USB3329C-GL-TR Datasheet, PDF (37/79 Pages) Microchip Technology – Industry’s Smallest Hi-Speed USB Transceiver with 1.8V ULPI Interface

Industry’s Smallest Hi-Speed USB Transceiver with 1.8V ULPI Interface
Datasheet
RESETB
X
0
1
Table 5.8 USB Audio Switch Enable
VDD18
0
1
1
DP SWITCH ENABLE
1
1
SpkLeftEn
DM SWITCH ENABLE
1
1
SpkRightEn or MicEn
Note: SpkLeftEn, SpkRightEn, and MicEn are enabled in the Carkit Control register.
In addition to USB Audio support the switches can also be used to multiplexed a second FS USB PHY
to the USB connector. The signal quality will be degraded slightly due to the “on” resistance of the
switches. The USB332x single-ended receivers described in Section 5.2.1 are disabled when either
USB Audio switch is enabled.
The USB332x does not provide the DC bias for the audio signals. The SPK_R and SPK_L pins should
be biased to 1.65V when audio signals are routed through the USB332x. This DC bias is necessary
to prevent the audio signal from swinging below ground and being clipped by ESD Diodes.
When the system is not using the USB Audio switches, the SPK_R and SPK_L pins should not be
connected.
SMSC USB332x
37
DATASHEET
Revision 1.1 (11-20-12)