MC9S12A256B ETC, MC9S12A256B Datasheet - Page 88

• Manufacturer Part Number: MC9S12A256B
• Description: device made up of standard HCS12 blocks and the HCS12 processor core
• Manufacturer: ETC

MC9S12DP256B Device User Guide — V02.14
The VDDX, VSSX, VDDR and VSSR pairs supply the I/O pins, VDDR supplies also the internal voltage
regulator.
VDD1, VSS1, VDD2 and VSS2 are the supply pins for the digital logic, VDDPLL, VSSPLL supply the
oscillator and the PLL.
VSS1 and VSS2 are internally connected by metal.
VDDA, VDDX, VDDR as well as VSSA, VSSX, VSSR are connected by anti-parallel diodes for ESD
protection.
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 and the RESET pins.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 group is made up by 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.1.3.5 VREGEN
This pin is used to enable the on chip voltage regulator.
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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.
Freescale Semiconductor, Inc.
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