R261 datasheet(12/28 Pages) ONSEMI

12 / 28 page

BelaSigna R261

http://onsemi.com

Table 5. NON−CRITICAL SIGNALS

Pin Name

Description

Connection Guidelines

CAP0, CAP1

Internal charge pump −

capacitor connection

Place 100 nF capacitor very close to pins

I2C_SDA, I2C_SCL

I2C port

Keep as short as possible. Place pull−up resistors (10 k) to VDDO

ALGO_CTRL,

SLEEP_CTRL

Control GPIOs

(Multiplexed with SPI port)

Not critical when used as GPIO

CONFIG_SEL, ATT_SEL

Low−speed A/D converters

(Multiplexed with SPI port)

Not critical when used as LSAD

BOOT_SEL

Control GPIO

Not critical

SPI_CLK, SPI_CS,

SPI_SERO, SPI_SERI

Serial peripheral interface port

(Multiplexed with LSAD and

GPIOs)

Keep away from analog input lines when used as SPI signals

NRESET

Reset

Not critical

Leave unconnected if unused

DEBUG_RX, DEBUG_TX

Debug Port

Not critical

If possible, connect to test points

RESERVED

Reserved pin

Leave unconnected

VBATRCVR

Output driver power supply

If the output driver is being used:

− Place a separate 4.7 mF (min. 2.2 mF) decoupling capacitor

close to pin

− Connect positive terminal of capacitor to VBAT & VBATRCVR

− Connect negative terminal of capacitor to VSSRCVR

If the analog outputs or the DMIC output are being used:

− Decoupling capacitor is not required

− Connect VBATRCVR to VDDA

Audio Inputs

The audio input traces should be as short as possible. The

input impedance of each audio input pad (e.g., MIC0, AI1,

MIC2, AI3) is high (approximately 500 k

W with PAs

enabled); therefore a 10 nF capacitor is sufficient to

decouple the DC bias. This capacitor and the internal

resistance form a first−order analog high pass filter whose

cut−off frequency can be calculated by f3dB (Hz) = 1/(R x C

x 2

π), which results in ~30 Hz for a 10 nF capacitor. This 10

nF capacitor value applies when the preamplifier is being

used, in other words, when a non−unity gain is applied to the

signals; for MIC0 and MIC2, the preamplifier is enabled by

the ROM−based application. When the preamplifier is

by−passed, the impedance is reduced; hence, the cut−off

frequency of the resulting high−pass filter could be too high.

In such a case, the use of a 30−40 nF serial capacitor is

recommended. In cases where line−level analog inputs

without DC bias are used, the capacitor may be omitted for

transparent bass response. ON Semiconductor recommends

avoiding SMT capacitors with X7R dielectric, as it is known

to be microphonic, sensitive to temperature and increase

THD. NPO or COG dielectric capacitors have demonstrated

good performance.

BelaSigna R261 provides a microphone power supply

(VMIC) and ground (VSSA). In case VMIC cannot be used

for PCB routing issues, the power supplies VREG (1.0 V) or

VDDA (2.0 V) can alternatively be used. Keep audio input

traces strictly away from output traces.

Audio outputs must be kept away from microphone inputs

to avoid cross−coupling.

Audio Outputs

The audio output traces should be as short as possible. The

trace length of the two signals should be approximately the

same to provide matched impedances.

Recommendation for Unused Pins

Table 6 shows the connection details for each pin when

they are not used.

Table 6. UNUSED PIN RECOMMENDATIONS

Signal Name

Connection Guidelines

A_OUT0

Do not connect

A_OUT1

Do not connect

AI3/VMIC/LOUT0

Do not connect when con-

figured as VMIC (default)

Connect to VSSA otherwise

AI1/LOUT1

Connect to VSSA

DMIC_OUT

Do not connect

SPI_SERO/ALGO_CTRL

Do not connect

SPI_SERI/SLEEP_CTRL

Do not connect

NRESET

Do not connect

R261 Datasheet(PDF) 12 Page - ON Semiconductor

R261 Datasheet(HTML) 12 Page - ON Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL