HA16129AFPJ

Rev.1.00 Jun 15, 2005 page 6 of 22

OUTE Function

When a microprocessor is in the runaway state, its outputs are undefined, and thus it is possible that the outputs may be

driven by incorrect signals. This function is used to mask such incorrect microprocessor outputs. When the WDT

function recognizes normal operation (when the

RES output is high), the OUTE output will be held high. When the

WDT function recognizes an abnormal state and an auto-reset pulse is output from the

RES pin, the OUTE output will

be held low. Thus microprocessor outputs during microprocessor runaway can be masked by taking the AND of those

outputs and this signal using external AND gates.

below VthLcr.

There are limitation that apply when the OUTE function is used. Refer to the calculation formulas item for details.

RES Function

This period is the length of the high-level output period of the

RES pulse when the P-RUN signal from the

This period is the length of the low-level output period of the

RES pulse when the P-RUN signal from the

This is the time from the point the P-RUN signal from the microprocessor stops to the point a low level is output

from the

RES pin. During normal microprocessor operation, the potential on the C

(although this value may change with the P-RUN signal input conditions, so it should be verified in the actual

• tr

The time tr is the fixed delay time between the point the

NMI output goes from low to high after the power-supply

voltage comes up to the point

RES goes from low to high. The time tr is the time for the CRES pin potential to fall

from the high voltage (about 1.9 V) to Vthcres.

supply voltage falls to the point

RES goes from high to low. The time t

rise from 0 V to Vthcres.

WDT Function

This function determines whether the microprocessor is operating normally or has entered a runaway state by

monitoring the duty or frequency of the P-RUN signal. When this function recognizes a runaway state, it outputs a

reset pulse from the

RES pin and sets the OUTE pin to low from high. It holds the RES and OUTE pins fixed at high as

long as it recognizes normal microprocessor operation.

In this function, the potential of the Cf capacitor is controlled by the P-RUN signal. This Cf pin potential charges the

microprocessor is operating normally, is determined by the balance between the charge and discharge voltage on the