MC9S12E256 Datasheet, PDF (561/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

A.1.3 Pins
There are four groups of functional pins.
Appendix A Electrical Characteristics
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.
MC9S12E256 Data Sheet, Rev. 1.08
Freescale Semiconductor
561