AN1836-AN21161 Analog Devices, AN1836-AN21161 Datasheet - Page 18

• Manufacturer Part Number: AN1836-AN21161
• Description: Interfacing the ADSP-21161 SIMD SHARC DSP to the AD1836 (24-bit/96 kHz) Multichannel Codec
• Manufacturer: Analog Devices

3.1 ADSP-21161 -
The ADSP-21161 is a new derivative of the ADSP-2116x SIMD SHARC family which is based on a .18 micron CMOS
process, and is a dual voltage part operating at a 1.8 volt core and 3.3 volt I/O. Since the ADSP-21161 is a dual voltage part,
the 5 volt signals that the AD1836 provides will damage the driver pins on the 21161 serial ports, which operate at 3.3 volts.
Two options are available to prevent this.
The AD1836's digital interface can optionally operate with a digital I/O supply voltage of 3.3 volts. Thus no level shifting is
required, making this the optimal method because no glue logic is required. To implement a glueless interface, the AD1836's
ODVDD can be connected to the system's 3.3 volt supply instead of the 5 volt supply. All AD1836 Digital I/O drivers will then
operate at 3.3 volts.
Another option is to level-shifting of all input signals from the AD1836. All SPORT output signals that are inputs to the
AD1836 do not need to be level shifted since the AD1836 will recognize 3.3 volts as a valid TTL high level.
In order to facilitate serial communications with the AD1836, the SPORT0 and SPORT2 pin connections are configured as
shown in Table 1 and Figure 9:
Figure 19. 21161 Optional Codec Interface with a 5 Volt Digital I/O Supply
ADSP-21161N Pin:
SCLK0, SCLK2
FS0
FS2 [TDV2] ( unconnected )
D0A
D2A
ADSP-21161
3.3 V Level Shifting Considerations
SCLK0
SCLK2
FS0
D0A
D2A
3.3V-to-5V
Translator
74LV125
Table 2.
Level
AD1836 Pin:
ABCLK
FSTDM (ALRCLK)
----------
ASDATA1
DSDATA1
ALRCLK
ABCLK
ASDATA1
DSDATA1
2
AD1836
Driven By:
----------
codec
DSP
codec
codec