MAX5440

The MAX5440 dual, 40k logarithmic taper volume control features a debounced up/down interface for use with a simple rotary encoder without using a microcontroller (C). Each potentiometer has 32 log-spaced tap points with a buffered wiper output and replaces mechanical potentiometers. A mode-indicator LED output specifies volume or balance control. 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. Five integrated LED drivers indicate volume level or balance settings, depending on the status of the mode indicator. The MAX5440 provides a nominal temperature coefficient of 35ppm/°C end-toend and 5ppm/°C, ratiometrically. The MAX5440 includes debounced pushbutton inputs for mute and mode. The mute input allows a single pushbutton to change between volume control and the -90dB (typ)mute setting. A click-and-pop suppression feature minimizes the audible noise generated by wiper transitions. The mode input toggles between volume and balance control. The MAX5440 is available in a 24-pin SSOP package and is specified for operation over the -40°C to +85°C extended temperature range.

The features of MAX5440 can be summarized as (1)logarithmic taper volume control with (31)2dB steps; (2)low-power wiper buffers provide 0.003% THD; (3)single +2.7V to +5.5V or Dual ±2.7V supply voltage operation; (4)low 0.5A shutdown supply current; (5)integrated bias voltage generator; (6)five-segment LED volume/balance indicator; (7)clickless switching; (8)40k end-to-end fixed resistance value; (9)mute function toggles to -90dB (typ); (10)power-on reset to -12dBFwiper position.

The absolute maximum ratings of MAX5440 are (1)SHDN, MUTE, RENCODEA, RENCODEB, and MODE to GND: -0.3V to (VLOGIC + 0.3V); (2)H_, L_, and W_ to VS: -0.3V to (VDD + 0.3V); (3)LEDIND_, MODEIND to GND: -0.3V to (VLOGIC + 0.3V); (4)MIDBIAS, BIAto VSS: (VS0.3V)to (VDD + 0.3V); (5)VLOGIC to GND: -0.3V to (VDD + 0.3V); (6)VDD to GND: -0.3V to +6V; (7)VDD to VSS: -0.3V to +6V; (8)VSto GND: -3V to +0.3V; (9)input and output latchup immunity: ±200mA; (10)continuous power dissipation (TA = +70°C)24-pin SSOP (derate 12.3mW/°C above +70°C): 987.7mW; (11)operating temperature range: -40°C to +85°C; (12)junction temperature: +150°C; (13)storage temperature range: -60°C to +150°C; (14)lead temperature (soldering, 10s): +300°C.