User's Manual

BT860
Datasheet
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18
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Table 16: PCM Burst Mode Specifications (Receive Only, Long-Frame Sync)
Reference Characteristics Min. Typ. Max. Unit
1
PCM bit clock frequency
- - 24 MHz
2
PCM bit clock LOW
20.8 - - ns
3
PCM bit clock HIGH
20.8 - - ns
4
PCM_SYNC setup
8 - - ns
5
PCM_SYNC_hold
8 - - ns
6 PCM_IN setup 8 - - ns
7
PCM_IN hold
8 - - ns
8.4. I
2
S Interface
The BT860 supports two independent I
2
S digital audio ports. The I
2
S interface supports both master and slave
modes. 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
BT860 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.