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19-0672; Rev 0; 11/06
Stereo Volume Control with Pushbutton Interface
General Description
The MAX5486 dual 40k 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 SmartWiperTM 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 40k per potentiometer. The MAX5486 is available in a 24-pin TSSOP package and is specified for operation over the -40C to +85C extended temperature range. 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 1A Shutdown Supply Current 40k End-to-End Fixed Resistance Value Small, 24-Pin TSSOP Package
Features
MAX5486
Ordering Information
PART MAX5486EUG+ TEMP RANGE -40C to +85C PINPACKAGE 24 TSSOP PKG CODE U24-1
+Denotes lead-free package.
Typical Operating Circuit
VDD VLOGIC
VLOGIC SHDN MODEIND VPEAK (VDD + VSS) / 2
MAX5486
1M
HR WR
RIGHT INPUT
Applications
Home-Theater Speakers Desktop Speakers Portable Media Players Docking Stations Automotive Rear-Seat Multimedia
LR
MAX9761 (VDD + VSS) / 2 LEDIND0 LEDIND1 LEDIND2 LEDIND3 HL LEDIND4 BIASCAP GND VSS MUTE UP/BALL DN/BALR MODE BIAS
LL WL
LEFT INPUT
VPEAK (VDD + VSS) / 2
SmartWiper is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
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.
Stereo Volume Control with Pushbutton Interface MAX5486
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 = +70C) 24-Pin TSSOP (derate 8.3mW/C above +70C) ..........657mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-60C to +150C Maximum Junction Temperature .....................................+150C Lead Temperature (soldering, 10s) .................................+300C
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 = 1F, BIAS = 3k 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 = +25C.) (Note 1)
PARAMETER RESISTOR LADDER End-to-End Resistance Absolute Tolerance Tap-to-Tap Tolerance VOLUME CONTROL VDD = 5V, VSS = 0, VH = (VDD / 2) + 1VRMS, VL = VDD / 2, 1kHz, tap at top, RL = 10k to VL = VDD / 2, 20Hz to 20kHz Total Harmonic Distortion Plus Noise THD+N VDD = 5V, VSS = 0, VH = (VDD / 2) + 1VRMS, VL = VDD / 2, 1kHz, tap at top, RL = to VL = VDD / 2, 20Hz to 20kHz VDD = 5V, VSS = 0, VH = (VDD / 2) + 1.5VRMS, VL = VDD / 2, 1kHz, tap at top, RL = 10k to VL = VDD / 2, 20Hz to 20kHz Channel Isolation Interchannel Matching Mute Attenuation Power-Supply Rejection Ratio H Terminal Capacitance L Terminal Capacitance End-to-End Resistance Temperature Coefficient Ratiometric Resistance Temperature Coefficient Bandwidth, -3dB fCUTOFF CW = 50pF PSRR CH CL SHDN = VDD Input referred, 217Hz, 100mVP-P on VDD VDD = +2.7V, VSS = -2.7V, VBIAS = GND 0.003 (Note 2) R 40 0.25 0.1 k dB dB SYMBOL CONDITIONS MIN TYP MAX UNITS
0.001
%
0.012 100 0.5 90 72 5 7 35 5 100 dB dB dB dB pF pF ppm/C ppm/C kHz
2
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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 = 1F, BIAS = 3k 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 = +25C.) (Note 1)
PARAMETER Output Noise WIPER BUFFER Output Voltage Swing Output Current Output Resistance DC Offset INTEGRATED BIAS GENERATOR Output Voltage Power-Supply Rejection Ratio Minimum Load Resistance Maximum Load Capacitance Output Resistance Noise Voltage Minimum Output Current CONTACT INPUTS (MUTE, MODE, UP/BALL, DN/BALR) Internal Pullup Resistor Single-Pulse Input Low Time Repetitive Input Pulse Separation Time Timeout Period Debounce Corner Frequency DIGITAL INPUTS (VLOGIC > 4.5V) VLOGIC > 4.5V Input High Voltage VIH VLOGIC < 4.5V VLOGIC > 4.5V Input Low Voltage VIL VLOGIC < 4.5V To GND for inputs with internal pullup resistors 5 fCLK = 1Hz to 40Hz, tap = -6dB -90 2.4 0.7 x VLOGIC 0.8 0.3 x VLOGIC 1 V V RPU tCPW tIPWS tWS Click-and-pop suppression inactive Internal analog filter Time required for a single pulse to cause an increment/decrement 16 1 126 10 42 k ms ms ms kHz ROBR 20Hz to 20kHz RL > 100k At 1kHz, 100mVP-P on VDD (VDD + (VDD + (VDD + VSS) / 2 VSS) / 2 VSS) / 2 - 20mV + 20mV 60 3 100 6 2.2 2 V dB k pF VRMS mA ROWB VOS VO RL = 3k to VBIAS 3 1 2 10 14 VDD 0.3V V mA mV SYMBOL eN CONDITIONS 20Hz to 20kHz, VH = VL = VDD / 2 = AC ground, tap = -6dB MIN TYP 2.2 MAX UNITS VRMS
