MC68HC912DG128 Datasheet, PDF (40/452 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Pinout and Signal Descriptions
3.3 Power Supply Pins
Power and ground pins are described below and summarized in Table
3-1.
3.3.1 Internal Power (V_DD) and Ground (V_SS)
Power is supplied to the MCU through V_DD and V_SS. 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. Bypass requirements
depend on how heavily the MCU pins are loaded.
3.3.2 External Power (V_DDX) and Ground (V_SSX)
External power and ground for I/O drivers. 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. Bypass requirements
depend on how heavily the MCU pins are loaded.
3.3.3 V_DDA, V_SSA
Provides operating voltage and ground for the analog-to-digital
converter. This allows the supply voltage to the ATD to be bypassed
independently. Connecting V_DDA to V_DD if the ATD modules are not
used will not result in an increase of power consumption.
3.3.4 Analog to Digital Reference Voltages (V_RH, V_RL)
V_RH0, V_RL0: reference voltage high and low for ATD converter 0.
V_RH1, V_RL1: reference voltage high and low for ATD converter 1.
If the ATD modules are not used, leaving V_RH connected to V_DD will not
result in an increase of power consumption.
Technical Data
40
MC68HC912DG128 — Rev 3.0
Pinout and Signal Descriptions
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