Datasheet

3
8042ES–AVR–09/2013
ATmega16HVB/32HVB
1.2 Pin descriptions
1.2.1 VFET
High voltage supply pin. This pin is used as supply for the internal voltage regulator, described in
”Voltage regulator” on page 129.
1.2.2 VCLMP10
Internal 10V clamping of VFET voltage for external decoupling.
1.2.3 VCC
Digital supply voltage. Normally connected to VREG.
1.2.4 VREG
Output from the internal voltage regulator. Used for external decoupling to ensure stable regula-
tor operation. For details, see ”Voltage regulator” on page 129.
1.2.5 VREF
Internal voltage reference for external decoupling. For details, see ”Voltage reference and tem-
perature sensor” on page 122.
1.2.6 VREFGND
Ground for decoupling of internal voltage reference. For details, see ”Voltage reference and
temperature sensor” on page 122. Do not connect to GND or SGND on PCB.
1.2.7 GND
Ground.
1.2.8 Port A (PA3..PA0)
Port A serves as a low-voltage 4-bit bi-directional I/O port with internal pull-up resistors (selected
for each bit). As inputs, Port A pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port A pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port A also serves the functions of various special features of the Atmel ATmega16HVB/32HVB
as listed in ”Alternate functions of Port A” on page 74.
1.2.9 Port B (PB7..PB0)
Port B is a low-voltage 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port B also serves the functions of various special features of the ATmega16HVB/32HVB as
listed in ”Alternate functions of Port B” on page 75.
1.2.10 Port C (PC5)
Port C (PC5) is a high voltage Open Drain output port.