
Pin Description
Pin Name
I/O
Description
PA0~PA7
I/O
Bidirectional 8-bit input/output port. Each bit can be configured as a wake-up input by a
configuration option. Software instructions determine if the pin is a CMOS output or a Schmitt
trigger input. Pull-high resistor can be connected to the pins via configuration options - nibble
option.
PC7/SCK
I/O
Can be software optioned as a bidirectional input/output or serial interface clock signal.
PC6/SCS
I/O
Can be software optioned as a bidirectional input/output or serial interface slave select signal.
PC5/SDI
I/O or
O
Can be software optioned as a bidirectional input/output or serial data input.
PC4/SDO
I/O or
O
Can be software optioned as a bidirectional input/output or serial data output.
PC3
I/O
Bidirectional I/O lines. Software instructions determine if the pin is a CMOS output or a Schmitt
trigger input. Pull-high resistor can be connected to the pins via configuration options.
PC2/TMR1,
PC1/TMR0
I/O
Software instructions determine if the pin is a CMOS output or a Schmitt trigger input. Pull-high
resistor can be connected to the pins via configuration options.TMR0, TMR1 are pin shared with
PC1, PC2 respectively.
PC0/BZ
I/O or
O
Can be software optioned as a bidirectional input/output or as a PFD output.
OSCI
OSCO
I
O
OSCI, OSCO are connected to an 6MHz or 12MHz crystal/resonator (determined by software
instructions) for the internal system clock
RESET
I
Schmitt trigger reset input, active low
DVDD1
Positive digital power supply
USBDN
I/O
USBD- line. The USB function is controlled by a software control register
USBDP
I/O
USBD+ line. The USB function is controlled by a software control register
V33O
O
3.3V regulator output
DVSS1
Negative digital power supply, ground
Absolute Maximum Ratings
Supply Voltage...........................V
SS
0.3V to V
SS
+6.0V
Storage Temperature............................ 50 C to 125 C
Input Voltage..............................V
SS
0.3V to V
DD
+0.3V
Operating Temperature........................... 40 C to 85 C
I
OL
Total ..............................................................150mA
I
OH
Total............................................................ 100mA
Total Power Dissipation.....................................500mW
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maximum Ratings may
cause substantial damage to the device. Functional operation of this device at other conditions beyond those
listed in the specification is not implied and prolonged exposure to extreme conditions may affect device
reliability.
HT82A851R
Rev. 1.20
3
June 15, 2007