SH7149 datasheet(116/1022 Pages) RENESAS

116 / 1022 page

Section 4 Clock Pulse Generator (CPG)

Rev. 3.00 May 17, 2007 Page 72 of 974

REJ09B0229-0300

4.7

Function for Detecting Oscillator Stop

This CPG detects a stop in the clock input if any system abnormality halts the clock supply.

When no change has been detected in the EXTAL input for a certain period, the OSCSTOP bit in

OSCCR is set to 1 and this state is retained until a power-on reset is input through the

RES pin or

software standby mode is canceled. If the OSCERS bit is set to 1 at this time, an oscillation stop

detection flag signal is output through the

WDTOVF pin. In addition, the high-current ports (pins

to which the TIOC3B, TIOC3D, and TIOC4A to TIOC4D signals in the MTU2 and the TIOC3BS,

TIOC3DS, and TIOC4AS to TIOC4DS signals in the MTU2S are assigned) can be placed in high-

impedance state regardless of the PFC setting. For details, refer to appendix A, Pin States.

Even in software standby mode, these pins can be placed in high-impedance state. For details,

refer to appendix A, Pin States. These pins enter the normal state after software standby mode is

canceled. Under an abnormal condition where oscillation stops while the LSI is not in software

standby mode, LSI operations other than the oscillation stop detection function become

unpredictable. In this case, even after oscillation is restarted, LSI operations including the above

high-current pins become unpredictable.

Even while no change is detected in the EXTAL input, the PLL circuit in this LSI continues

oscillating at a frequency range from 100 kHz to 10 MHz (depending on the temperature and

operating voltage).

SH7149 Datasheet(PDF) 116 Page - Renesas Technology Corp