SM1350AAQM

SEIKO NPC CORPORATION - 7

FUNCTIONAL DESCRIPTION

Chattering Prevention

STN, STOP chattering prevention function

(a) Oscillator stopping （Standby Mode）

The oscillator starts when STN goes from HIGH to LOW in standby mode. Input data is received and melody data

output starts 81.9ms after the oscillator start if STN is LOW. SM1350 dose not operate even if the signal is input to

STOP in standby mode.

81.9ms

81.9ms

61.0Hz

STN

OSC

Input Reception

Melody Output

(SP pin)

Figure 1. STN,STOP chattering prevention timing (oscillator stopping）

(b) Oscillator running

Input data is considered valid 81.9ms after STN and STOP have last changed state. Input data is considered invalid

for intervals less than 65.5ms.

81.9ms

65.5ms

61.0Hz

STN or

STOP

Input Reception

Figure 2. STN,STOP chattering prevention timing (oscillator running）