Document No. 002-14949 Rev. *E
Page 36 of 113
PRELIMINARY
CYW43353
7.3 I
2
S Interface
The CYW43353 supports two independent I
2
S digital audio ports. The I
2
S signals are:
❐
I
2
S clock: I
2
S SCK
❐
I
2
S Word Select: I
2
S WS
❐
I
2
S Data Out: I
2
S SDO
❐
I
2
S Data In: I
2
S SDI
I
2
S SCK and I
2
S WS become outputs in master mode and inputs in slave mode, while I
2
S SDO always stays as an output. The
channel word length is 16 bits and the data is justified so that the MSB of the left-channel data is aligned with the MSB of the I
2
S bus,
per the I
2
S specification. The MSB of each data word is transmitted one bit clock cycle after the I
2
S WS transition, synchronous with
the falling edge of bit clock. Left-channel data is transmitted when I
2
S WS is low, and right-channel data is transmitted when I
2
S WS
is high. Data bits sent by the CYW43353 are synchronized with the falling edge of I2S_SCK and should be sampled by the receiver
on the rising edge of I2S_SSCK.
The clock rate in master mode is either of the following:
48 kHz x 32 bits per frame = 1.536 MHz
48 kHz x 50 bits per frame = 2.400 MHz
The master clock is generated from the input reference clock using a N/M clock divider.
In the slave mode, any clock rate is supported to a maximum of 3.072 MHz.
7.3.1 I
2
S Timing
Note:
Timing values specified in
are relative to high and low threshold levels.
Table 11. Timing for I
2
S Transmitters and Receivers
Transmitter
Receiver
Notes
Lower LImit
Upper Limit
Lower Limit
Upper Limit
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Max.
Clock Period T
T
tr
–
–
–
T
r
–
–
–
1
Master Mode: Clock generated by transmitter or receiver
HIGH t
HC
0.35T
tr
–
–
–
0.35T
tr
–
–
–
2
LOWt
LC
0.35T
tr
–
–
–
0.35T
tr
–
–
–
Slave Mode: Clock accepted by transmitter or receiver
HIGH t
HC
–
0.35T
tr
–
–
–
0.35T
tr
–
–
3
LOW t
LC
–
0.35T
tr
–
–
–
0.35T
tr
–
–
Rise time t
RC
–
–
0.15T
tr
–
–
–
–
4
Transmitter
Delay t
dtr
–
–
–
0.8T
–
–
–
–
5
Hold time t
htr
0
–
–
–
–
–
–
–
Receiver
Setup time t
sr
–
–
–
–
–
0.2T
r
–
–
6
Hold time t
hr
–
–
–
–
–
0
–
–