Ad73311Ar Codec (Using A 3 Volt Supply) - Digital Voice Systems AMBE-2000 Interface Manual

AD73311AR codec (using a 3 volt supply)

It may be desirable for the AD73311 AD/DA converter to be configured for a 3-volt supply
voltage instead of a 5-volt supply voltage. The diagram and configuration procedure below
outline the details necessary in order to send alternate configuration words to the CODEC.
U1
27
CODEC_RX_CLK
33
CODEC_TX_CLK
37
CODEC_TX_STRB
29
CODEC_RX_STRB
31
CODEC_RX_DATA
41
CODEC_TX_DATA
AMBE-2000
U3
SCLK
FS
SDO
DSP/Microcontroller
Figure 2: The AMBE-2000™ or AMBE-2020™ Vocoder with the AD73311 Configured for 3-volt operation.
The objective of this circuit is to tri-state the output of the AMBE-2000 CODEC_TX_DATA. This
allows the DSP or Microcontroller to communicate with the AD73311 to send it the desired
configuration.
1. Configure the AMBE-2000 for operation with the AD73311 Codec. Set the CODEC_SEL
pins as shown.
CODEC_SEL [1-0] (pins 85,84) = 01,b
2. Hold the CODEC_TX_DATA lines on the AMBE-2000 in tri-state (in the circuit set the
SDI bit to 0,b) during power up.
3. While the AMBE-2000 lines are in tri-state, send the desired configuration words from
the DSP/Microcontroller/logic to the AD73311 (Reset timing constraints for the AD73311
must be met).
4. After sending the configuration words set the SDI Control bit to 1,b (SEE NOTE). This
sets the CODEC SDI line for normal operation with the AMBE-2000.
NOTE: The SDI Control bit must be set to 0 for approximately 365 msec following a hardware reset.
AMBE-2000™ and AMBE-2020™ Vocoder Chip Interface Applications Note
2 3
U4A
SN74AHC125
2 3
U5A
SN74AHC125
Page 2 of 4
U2
14 20 High
SCLK SE
17 15 16.384 MHz
SDOFS MCLK
18 3 3.3 Volts
SDIFS AVDD1
16 9
SDO AVDD2
19 12 3.3
SDI DVDD
Volts
AD73311AR
U8A
2 1
SDI
CONTROL
0/DSP
1/AMBE-2000
May 02