WF5028 series
FUNCTIONAL DESCRIPTION
Standby Function
When INHN goes LOW, the Q output becomes high impedance.
INHN
HIGH (or open)
LOW
Q
Oscillator
Normal operation
Stopped
Frequency output
High impedance
Power-saving Pull-up Resistor
The INHN pin pull-up resistance R
or R
changes in response to the input level (HIGH or LOW). When
UP1
UP2
INHN is tied LOW level, the pull-up resistance is large (R ), reducing the current consumed by the resis-
UP1
tance. When INHN is left open circuit, the pull-up resistance is small (R ), which increases the input suscep-
UP2
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 WF5028 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.
SEIKO NPC CORPORATION —9
NPC [ NIPPON PRECISION CIRCUITS INC ]
