Cirrus Logic CS42L51 - Manual (Page 39)

DS679F1 39
CS42L51
4.5.1 Slave
LRCK and SCLK are inputs in Slave Mode. The speed of the CODEC is automatically determined based
on the input MCLK/LRCK ratio when the Auto-Detect function is enabled. Certain input clock ratios will
then require an internal divide-by-two of MCLK* using either the MCLKDIV2 bit or the MCLKDIV2 stand-
alone control pin.
Additional clock ratios are allowed when the Auto-Detect function is disabled; but the appropriate speed
mode must be selected using the SPEED[1:0] bits.
4.5.2 Master
LRCK and SCLK are internally derived from the internal MCLK (after the divide, if MCLKDIV2 is enabled).
In Hardware Mode the CODEC operates in single-speed only. In Software Mode, the CODEC operates
in either quarter-, half-, single- or double-speed depending on the setting of the SPEED[1:0] bits.
Auto-Detect QSM HSM SSM DSM
Disabled
(Software
Mode only)
512, 768, 1024, 1536,
2048, 3072
256, 384, 512, 768,
1024, 1536
128, 192, 256, 384,
512, 768
128, 192, 256, 384
Enabled
1024, 1536, 2048*,
3072*
512, 768, 1024*, 1536* 256, 384, 512*, 768* 128, 192, 256*, 384*
*MCLKDIV2 must be enabled.
Table 3. MCLK/LRCK Ratios
ч 256
ч 128
ч 512
LRCK Output
(Equal to Fs)
Single
Speed
Quarter
Speed
Half
Speed
01
10
11
SCLK Output
ч 2
ч 1 0
1
MCLK
MCLKDIV2
ч 128 00
ч 4
ч 2
ч 8
Single
Speed
Quarter
Speed
Half
Speed
01
10
11
÷ 2 00
Double
Speed
Double
Speed
SPEED[1:0]
Figure 17. Master Mode Timing