MAX5486
Stereo Volume Control with Pushbutton
Interface
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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
potentiometers.
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 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 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 vol-
ume 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 main-
tained 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).
SmartWiper begins. Wiper
changes position at a rate of 4Hz.
of 8Hz.
of 11Hz.
