPLY VOLTAGE (V) MAX5486 toc13 3.0 MAX5486 toc12 2.5 ACTIVE SUPPLY CURRENT (mA) MAX5486 Stereo Volume Control with Pushbutton Interface _______________________________________________________________________________________ 100 Stereo Volume Control with Pushbutton Interface PIN NAME FUNCTION Digital Logic Power Supply. Bypass VLOGIC to ground with a 0.1µF capacitor as close as possible to the device. 1 VLOGIC 2 DN/BALR Active-Low Downward Volume/Balance Control. Press DN/BALR to decrease the volume in volume mode and move balance to the right in balance mode. DN/BALR is internally pulled high with a resistor to VLOGIC. 3 UP/BALL Active-Low Upward Volume/Balance Control. Press UP/BALL to increase the volume in volume mode and move balance to the left in balance mode. UP/BALL is internally pulled high with a resistor to VLOGIC. 4 MUTE Active-Low Mute Input. Pull MUTE low to toggle the wiper between the mute setting (see Table 1) and the current setting. MUTE is internally pulled up to VLOGIC with a resistor. 5 MODE Active-Low Volume/Balance Control Input. Each high-to-low transition on MODE toggles between the volume and balance modes. MODE is pulled high internally with a resistor to VLOGIC. On power-up, the MAX5486 is in volume control mode. 6 SHDN Active-Low Shutdown Input. Drive SHDN low to place the device in shutdown mode. In shutdown mode, the MAX5486 stores the last wiper settings. The wipers move to the L_ end of the resistor string. Terminating the shutdown mode restores the wipers to the previous settings. 7 N.C. 8 HR Potentiometer R High Terminal 9 LR Potentiometer R Low Terminal 10 WR Potentiometer R Wiper Buffered Output 11 BIAS 12 BIASCAP 13 VDD Analog Power Supply. Bypass VDD to ground with a 0.1µF capacitor as close as possible to the device. 14 VSS Negative Power Supply. Bypass VSS to ground with a 0.1µF capacitor as close as possible to the device. Connect to GND for single supply operation. 15 WL Potentiometer L Wiper Buffered Output 16 LL Potentiometer L Low Terminal 17 HL Potentiometer L High Terminal Internally connected. Leave unconnected. Midbias Voltage Output. VBIAS = (VDD + VSS) / 2; connect a 100pF capacitor from BIAS to VSS. Bias Generator Bypass. Connect a 1µF filter capacitor from BIASCAP to VSS. 18–22 LEDIND0– LEDIND4 LED Indicator Open-Drain Output 0–LED Indicator Open-Drain Output 4. Connect a 1MΩ resistor from LEDIND4 to VLOGIC to enable these LED inductor drivers. LEDIND0–LEDIND4 form a bar graph indication of the current volume or balance. In volume mode, all LEDs off indicate mute and all LEDs on indicate maximum volume. In balanced mode, LED2 on indicates centered or balanced. Connect LEDIND0–LEDIND4 to GND when LED indicator drivers are not used. 23 MODEIND Active-Low Volume-Control/Balance-Control Mode-Indicator Open-Drain Output. Connect to an LED through a resistor to VLOGIC. When the LED is on, the MAX5486 is in balance-control mode. When the LED is off, the MAX5486 is in volume-control mode. 24 GND Ground _______________________________________________________________________________________ 7 MAX5486 Pin Description MAX5486 Stereo Volume Control with Pushbutton Interface Detailed Description VLOGIC The MAX5486 dual 40kΩ logarithmic taper digital volume control features a debounced pushbutton interface that controls volume and balance in audio applications. Each potentiometer has 32 log-spaced tap points with a buffered wiper output and replaces mechanical potentiometers. UP Mode Control (MODE) The MAX5486 MODE input toggles between volume and balance modes. Each time MODE is forced low, the device switches between volume and balance modes. For example, driving MODE low once while in volume-control mode switches the MAX5486 to balance mode. Driving MODE low again switches the MAX5486 back to