
10
AT89C5131A-L
4338F–USB–08/07
Table 12. Power Signal Description
Signal
Name
Type
Description
Alternate
Function
AVSS
GND
Alternate Ground
AVSS is used to supply the on-chip PLL and the USB PAD.
-
AVDD
PWR
Alternate Supply Voltage
AVDD is used to supply the on-chip PLL and the USB PAD.
-
VSS
GND
Digital Ground
VSS is used to supply the buffer ring and the digital core.
-
VDD
PWR
Digital Supply Voltage
VDD is used to supply the buffer ring on all versions of the device.
It is also used to power the on-chip voltage regulator of the Standard
versions or the digital core of the Low Power versions.
-
VREF
O
USB pull-up Controlled Output
VREF is used to control the USB D+ 1.5 k pull up.
The Vref output is in high impedance when the bit DETACH is set in the
USBCON register.
-