Highly Integrated Full Featured Hi-Speed USB 2.0 ULPI Transceiver
Datasheet
The USB3320 includes an integrated 3.3V Low Drop Out (LDO) regulator that may optionally be used
to generate 3.3V from power applied at the VBAT pin. The voltage on the VBAT pin can range from
3.1 to 5.5V. The regulator dropout voltage is less than 100mV which allows the transceiver to continue
USB signaling when the voltage on VBAT drops to 3.1V. The USB transceiver will continue to operate
at lower voltages, although some parameters may be outside the limits of the USB specifications. If
the user would like to provide a 3.3V supply to the USB3320, the VBAT and VDD33 pins should be
connected together as described in Section 5.5.1.
The USB3320 also includes integrated pull-up resistors that can be used for detecting the attachment
of a USB Charger. By sensing the attachment to a USB Charger, a product using the USB3320 can
charge its battery at more than the 500mA allowed when charging from a USB Host. Please see SMSC
Application Note AN 19.7 - Battery Charging Using SMSC USB Transceivers for more information on
battery charging.
In USB UART mode, the USB3320 DP and DM pins are redefined to enable pass-through of
asynchronous serial data. The USB3320 can only enter UART mode when the user programs the part
into this mode, as described in Section 6.5.1.
In USB audio mode, a switch connects the DP pin to the SPK_R pin, and another switch connects he
DM pin to the SPK_L pin. These switches are shown in the lower left-hand corner of Figure 5.1. The
USB3320 can be configured to enter USB audio mode as described in Section 6.5.2. In addition, these
switches are on when the RESETB pin of the USB3320 is asserted. The USB audio mode enables
audio signalling from a single USB port of connection, and the switches may also be used to connect
Full Speed USB from another transceiver onto the USB cable.
SMSC USB3320
9
Revision 1.0 (07-14-09)
DATASHEET
SMSC [ SMSC CORPORATION ]
