Controller for Audio Volume and Balance Features Rotary-Encoder Interface to Eliminate Microcontroller and Save Cost
| Note to the Editor: The MAX5440 controller
provides audio designers the simplest
rotary-control interface for volume and balance.
The MAX5440 also eliminates the need for a
microcontroller, GPIO, or external debounce
circuitry to control the interface of the
devices. Integrated wiper buffers allow the
device to connect directly to the power amplifier
of the audio output. Balance and volume are
controlled separately for audio applications. |
SUNNYVALE, CA-May 3, 2006-Maxim Integrated
Products (NASDAQ: MXIM) introduces the MAX5440
controller for audio volume and balance. A
debounced rotary-encoder interface directly
controls volume and balance. No external
microcontroller, GPIO, or debounce circuitry is
required for the control interface. An integrated
algorithm separately controls volume and balance.
Buffered wiper outputs allow the MAX5440 to
connect directly to the audio circuit's power
amplifier. An integrated bias generator provides
the necessary (VDD - Vss)/2 voltage for unipolar
input signals, eliminating the need for costly
external bias circuitry and saving board space.
The MAX5440's rotary-encoder interface uses
grey-scale coding to move the wiper up and down
the 40k resistor string. A mute function
sets all wipers to maximum attenuation when
activated, and returns the wipers to their
previous position when deactivated. A shutdown
feature sets the wipers to maximum attenuation
and disconnects H_ from the signal path when
activated. Deactivating shutdown returns the
wipers to their previous position. Integrated
glitch suppression circuitry ensures "clickless"
switching between wiper transitions. The MAX5440
also provides an open-drain LED-mode indicator
that specifies volume or balance-control mode.
Separate LED outputs indicate volume level or
balance shift, depending on the operating mode.
Available in a 24-pin SSOP package, this device
is significantly smaller than the mechanical
potentiometers and associated external circuitry
needed to perform the same tasks. The MAX5440
contains two 40k resistor strings that
offer ratiometric and end-to-end temperature
coefficients as low as 5ppm/°C and
35ppm/°C, respectively. This audio
controller saves power by operating from a +2.7V
to +5.5V single supply or ±2.7V, and by requiring
less than 0.5µA in standby. Prices start
at $1.47 (1000-up, FOB USA).
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