M16C/62 Group DATASHEET

Clock Generating CircuitMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERClock Generating CircuitThe clock generating circuit contains two oscillator circuits that supply the operating clock sources to theCPU and internal peripheral units.Table 1.13.1. Main clock and sub-clock generating circuitsMain clock generating circuit Sub-clock generating circuitUse of clock • CPU’s operating clock source • CPU’s operating clock source• Internal peripheral units’ • Timer A/B’s count clockoperating clock source sourceUsable oscillator Ceramic or crystal oscillator Crystal oscillatorPins to connect oscillator XIN, XOUT XCIN, XCOUTOscillation stop/restart function Available AvailableOscillator status immediately after reset Oscillating StoppedOtherExternally derived clock can be inputExample of oscillator circuitFigure 1.13.1 shows some examples of the main clock circuit, one using an oscillator connected to thecircuit, and the other one using an externally derived clock for input. Figure 1.13.2 shows some examplesof sub-clock circuits, one using an oscillator connected to the circuit, and the other one using an externallyderived clock for input. Circuit constants in Figures 1.13.1 and 1.13.2 vary with each oscillator used. Usethe values recommended by the manufacturer of your oscillator.Microcomputer(Built-in feedback resistor)Microcomputer(Built-in feedback resistor)XINXOUT(Note)RdXINXOUTOpenExternally derived clockCINCOUTVccVssNote: Insert a damping resistor if required. The resistance will vary depending on the oscillator and the oscillation drivecapacity setting. Use the value recommended by the maker of the oscillator.When the oscillation drive capacity is set to low, check that oscillation is stable. Also, if the oscillator manufacturer'sdata sheet specifies that a feedback resistor be added external to the chip, insert a feedback resistor between XINand XOUT following the instruction.Figure 1.13.1. Examples of main clockMicrocomputer(Built-in feedback resistor)Microcomputer(Built-in feedback resistor)XCINXCOUT(Note)RCdXCINXCOUTOpenExternally derived clockCCINCCOUTVccVssNote: Insert a damping resistor if required. The resistance will vary depending on the oscillator and the oscillation drivecapacity setting. Use the value recommended by the maker of the oscillator.When the oscillation drive capacity is set to low, check that oscillation is stable. Also, if the oscillator manufacturer'sdata sheet specifies that a feedback resistor be added external to the chip, insert a feedback resistor between XCINand XCOUT following the instruction.Figure 1.13.2. Examples of sub-clock40