Texas Instruments PurePath CC85XXDK, Руководство пользователя

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6.1 TLV320AIC3204 Codec
The codec on the CC85xx Headset board is the TLV320AIC3204 [3] from Texas Instruments Inc.
The TLV320AIC3204 is a stereo codec that supports six single-ended or 3 fully differential inputs.
On the CC85xx Headset board two input pins are used in single ended configuration (IN1L and
IN1R). The other inputs on the TLV320AIC3204 are unconnected. The TLV320AIC3204 has four
output pins. On the CC85xx Headset board two of these are used in single-ended configuration for
the headphone left and right. The other two outputs are unconnected.
The codec settings can be changed by changing the I
2
C configuration of the codec in the PurePath
Wireless Configurator. For more details on how to configure the codec, see the PurePath Wireless
Configurator help system. This is opened by selecting
Help->Configurator Help in the PurePath
Wireless Configurator. For more details about the I
2
C interface available on the CC85xx see the
CC85xx Family User’s Guide [5].
Audio tests have been conducted to verify codec performance. The codec has been run with local
LDO enabled, running at 1.77V. THD+N and SNR tests were conducted with a Rhode & Schwartz
UPA audio analyzer. The firmware used to measure the performance is the pre-programmed
firmware i.e., from the analog input of the Master to the analog output of the Slave. The volume on
the slave must be maximized to reproduce these measurements. The measured SNR performance
a-weighted at 1 kHz input is approximately 93 dB. The THD+N is measured to be approximately -
83 dB at an input voltage of 250 mVrms.
6.2 Power supply and charging of Li-ion battery
The CC85xx Headset board can be powered from the following sources
- Li-ion battery included in the kit
- USB interface, micro-USB type
Onboard the CC85xx Headset board is a single-chip charger and DC/DC converter i.e. BQ25015
[8]. The output voltage from its switch mode regulator is 2.15V which powers the other components
on the board (CC8531, CC2590 and TLV320AIC3204). The current consumption will vary with
different RF environments (more retransmission of data) as well as the volume of the audio.
However, the slave consumes in average approximately 22mA when using moderate audio
volume. This is measured at the battery (i.e. 81mW) with the firmware pre-programmed in
production. The master consumes approximately 31 mA measured at the battery. In powerdown
the CC85xx headset board consumes less than 0,1 mA measured at the battery
The BQ25015 is also used to charge the Li-ion battery. Charging occurs when both the battery and
the USB cable are connected. The CC85xx headset board can stream audio while the battery is
being charged. The power led D3 (see Appendix B) is lit when
•
the USB cable is connected while the battery is not.
•
the battery is charging (the LED is turned off when charging is complete).
The charge current in the BQ25015 is set to 100 mA. The charging time for the battery is
approximately 5.5h (CC85xx in power down while charging).
6.3 CC2590 Range Extender
As can be seen from Figure 2, the CC85xx Headset board has the CC2590 [9] mounted on the
board. This is a 2.4 GHz range extender which works seamlessly together with all the CC85xx
family members. The CC2590 provides a PA for increased output power (up to +11 dBm) and an
LNA for improved receiver sensitivity (typically 4 dB with the CC85xx). The CC2590 is not
mandatory in a design with the CC85xx but can be utilized where increased range is needed.