volume mode. MODE is internally pulled high with a resistor to VLOGIC. The MAX5486 powers up in volume-control mode. Leave unconnected or connect to VLOGIC if balance mode is not required. Up-and-Down Interface The MAX5486 interfaces with momentary contact SPST switches. All switch inputs are internally debounced and pulled up to VLOGIC through resistors. The wiper setting advances once per button press up to 250ms. Maxim’s SmartWiper control circuitry allows the wiper to advance at a 4Hz rate after holding the button for approximately 250ms. After 500ms, the wiper moves at an 8Hz rate. After 1s, the rate increases to 11Hz (see Table 2). The SmartWiper control eliminates the need for a microcomputer to increase the wiper transition rate. The MAX5486 MODE input toggles the part between volume and balance-control modes. The UP/BALL and DN/BALR inputs control the wiper according to the selected mode. MODE is internally pulled high with a resistor to VLOGIC. Volume Control In volume-control mode, the MAX5486’s wipers move simultaneously, maintaining the balance separation between each wiper (Figure 2a). When either wiper reaches the maximum tap position (position closest to H_), further commands to increase the volume are ignored. Balance separation is maintained in the maximum volume configuration (Figure 2b). When either wiper reaches the minimum tap position (position closest to L_), further commands to decrease the volume adjust the other wiper until it also reaches the minimum tap position (Figure 2c). Increasing the volume from this minimum position restores the original balance separation of the wipers (Figure 2d). 8 DN MAX5486 MOMENTARY CONTACT SPST PUSHBUTTONS GND Figure 1. Pushbutton Interface Table 1. Wiper Position and Attenuation POSITION ATTENUATION (dB) 0 0 1 2 2 4 3 6 4 8 M M 30 60 31 62 32 (mute) > 90 Table 2. Wiper Action vs. Pushbutton Contact Duration CONTACT DURATION WIPER ACTION t ≤ 16ms No motion. 16ms < t ≤ 250ms Wiper changes position once. 250ms < t ≤ 500ms SmartWiper begins. Wiper changes position at a rate of 4Hz. 500ms < t ≤ 1000ms Wiper changes position at a rate of 8Hz. t > 1000 ms Wiper changes position at a rate of 11Hz. _______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface MAX5486 BALANCE SEPARATION MAINTAINED H_ WR WL WR WL PRESS UP TWICE WR WL WR WL PRESS DN ONCE WR WL (2a) L_ NO CHANGE H_ PRESS UP ONCE WR WL WR WL PRESS UP ONCE (2b) L_ H_ WR WL PRESS DN ONCE WR WL PRESS DN ONCE TO 2d (2c) L_ ORIGINAL BALANCE SEPARATION MAINTAINED H_ WR WL FROM 2c PRESS UP ONCE WR WL PRESS UP ONCE WR WL (2d) L_ Figures 2a–2d. Volume-Control Operation When both wipers are in the tap 31 position (-62dB attenuation), further commands to DN/BALR place the wipers in the mute position (see Table 1). UP/BALL or MUTE pulses return the wipers to tap 31. Balance Control In balance-control mode, the MAX5486 adjusts the balance between the right and left channels while maintaining the set volume. For example, if the volume of the right channel equals the volume of the left channel, forcing the balance towards the left channel increases the attenuation of the right channel (Figure 3a). If the left channel is at a higher attenuation than the right channel, adjusting the balance to the left channel moves the left channel’s wiper up to the same wiper position as the right channel before it was attenuated (Figure 3b). Click-and-Pop Suppression The click-and-pop suppression feature reduces the audible noise (clicks and pops) that results from wiper transitions. The MAX5486 minimizes this noise by allowing the wiper to change position only when VH = VL (zero crossing) or after the zero crossing timeout (126ms). Each wiper has its own suppression and timeout circuitry. The MAX5486 changes wiper position when VH = VL, or after 