adau1961 Analog Devices, Inc., adau1961 Datasheet - Page 24

• Manufacturer Part Number: adau1961
• Description: Stereo, Low Power, 96 Khz, 24-bit Audio Codec With Integrated Pll Adau1961
• Manufacturer: Analog Devices, Inc.

ADAU1961
CLOCKING AND SAMPLING RATES
CORE CLOCK
Clocks for the converters and the serial ports are derived from
the core clock. The core clock can be derived directly from
MCLK or it can be generated by the PLL. The CLKSRC bit (Bit
3 in Register R0, Address 0x4000) determines the clock source.
The INFREQ[1:0] bits should be set according to the expected
input clock rate selected by CLKSRC; this value also determines
the core clock rate and the base sampling frequency, f
For example, if the input to CLKSRC = 49.152 MHz (from
PLL), then
The PLL output clock rate is always 1024 × f
control register automatically sets the INFREQ[1:0] bits to
1024 × f
INFREQ[1:0] frequency should be set according to the MCLK
pin clock rate and the desired base sampling frequency.
Table 11. Clock Control Register (Register R0, Address 0x4000)
Bits
3
[2:1]
0
MCLK
INFREQ[1:0] = 1024 × f
f
S
= 49.152 MHz/1024 = 48 kHz
S
Bit Name
CLKSRC
INFREQ[1:0]
COREN
when using the PLL. When using a direct clock, the
R1: PLL CONTROL REGISTER
÷ X
× (R + N/M)
Settings
0: Direct from MCLK pin (default)
1: PLL clock
00: 256 × f
01: 512 × f
10: 768 × f
11: 1024 × f
0: Core clock disabled (default)
1: Core clock enabled
S
S
S
S
(default)
S
CLKSRC
CONTROL REGISTER
S
, and the clock
R0: CLOCK
768 ×
256 ×
INFREQ[1:0]
S
.
f
f
S
S
, 1024 ×
, 512 ×
Figure 29. Clock Tree Diagram
Rev. 0 | Page 24 of 76
f
S
f
S
,
CLOCK
CORE
CONTROL 0 REGISTER
SAMPLING RATES
The ADCs, DACs, and serial port share a common sampling
rate that is set in Register R17 (Converter Control 0 register,
Address 0x4017). The CONVSR[2:0] bits set the sampling rate
as a ratio of the base sampling frequency.
Table 12 and Table 13 list the sampling rate divisions for
common base sampling rates.
Table 12. 48 kHz Base Sampling Rate Divisions
Base Sampling
Frequency
f
Table 13. 44.1 kHz Base Sampling Rate Divisions
Base Sampling
Frequency
f
S
S
f
S
R17: CONVERTER
= 48 kHz
= 44.1 kHz
/0.5, 1, 1.5, 2, 3, 4, 6
CONVSR[2:0]
Sampling Rate Scaling
f
f
f
f
f
f
f
Sampling Rate Scaling
f
f
f
f
f
f
f
S
S
S
S
S
S
S
S
S
S
S
S
S
S
/1
/6
/4
/3
/2
/1.5
/0.5
/1
/6
/4
/3
/2
/1.5
/0.5
ADCs
DACs
Sampling Rate
48 kHz
8 kHz
12 kHz
16 kHz
24 kHz
32 kHz
96 kHz
Sampling Rate
44.1 kHz
7.35 kHz
11.025 kHz
14.7 kHz
22.05 kHz
29.4 kHz
88.2 kHz
INPUT/OUTPUT
SERIAL DATA
PORT