MAX5486
Input Leakage Current Input Capacitance Digital Clock Feedthrough
A pF dB
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3
Stereo Volume Control with Pushbutton Interface MAX5486
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.5V, VSS = GND = 0, 2.7V (VDD - VSS) 5.5V, CBIASCAP = 1F, BIAS = 3k 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 = +25C.) (Note 1)
PARAMETER POWER SUPPLIES Positive Power Supply Negative Power Supply Supply-Voltage Difference Analog Supply Current Power-Up Time Logic Supply Voltage Logic Active Supply Current Logic Standby Supply Current (Note 3) Shutdown Current Shutdown Time/Return from Shutdown IDD tPU VLOGIC ILOGIC ILOGICSTBY ISHDN tSHDN VSS = 0 VLOGIC = VDD (Note 4) VDD = +5V, VSS = 0 VDD = +2.7V, VSS = -2.7V SHDN = 0, total of all supplies After 1st zero crossing 1 1 2.7 VDD VSS VSS = 0 VDD = +2.7V VDD - VSS (Note 3) 126 VDD 200 1 1 2.7 -2.7 5.5 0 5.5 1.4 V V V mA ms V A A A ms SYMBOL CONDITIONS MIN TYP MAX UNITS
LED INDICATORS (LEDIND0-LEDIND4, MODEIND) Output Low Voltage Maximum Output Leakage Current Output Capacitance VOL VLOGIC = 2.7V, ISINK = 10mA VLOGIC = 5V, ISINK = 10mA 10 3 0.4 0.2 V A pF
Note 1: Note 2: Note 3: Note 4:
Parameters are 100% production tested at +85C 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.
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Stereo Volume Control with Pushbutton Interface
Typical Operating Characteristics
(VDD = +5.0V, VSS = GND = 0, VLOGIC = +5.0, VH_ = VDD - 0.15V, VL_ = VDD / 2, CBIASCAP = 1F)
END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE
MAX5486 toc01
MAX5486
ATTENUATION vs. TAP POSITION
0 -10 ATTENUATION (dB) -20 -30 -40 -50 -60 -70 0 4 8 12 16 20 24 28 32 TAP POSITION 0.15 END-TO-END RESISTANCE CHANGE (%) 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25
VDD = VLOGIC = 5V VSS = GND = 0
-40
-15
10
35
60
85
TEMPERATURE (C)
WIPER SWITCHING TRANSIENT
MAX5486 toc03
WIPER-TO-END TERMINAL VOLTAGE vs. TAP POSITION
NOMINAL END-TO-END VOLTAGE (%VHL) 90 80 70 60 50 40 30 20 10 0 0 4 8 12 16 VWL 20 24 28 32 VHW
MAX5486 toc04
100 DN
5V/div
200mV/div WIPER TRANSITION FROM -2dB TO -4dB
40ms/div
TAP POSITION
FREQUENCY RESPONSE
MAX5486 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX5486 toc06
POWER-SUPPLY REJECTION RATIO
-30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 VDD = 5V 100mVP-P, VSS = GND VH_ = 5V, VL_ = 2.5V W_ SET TO -6dB
MAX5486 toc07
5
VH1 = 2.5V 1VRMS, VL1 = 2.5V W_ SET TO 0dB
100 10 1
0 RESPONSE (dB)
VDD = 5V VSS = GND VL_ = 2.5V W_ SET TO 0dB
-5 W_ SET TO -6dB -10 W_ SET TO -12dB -15 W_ SET TO -18dB -20 0.01 0.1 1 10 100 1000 FREQUENCY (kHz)
0.1 VH_ = 2.5V 1.5VRMS 0.01 0.001 VH_ = 2.5V 1VRMS
10k OR NO LOAD
10k OR NO LOAD 0.0001 0.01 0.1 1 FREQUENCY (kHz) 10 100
RESPONSE (dB)
THD+N (%)
0.01
MAX5486 toc02
0.1
1 FREQUENCY (kHz)
10
100
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5
Stereo Volume Control with Pushbutton Interface MAX5486
Typical Operating Characteristics (continued)
(VDD = +5.0V, VSS = GND = 0, VLOGIC = +5.0, VH_ = VDD - 0.15V, VL_ = VDD / 2, CBIASCAP = 1F)
LOGIC SUPPLY CURRENT vs. LOGIC SUPPLY VOLTAGE
MAX5486 toc08
