WF5027 datasheet(13/21 Pages) NPC

13 / 21 page

WF5027 series

SEIKO NPC CORPORATION —13

FUNCTIONAL DESCRIPTION

Standby Function

When INHN goes LOW, the Q output becomes high impedance.

Power-saving Pull-up Resistor

The INHN pin pull-up resistance RUP1 or RUP2 changes in response to the input level (HIGH or LOW). When

INHN is tied LOW level, the pull-up resistance is large (RUP1), reducing the current consumed by the resis-

tance. When INHN is left open circuit, the pull-up resistance is small (RUP2), which increases the input suscep-

tibility to external noise. However, the pull-up resistance ties the INHN pin HIGH level to prevent external

noise from unexpectedly stopping the output.

Oscillation Detector Function

The WF5027 series also feature an oscillation detector circuit. This circuit functions to disable the outputs until

the oscillator circuit starts and oscillation becomes stable. This alleviates the danger of abnormal oscillator out-

put at oscillator start-up when power is applied or when INHN is switched.

INHN

Oscillator

HIGH (or open)

Frequency output

Normal operation

LOW

High impedance

Stopped

WF5027 Datasheet(PDF) 13 Page - Nippon Precision Circuits Inc