Datasheet

Detailed Description
The MAX5486 dual 40kΩ logarithmic taper digital vol-
ume 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 potenti-
ometers.
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
V
LOGIC
. The MAX5486 powers up in volume-control
mode. Leave unconnected or connect to V
LOGIC
if bal-
ance 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 V
LOGIC
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 microcom-
puter 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 V
LOGIC
.
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).
Figure 1. Pushbutton Interface
Table 1. Wiper Position and Attenuation
Table 2. Wiper Action vs. Pushbutton
Contact Duration
POSITION ATTENUATION (dB)
0 0
1 2
2 4
3 6
4 8
… …
30 60
31 62
32 (mute) > 90
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.
GND
MOMENTARY
CONTACT
SPST
PUSHBUTTONS
DN
V
LOGIC
UP
MAX5486
MAX5486 Stereo Volume Control with Pushbutton
Interface
www.maximintegrated.com
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