MC9S12DT256_06 Datasheet, PDF (67/132 Pages) Freescale Semiconductor, Inc – Device User Guide V03.07

MC9S12DT256 Device User Guide — V03.07
2.4.3 VDD1, VDD2, VSS1, VSS2 — Core Power Pins
Power is supplied to the MCU through VDD and VSS. Because fast signal transitions place high,
short-duration current demands on the power supply, use bypass capacitors with high-frequency
characteristics and place them as close to the MCU as possible. This 2.5V supply is derived from the
internal voltage regulator. There is no static load on those pins allowed. The internal voltage regulator is
turned off, if VREGEN is tied to ground.
NOTE: No load allowed except for bypass capacitors.
2.4.4 VDDA, VSSA — Power Supply Pins for ATD and VREG
VDDA, VSSA are the power supply and ground input pins for the voltage regulator and the analog to
digital converter. It also provides the reference for the internal voltage regulator. This allows the supply
voltage to the ATD and the reference voltage to be bypassed independently.
2.4.5 VRH, VRL — ATD Reference Voltage Input Pins
VRH and VRL are the reference voltage input pins for the analog to digital converter.
2.4.6 VDDPLL, VSSPLL — Power Supply Pins for PLL
Provides operating voltage and ground for the Oscillator and the Phased-Locked Loop. This allows the
supply voltage to the Oscillator and PLL to be bypassed independently.This 2.5V voltage is generated by
the internal voltage regulator.
NOTE: No load allowed except for bypass capacitors.
Table 2-2 MC9S12DP256 Power and Ground Connection Summary
Pin Number
Mnemonic
112-pin QFP
Nominal
Voltage
Description
V_{DD1, 2}
V_{SS1, 2}
V_DDR
V_SSR
V_DDX
V_SSX
V_DDA
V_SSA
13, 65
14, 66
41
40
107
106
83
86
2.5 V
0V
5.0 V
0V
5.0 V
0V
5.0 V
0V
Internal power and ground generated by internal regulator
External power and ground, supply to pin drivers and internal
voltage regulator.
External power and ground, supply to pin drivers.
Operating voltage and ground for the analog-to-digital
converters and the reference for the internal voltage regulator,
allows the supply voltage to the A/D to be bypassed
independently.
V_RL
85
0V
Reference voltages for the analog-to-digital converter.
V_RH
84
5.0 V
67