USB 2.0 Hi-Speed 3-Port Hub Controller Optimized for Portable Applications
Datasheet
Chapter 4 Power Connections
4.1
Integrated Power Regulators
The integrated 3.3V and 1.2V power regulators provide flexibility to the system in providing power the
device. Several different configurations are allowed in order to align the power structure to supplies
available in the system.
The regulators are controlled by RESET_N. When RESET_N is brought high, the 3.3V regulator will
turn on. When RESET_N is brought low the 3.3V regulator will turn off.
4.1.1
3.3V Regulator
The device has an integrated regulator to convert from VBAT to 3.3V.
4.1.2
1.2V Regulator
The device has an integrated regulator to convert from a variable voltage input on VDDCOREREG to
1.2V. The 1.2V regulator is tolerant to the presence of low voltage (~0V) on the VDDCOREREG pin
in order to support system power solutions where a supply is not always present in low power states.
The 1.2V regulator supports an input voltage range consistent with a 1.8V input in order to reduce
power consumption in systems which provide multiple power supply levels. In addition, the 1.2V
regulator supports an input voltage up to 3.3V for systems which provide only a single power supply.
The device will support operation where the 3.3V regulator output can drive the 1.2V regulator input
such that VBAT is the only required supply.
4.2
Power Configurations
The device supports operation with no back current when power is connected in each of the following
configurations. Power connection diagrams for these configurations are included in
4.2.1
4.2.1.1
Single Supply Configurations
VBAT Only
VBAT must be tied to the VBAT system supply. VDD33 and VDDCOREREG must be tied together on
the board. In this configuration the 3.3V and 1.2V regulators will be active.
4.2.1.2
3.3V Only
VBAT must be tied to the 3.3V system supply. VDD33 and VDDCOREREG must be tied together on
the board. In this configuration the 3.3V regulator will operate in dropout mode and the 1.2V regulator
will be active.
4.2.2
4.2.2.1
Dual Supply Configurations
VBAT + 1.8V
VBAT must be tied to the VBAT system supply. VDDCOREREG must be tied to the 1.8V system
supply. In this configuration, the 3.3V regulator and the 1.2V regulator will be active.
SMSC USB3813
17
Revision 1.0 (06-17-13)
DATASHEET
SMSC [ SMSC CORPORATION ]
