r5f21368sdfp Renesas Electronics Corporation., r5f21368sdfp Datasheet - Page 144

• Manufacturer Part Number: r5f21368sdfp
• Description: Renesas Mcu R8c Family / R8c/3xt-a Series
• Manufacturer: Renesas Electronics Corporation.

Under development
R8C/36T-A Group
R01UH0240EJ0001 Rev.0.01
Apr 28, 2011
10.3.1
10.3.2
10.3.3
10.3.4
The CPU clock is obtained by dividing the XIN clock by 1 (no division), 2, 4, 8, or 16. When the CM14 bit in
the CM1 register is 0 (low-speed on-chip oscillator on) or the FRA00 bit in the FRA0register is 1 (high-speed
on-chip oscillator on), fOCO can be used for timer RJ.
When the FRA00 bit is 1, fHOCO can be used for timer RC.
When the CM14 bit is 0 (low-speed on-chip oscillator on), fLOCO can be used for the voltage detection circuit.
The CPU clock is obtained by dividing the XCIN clock by 1 (no division), 2, 4, 8, or 16.
In this mode, low-power operation can be enabled by stopping the XIN clock and the high-speed on-chip
oscillator and setting the FMR27 bit in the FMR2 register to 1 (low-current-consumption read mode enabled).
When the FRA00 bit is 1, fHOCO can be used for timer RC.
When the CM14 bit is 0 (low-speed on-chip oscillator on), fLOCO can be used for the voltage detection circuit.
Furthermore, if the MCU enters wait mode from this mode, current consumption in wait mode can be reduced
even further by setting the SVD0 bit in the SVDC register to 1 (transition to low-power-consumption mode
enabled).
For details on how to reduce power consumption, refer to 10.6 Reducing Power Consumption.
When the FRA00 bit is 1 (high-speed on-chip oscillator on) and bits CM42 to CM40 in the CM4 register are
101b, the high-speed on-chip oscillator clock is used as the on-chip oscillator clock. At this time, the CPU clock
is obtained by dividing the on-chip oscillator clock by 1 (no division), 2, 4, 8, or 16. When the FRA00 bit is 1,
fHOCO can be used for timer RC.
When the CM14 bit is 0 (low-speed on-chip oscillator on), fLOCO can be used for the voltage detection circuit.
When the CM14 bit is 0 (low-speed on-chip oscillator on) and bits CM42 to CM40 are 001b, the low-speed on-
chip oscillator clock is used as the on-chip oscillator clock. At this time, the CPU clock is obtained by dividing
the on-chip oscillator clock by 1 (no division), 2, 4, 8, or 16. Also, the on-chip oscillator clock is used as the
clock source for the peripheral function clocks. When the FRA00 bit is 1, fHOCO can be used for timer RC.
When the CM14 bit is 0 (low-speed on-chip oscillator on), fLOCO can be used for the voltage detection circuit.
In this mode, low-power operation can be enabled by stopping the XIN clock and the high-speed on-chip
oscillator and setting the FMR27 bit to 1 (low-current-consumption read mode enabled). Low-power-
consumption mode can be used when the CPU clock is the low-speed on-chip oscillator divided by 4, 8 or 16.
When the CPU clock is the low-speed on-chip oscillator divided by 1 (no division) or 2, do not use low-power-
consumption mode. Set the FMR27 bit to 1 after setting the division ratio for the CPU clock.
Furthermore, if the MCU enters wait mode from this mode, current consumption in wait mode can be reduced
even further by setting the SVD0 bit to 1 (transition to low-power-consumption mode enabled).
For details on how to reduce power consumption, refer to 10.6 Reducing Power Consumption.
High-Speed Clock Mode
Low-Speed Clock Mode
High-Speed On-Chip Oscillator Mode
Low-Speed On-Chip Oscillator Mode
Preliminary document
Specifications in this document are tentative and subject to change.
10. Power Control
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