Datasheet

Appendix A Electrical Characteristics
MC9S12E256 Data Sheet, Rev. 1.10
Freescale Semiconductor 573
A.1.3 Pins
There are four groups of functional pins.
A.1.3.1 3.3V/5V I/O Pins
Those I/O pins have a nominal level of 3.3V or 5V depending on the application operating point. This
group of pins is comprised of all port I/O pins, the analog inputs, BKGD pin and the RESET inputs.The
internal structure of all those pins is identical, however some of the functionality may be disabled.
A.1.3.2 Analog Reference
This group of pins is comprised of the VRH and VRL pins.
A.1.3.3 Oscillator
The pins XFC, EXTAL, XTAL dedicated to the oscillator have a nominal 2.5V level. They are supplied by
VDDPLL.
A.1.3.4 TEST
This pin is used for production testing only.
A.1.4 Current Injection
Power supply must maintain regulation within operating V
DD5
or V
DD
range during instantaneous and
operating maximum current conditions. If positive injection current (V
in
>V
DD5
) is greater than I
DD5
, the
injection current may flow out of V
DD5
and could result in external power supply going out of regulation.
Insure external V
DD5
load will shunt current greater than maximum injection current. This will be the
greatest risk when the MCU is not consuming power; e.g. if no system clock is present, or if clock rate is
very low which would reduce overall power consumption.