R262 datasheet(20/28 Pages) ONSEMI

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BelaSigna R262

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I2C Command Handler

The BelaSigna R262 ROM application contains an

I2C−based command and control interface, allowing many

aspects of the chip’s operation and hardware configuration

to be controlled via I2C. This I2C interface is the

recommended way to control the chip and to configure the

application at run−time. The default I2C address of

BelaSigna R262 is 0x61. The I2C interface protocol is fully

supported by the SignaKlara Device Utility (SKDU) and

other software tools provided by ON Semiconductor.

For more information on the I2C interface, please refer to

the I2C interface section of this document, as well as the

BelaSigna R262 Communications and Configuration

Guide.

Reset

BelaSigna R262 can be forced to execute a

power−on−reset by pulling the NRESET pin to ground for

at least 100 ns. NRESET is not available on the 26−ball

WLCSP package.

System Monitoring

The application software within BelaSigna R262 is

equipped with a few blocks that monitor system sanity. A

watchdog timer is used to ensure proper execution of the

signal processing application. It is always active and is

periodically acknowledged as a check that the application is

still running. Once the watchdog times out, a hardware

system reset will occur. System sanity is also monitored by

the clock detection mechanism; the chip will automatically

enter Sleep mode if it is in Active or Bypass mode and it

detects that the external clock source (the signal on

EXT_CLK) is stopped. In this case, the system will only exit

Sleep mode when it detects that the external clock source has

been restored or a reset occurs.

The power supply blocks of the system also monitor for

minimum supply voltages as part of the power supervision

strategy, as described in the Power Management section.

Analog Blocks

Input Stages

The BelaSigna R262 analog audio input stage is shown in

Figure 10. The input stage is comprised of two individual

channels. There are four configurable aspects of each

channel – input multiplexing, preamplifier gain, filtering

and line out. The input multiplexing allows one input to be

selected from any of the four possible inputs and then routed

to the input of the preamplifier. Each preamplifier can be

configured for bypass or gain values of 12 to 30 dB in 3 dB

steps. The filters can be configured as well; the DC removal

high−pass filter can be bypassed, or set to a cut−off

frequency of 5 Hz, 10 Hz or 20 Hz (default). The low−pass

filter can be either enabled with a 20 kHz cut−off frequency

(default), or bypassed. The lineout selection allows the

preamplifier outputs to be routed back out via the auxiliary

audio input pins. Note that the AI1/LOUT1 pin is not

available on the 26−ball WLCSP package option.

Two analog−to−digital converters then convert the analog

signals into the digital domain. The ADCs are running at a

sampling rate of 21.3 kHz in Active mode and 16 kHz in

Bypass mode. The sampling rate can potentially be changed

using the I2C interface. Changing the sampling rate in

Active mode will cause the noise cancellation algorithm to

stop operating properly, so this should not be done; however,

the sampling rate in Bypass mode could be changed to other

values. Contact your local technical support for more

information.

Input signal amplitudes can also be adjusted in the digital

domain; digital gain for both converted signals can be

adjusted by using I2C commands.

The ROM−based application pre−configures all these

parameters in the input stage such that the algorithm

operates properly. These parameters can be changed using

the I2C interface, but careful design consideration should be

taken when doing so, as this could alter the performance of

the algorithm.

The AI3 pin is multiplexed with the microphone power

supply (VMIC). The default mode for the microphone bias

is to be used as a 2 V power supply. Consequently, any

application that plans to use the AI3 input pin or the LOUT0

functionality has to change the VMIC setting to high−

impedance mode, such as the pin can be properly used as an

analog input or a line−out.

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