Motorola MC9S12DT128B manual A.1.3 Pins, A.1.4 Current Injection, Vsspll, A.1.3.1 5V I/O pins

MC9S12DT128B Device User Guide — V01.07

NOTE: In the following context VDD5 is used for either VDDA, VDDR and VDDX; VSS5 is used for either VSSA, VSSR and VSSX unless otherwise noted.

IDD5 denotes the sum of the currents flowing into the VDDA, VDDX and VDDR pins.

VDD is used for VDD1, VDD2 and VDDPLL, VSS is used for VSS1, VSS2 and

VSSPLL.

IDD is used for the sum of the currents flowing into VDD1 and VDD2.

A.1.3 Pins

There are four groups of functional pins.

A.1.3.1 5V I/O pins

Those I/O pins have a nominal level of 5V. This class 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. E.g. for the analog inputs the output drivers, pull-up and pull-down resistors are disabled permanently.

A.1.3.2 Analog Reference

This class is made up by the two 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.1.3.5 VREGEN

This pin is used to enable the on chip voltage regulator.

A.1.4 Current Injection

Power supply must maintain regulation within operating VDD5 or VDD range during instantaneous and operating maximum current conditions. If positive injection current (Vin > VDD5) is greater than IDD5, the injection current may flow out of VDD5 and could result in external power supply going out of regulation. Insure external VDD5 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.

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