UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 118

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

4.3 CLOCK GENERATOR OPERATION
4.3.1 Clock Oscillator
(1) When using crystal/ceramic oscillation
(2) When using external clock
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Cautions 1. When using a crystal/ceramic oscillation, the EXTC bit of the Oscillation stabilization time specifica-
The clock oscillator starts oscillating when the RESET signal is input, and stops oscillation when the STOP mode is set by
the standby control register (STBC). Oscillation is resumed when the STOP mode is released.
The clock oscillator supplies the clock input from the X1 pin to the internal circuitry when the RESET signal is input.
The oscillation circuit operates as follows when the EXTC bit of the oscillation stabilization time specification register (OSTS)
is set to 1.
• The clock oscillator is set in the external clock input mode.
• The clock oscillator supplies the clock input to the X2 pin to the internal circuitry.
• The necessary circuit stops operating during the crystal/ceramic oscillation of the clock oscillator, to reduce the power
• The STOP mode can be used even when the external clock is input.
dissipation.
2. If the STOP mode is used with external clock input, the EXTC bit of the OSTS must be set (1) before
3. When setting the EXTC bit of OSTS to 1, be sure to input a clock in phase reverse to that of the clock
tion register (OSTS) must be cleared (0). If the EXTC bit is set (1), oscillation will stop.
setting the STOP mode. If the STOP mode is used when the EXTC bit is in the cleared (0) state, not
only will the clock generator consumption current not be reduced, but the PD784026 may also be
damaged or suffer reduced reliability.
input to the X1 pin, to the X2 pin.
CHAPTER 4 CLOCK GENERATOR