32ms, whichever occurs first (see Figures 4a and 4b). The suppression circuitry monitors left and right channels separately. In volume-control mode, when the first _______________________________________________________________________________________ 9 MAX5486 Stereo Volume Control with Pushbutton Interface VOLUME LEVEL MAINTAINED BALANCE SHIFTS TO WL VOLUME LEVEL IS SET H_ WR WL PRESS BALL ONCE WR WL PRESS BALL ONCE WR WL (3a) L_ H_ VOLUME LEVEL MAINTAINED BALANCE SHIFTS TO WL VOLUME LEVEL IS SET BY WR WR WL PRESS BALL ONCE WR WL PRESS BALL ONCE WR WL (3b) L_ Figures 3a and 3b. Balance-Control Operation wiper changes position, the second wiper has 126ms to change or it changes automatically. Power-On Reset The power-on comparators monitor (VDD - VSS) and (VLOGIC - GND). A power-on reset is initiated when either of the supplies is brought back to the normal operating voltage. The power-on reset feature sets both wipers to -12dB. The wipers initially wake up in mute mode (-90dB) and move to the -12dB position when VH = VL to eliminate clicks and pops during power-up. With DC inputs at VH and VL, the wipers move after exceeding the timeout period. A power-on reset places the MAX5486 in volume-control mode. Shutdown (SHDN) Upon entering shutdown, the MAX5486 stores the last wiper settings. The wipers move to the L_ end of the resistor string when VH = VL to eliminate clicks and pops during shutdown. With DC inputs at VH and VL, the wipers move after exceeding the timeout period. Exiting shutdown restores the wipers to their previous settings. Shutdown also turns off all the LED indicators to save power. Mute Function (MUTE) The MAX5486 features a mute function input, MUTE. Successive low pulses on MUTE toggle its setting. Activating the mute function forces both wipers to maximum attenuation (-90dB typ). Deactivating the mute 10 function returns the wipers to their previous settings. MUTE is internally pulled high with a resistor to VLOGIC. When both wipers are in the tap 31 position (-62dB attenuation) further commands to lower the volume place the wipers in the mute position (see Table 1). Mode Indicator (MODEIND) The open-drain MODEIND indicates volume-control mode or balance-control mode for the MAX5486. Connect MODEIND to an LED with a series resistor to VLOGIC. When the LED is on, the MAX5486 is in balance-control mode. When the LED is off, the MAX5486 is in volume-control mode. See the Mode Control (MODE) section for more detail on switching between modes. Level Indicator LEDs The MAX5486 includes five indicator LED drivers to display the current wiper settings in either volume or balance mode. The LED indicators are enabled by connecting a 1MΩ resistor between LEDIND4 and VLOGIC. Connect the LEDIND_ outputs to the LEDs and to VLOGIC through a series resistor as shown in the Typical Operating Circuit. Connect LEDIND_ outputs to GND when LED indicator drivers are not used. In volume-control mode, all LEDs are off when the wipers reach the highest attenuation levels (mute). All LEDs are on at the lowest attenuation levels (0dB). ______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface MAX5486 Table 3. LED Settings in Volume Mode VOLUME POSITION VOLUME LED OUTPUTS ( 1 = LED IS ON) LED0 LED1 LED2 LED3 LED4 0dB to -8dB 1 1 1 1 1 -10dB to -18dB 1 1 1 1 0 -20dB to -28dB 1 1 1 0 0 -30dB to -38dB 1 1 0 0 0 -40dB to -52dB 1 0 0 0 0 -54dB to mute (-90dB) 0 0 0 0 0 Table 3 shows the LED display as the wipers transition through various attenuation levels. A PWM circuit interpolates the high-resolution 32 steps between the five LEDs over the volume range from 0dB to -54dB. This feature provides visible indication for the attenuation levels from 0dB to -54dB. For example, LED4 brightness level decreases progressively with each -2dB step