LOGIC SUPPLY CURRENT vs. LOGIC INPUT VOLTAGE
MAX5486 toc09
ACTIVE LOGIC SUPPLY CURRENT vs. TEMPERATURE
VDD = VLOGIC = 5.5V
MAX5486 toc10
160 140 LOGIC SUPPLY CURRENT (A) ACTIVE CURRENT 120 100 80 60 40 STANDBY CURRENT 20 0 2.5 3.0 3.5 4.0 4.5 5.0
1000
150
LOGIC SUPPLY CUURENT (A)
148 ACTIVE ILOGIC (A)
146
100
144
142
10 5.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 LOGIC INPUT VOLTAGE (V) LOGIC SUPPLY VOLTAGE (V)
140 -40 -15 10 35 60 85 TEMPERATURE (C)
ACTIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5486 toc11
ACTIVE SUPPLY CURRENT vs. TEMPERATURE
VDD = VLOGIC = 5.5V UP = 0 ACTIVE SUPPLY CURRENT (mA) 1.5 NOISE (nV/Hz) 200 150 100 50 0 0 -40 -15 10 35 60 85 0.01
MAX5486 toc12
SPECTRAL NOISE DENSITY
MAX5486 toc13
2.0 ACTIVE SUPPLY CURRENT (mA) UP = 0 VLOGIC = 5.5V 1.5
2.0
300 250
1.0
1.0
0.5
0.5
0 0 1 2 3 4 5 6 SUPPLY VOLTAGE (V)
0.1
1 FREQUENCY (kHz)
10
100
TEMPERATURE (C)
CROSSTALK vs. FREQUENCY
-20 -40 CROSSTALK (dB) -60 -80 -100 -120 -140 -160 0.01 0.1 1 FREQUENCY (Hz) 10 100 2V/div VDD = 2.7V, VSS = -2.7V, VLOGIC = 5V W_SET TO 0dB, VHR = 1VRMS VLR = VLL = VHL = 0V
MAX5486 toc14
DIGITAL FEEDTHROUGH
MAX5486 toc15
0
50V/div
WIPER OUTPUT
PUSHBUTTON INPUT
500ns/div
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Stereo Volume Control with Pushbutton Interface
Pin Description
PIN 1 NAME VLOGIC FUNCTION Digital Logic Power Supply. Bypass VLOGIC to ground with a 0.1F capacitor as close as possible to the device. 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. 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. 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. 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. 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. Internally connected. Leave unconnected. Potentiometer R High Terminal Potentiometer R Low Terminal Potentiometer R Wiper Buffered Output Midbias Voltage Output. VBIAS = (VDD + VSS) / 2; connect a 100pF capacitor from BIAS to VSS. Bias Generator Bypass. Connect a 1F filter capacitor from BIASCAP to VSS. Analog Power Supply. Bypass VDD to ground with a 0.1F capacitor as close as possible to the device. Negative Power Supply. Bypass VSS to ground with a 0.1F capacitor as close as possible to the device. Connect to GND for single supply operation. Potentiometer L Wiper Buffered Output Potentiometer L Low Terminal Potentiometer L High Terminal LED Indicator Open-Drain Output 0-LED Indicator Open-Drain Output 4. Connect a 1M 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. 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. Ground
MAX5486
2
DN/BALR
3
UP/BALL
4
MUTE
5
MODE
6 7 8 9 10 11 12 13 14 15 16 17
SHDN N.C. HR LR WR BIAS BIASCAP VDD VSS WL LL HL
18-22
LEDIND0- LEDIND4
23 24
MODEIND GND
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Stereo Volume Control with Pushbutton Interface MAX5486
Detailed Description
The MAX5486 dual 40k 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.
VLOGIC
UP DN
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.
MOMENTARY CONTACT SPST PUSHBUTTONS
MAX5486
GND
Figure 1. Pushbutton Interface
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.
Table 1. Wiper Position and Attenuation
POSITION 0 1 2 3 4 M 30 31 32 (mute) ATTENUATION (dB) 0 2 4 6 8 M 60 62 > 90
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).
Table 2. Wiper Action vs. Pushbutton Contact Duration
CONTACT DURATION t 16ms 16ms < t 250ms 250ms < t 500ms 500ms < t 1000ms t > 1000 ms WIPER ACTION No motion. Wiper changes position once. SmartWiper begins. Wiper changes position at a rate of 4Hz. Wiper changes position at a rate of 8Hz. Wiper changes position at a rate of 11Hz.
