DA6116.001
27 February, 2009
GENERAL DESCRIPTION
Operating modes
When power is first applied, power-on reset initializes control registers and sets MAS6116 into mute state,
ignoring the state of the XMUTE pin. The activation of the device requires that XMUTE pin is high and a control
byte with a greater than the default value (00HEX) is written in the gain register. It is possible to return to the mute
state either by setting XMUTE pin low or writing zero (00HEX) to the gain register. Setting the XMUTE pin low will
mute both channels. Setting the XMUTE pin back high will return the channels to previously written gain values.
The zero cross detector function is used when entering and returning from the mute state to prevent large
transients in the output signal (see chapter Changing the gain of the channels).
The device has a special test mode register, which is used only for internal testing of the device. It is strongly
recommended not to change the default value (00HEX) of the test register during normal operation. For device
testing the XMUTE pin is bi-directional. When the test register bit 1 is set to high, XMUTE pin is in output mode. In
the test mode internal signals can be directed to the XMUTE pin. Note: In the test mode both analog outputs are
in mute state and the device will not allow new gain values to be written in the gain registers. An exception to this
is the force latch command specified in table Test Register CR5 Description, which can be used to instantly
change the gain of both channels. This function is intended to be used in the test mode only, and it is
recommended to use the commands specified in Register Description to instantly change the channel gains.
Changing the gain of the channels
When a new gain value is written to the gain register the device will activate the zero crossing detection and delay
generator for the selected channel. MAS6116 will wait until a rising edge of the input signal is detected to change
the gain value. This is done to ensure that no audible clicks are produced to the output signal during the gain
change operation. The zero cross detection circuit has also a timeout delay generator that will force the gain
change. The delay generator generates a typical delay of 22 ms.
If a new gain value is written before the previous write operation has finished, the previously written value will be
overwritten and will not be set to the output. If it is desired that each gain value is set to the output, it is
recommended to read the status bit from the write operation status register (CR6) or wait for at least 30 ms before
the next gain change instruction.
Both channels can be programmed independently with separate commands. In this case the gain values will be
set to the output in the order of writing. Both channels can also be programmed to the same value by writing only
one instruction (see the Register Description on page 7).
Note: Due to the input signal dependency of the zero cross detection circuits the order of the gain changes may
differ from the order of writing to the registers if the input signals to the channels are different. This applies to all
instructions that use the zero cross detection and timeout functions, i.e. instructions that are not labeled as
“instant” in the register description.
The new gain value can be set instantly to the output by using the instant gain change function. By using this
command function the gain is set to the output instantly after the write operation has finished, without waiting a
zero cross to occur in the input signal or a delay to pass. The gains can be set independently to both channels
using different commands, or both channels can be set to the same gain value by using a single command. Using
the instant gain change function to change the gain value in larger than 0.5 dB steps may produce audible clicks
to the output signal.
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MAS [ MICRO ANALOG SYSTEMS ]