from 0dB to -8dB. PWM is disabled in the range -56dB to mute. In balance-control mode, only one LED is on at a time to indicate the current balance setting. Figure 5 shows the LEDs display for the current balance setting. When LED2 is on, the display indicates that the channels are centered or balanced at a set volume level. When LED4 turns on, the balance shifts completely toward the right channel and the left channel becomes fully attenuated. The MAX5486 does not respond to any logic input until the blocking period ends. If multiple-control buttons are pressed, all wiper-control connections must be released before the device responds to further commands. Applications Information The Typical Operating Circuit shows a typical volume/ balance application circuit using the MAX5486 in a single-supply configuration. The internally generated BIAS voltage eliminates the need for external op amps, and the wipers have internal low-power buffers for low distortion. Connect the W_ outputs of the MAX5486 to the left and right inputs of a stereo audio amplifier, such as the MAX9761. The pushbutton potentiometers attenuate the input signals. Use the MODE input to switch between volume-control and balance-control modes. Multiple Button Pushes The MAX5486 does not respond to simultaneous button pushes. Additionally, a 16ms blocking period affects all other inputs when releasing any input that was forced low. ______________________________________________________________________________________ 11 MAX5486 Stereo Volume Control with Pushbutton Interface SWITCH SWITCH CONTACT CONTACT IS BOUNCING IS STABLE USER PRESSES PUSHBUTTON SWITCH CONTACT IS BOUNCING READY TO ACCEPT ANOTHER KEYPRESS 1 DN OR UP INPUT ACCEPTED 0 tHPW tIPW tWS DEBOUNCE BY WAITING FOR STABLE HIGH, tHPW WAIT FOR DEBOUNCE BY FIRST ZERO WAITING FOR CROSSING, tWS STABLE LOW, tIPW VH VL WIPER MOVES HERE WIPER MOTION 2dB STEPS Figure 4a. Wiper Transition Timing Diagram—Suppression Circuitry Active 12 ______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface SWITCH CONTACT IS BOUNCING MAX5486 SWITCH SWITCH CONTACT CONTACT IS BOUNCING IS STABLE READY TO ACCEPT ANOTHER KEYPRESS 1 INPUT ACCEPTED 0 tHPW tWS tIPW WAIT FOR DEBOUNCE BY FIRST ZERO WAITING FOR CROSSING OR STABLE LOW, TIMEOUT, tWS tIPW DEBOUNCE BY WAITING FOR STABLE HIGH, tHPW VH VL WIPER MOVES HERE (tIPW + tWS) 2dB STEPS Figure 4b. Wiper Transition Timing Diagram—Timeout FULL L L + 12 L+6 PB PRESS (CHANNEL L) LED0 ON LED1 ON R+6 CENTERED LED2 ON R + 12 FULL R PB PRESS (CHANNEL R) LED3 ON LED4 ON Figure 5. LED Settings in Balance Mode ______________________________________________________________________________________ 13 Stereo Volume Control with Pushbutton Interface MAX5486 Functional Diagram VDD VDD HR BIAS BIAS GENERATOR BIASCAP MAX5486 VSS WR LR MODEIND LEDIND4 LEDIND3 LED DRIVERS HL LEDIND2 LEDIND1 LEDIND0 WL SWITCH CONTROL, CLICK-AND-POP SUPPRESSION LL UP/BALL 14 VLOGIC DEBOUNCE, TIMEOUT, ACCELERATION DN/BALR MODE MUTE SHDN GND VSS ______________________________________________________________________________________ Stereo Volume Control with Pushbutton Interface Chip Information PROCESS: BiCMOS TOP VIEW + VLOGIC 1 24 GND DN/BALR 2 23 MODEIND UP/BALL 3 22 LEDIND4 MUTE 4 21 LEDIND3 MODE 5 MAX5486 20 LEDIND2 SHDN 6 19 LEDIND1 N.C. 7 18 LEDIND0 HR 8 17 HL LR 9 16 LL WR 10 15 WL BIAS 11 14 VSS BIASCAP 12 13 VDD TSSOP ______________________________________________________________________________________ 15 MAX5486 Pin Configuration 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.) TSSOP4.40mm.EPS MAX5486 Stereo Volume Control with Pushbutton Interface PACKAGE OUTLINE, TSSOP 4.40mm BODY 21-0066 G 1 1 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. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products. Inc.