CONSONANCE

reset pulse, the pulse will continue for at least another 140ms. On power down , once VCC falls below reset

threshold, RESET stays valid

and is guaranteed in the correct logic state

until VCC drops below 1.15V

for the whole temperature range. Please refer to Figure 5.

CN705/706 series provide

active low

signal；CN707/708

series provide both active high and

active low RESET signals；CN813 series provide active high RESET signal.

Watchdog Timer

CN705/706/813 series have an independent watchdog timer that can monitor uP’s

activity. If uP does not

toggle the watchdog input (WDI) within 1.6s and WDI is not three-stated, WDO goes low.

As

long as

RESET is asserted, or WDI is three-stated, or WDI is left floating, the watchdog timer stays cleared and

will not count, in this case WDO is in high state. When VCC stays below reset threshold, WDO goes low

whether or not the watchdog timer has timed out yet. Please refer to figure 4.

Manual Reset

Manual reset input allows reset signal to be triggered by push button or switch. The push button or switch

is effectively debounced by 140ms minimum reset pulse width.

is TTL/CMOS logic compatible.

can be used to force a watchdog timeout to generate a reset pulse in CN705/706/813 series by connecting

WDO to

Please refer to Figure 5.

Power fail Comparator

The power fail comparator can be used for various purpose because its output and noninverting input are

not internally connected. The inverting input is internally connected to a 1.22V reference voltage.

WDI

WDO

RESET

RESET

Note 1: RESET (RESET) is triggered by MR

Note 2: RESET is for CN813X and CN706P only

Figure 4 Watchdog Timing

Rev.1

9