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Stereo Volume Control with Pushbutton Interface MAX5486
H_ WR WL PRESS UP TWICE WR WL PRESS DN ONCE BALANCE SEPARATION MAINTAINED WR WL
(2a)
L_ NO CHANGE WR H_ WL PRESS UP ONCE WR WL PRESS UP ONCE WR WL
(2b)
L_ H_ WR WL PRESS DN ONCE WR WL PRESS DN ONCE WR WL TO 2d
(2c)
L_
H_ WR FROM 2c (2d) WL PRESS UP ONCE WR WL PRESS UP ONCE
ORIGINAL BALANCE SEPARATION MAINTAINED WR WL
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.
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
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
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Stereo Volume Control with Pushbutton Interface MAX5486
H_ VOLUME LEVEL IS SET WR WL PRESS BALL ONCE WR WL PRESS BALL ONCE VOLUME LEVEL MAINTAINED BALANCE SHIFTS TO WL WR WL
(3a)
L_ H_ VOLUME LEVEL IS SET BY WR WR WL PRESS BALL ONCE WR WL PRESS BALL ONCE
VOLUME LEVEL MAINTAINED BALANCE SHIFTS TO WL 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.
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.
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.
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 1M 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).
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
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Stereo Volume Control with Pushbutton Interface MAX5486
Table 3. LED Settings in Volume Mode
VOLUME POSITION 0dB to -8dB -10dB to -18dB -20dB to -28dB -30dB to -38dB -40dB to -52dB -54dB to mute (-90dB) VOLUME LED OUTPUTS ( 1 = LED IS ON) LED0 1 1 1 1 1 0 LED1 1 1 1 1 0 0 LED2 1 1 1 0 0 0 LED3 1 1 0 0 0 0 LED4 1 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.
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11
Stereo Volume Control with Pushbutton Interface MAX5486
USER PRESSES PUSHBUTTON 1 DN OR UP SWITCH SWITCH CONTACT CONTACT IS BOUNCING IS STABLE SWITCH CONTACT IS BOUNCING READY TO ACCEPT ANOTHER KEYPRESS
INPUT ACCEPTED 0 tHPW tIPW tWS
WAIT FOR DEBOUNCE BY FIRST ZERO WAITING FOR CROSSING, tWS STABLE LOW, tIPW
DEBOUNCE BY WAITING FOR STABLE HIGH, tHPW
VH
VL
WIPER MOVES HERE
WIPER MOTION
2dB STEPS
Figure 4a. Wiper Transition Timing Diagram--Suppression Circuitry Active
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Stereo Volume Control with Pushbutton Interface MAX5486
SWITCH SWITCH CONTACT CONTACT IS BOUNCING IS STABLE 1 SWITCH CONTACT IS BOUNCING READY TO ACCEPT ANOTHER KEYPRESS
INPUT ACCEPTED 0 tHPW tIPW tWS
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
PB PRESS (CHANNEL L) LED0 ON LED1 ON
L+6
R+6
R + 12 PB PRESS (CHANNEL R) LED3 ON LED4 ON
FULL R
CENTERED
LED2 ON
Figure 5. LED Settings in Balance Mode
______________________________________________________________________________________
13
Stereo Volume Control with Pushbutton Interface MAX5486
Functional Diagram
VDD
HR
VDD BIAS BIAS GENERATOR BIASCAP
MAX5486
VSS WR
LR MODEIND LEDIND4 HL LED DRIVERS LEDIND3 LEDIND2 LEDIND1 LEDIND0
WL
SWITCH CONTROL, CLICK-AND-POP SUPPRESSION DEBOUNCE, TIMEOUT, ACCELERATION VLOGIC
LL
UP/BALL
DN/BALR
MODE MUTE SHDN
GND
VSS
14
______________________________________________________________________________________
Stereo Volume Control with Pushbutton Interface
Pin Configuration
PROCESS: BiCMOS
TOP VIEW
VLOGIC 1 DN/BALR 2 UP/BALL 3 MUTE 4 MODE 5 SHDN 6 N.C. 7 HR 8 LR 9 WR 10 BIAS 11 BIASCAP 12 + 24 GND 23 MODEIND 22 LEDIND4 21 LEDIND3
Chip Information
MAX5486
MAX5486
20 LEDIND2 19 LEDIND1 18 LEDIND0 17 HL 16 LL 15 WL 14 VSS 13 VDD
TSSOP
______________________________________________________________________________________
15
Stereo Volume Control with Pushbutton Interface MAX5486
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.)
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 (c) 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products. Inc.
TSSOP4.40mm.EPS

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