5027 series
FUNCTIONAL DESCRIPTION
Standby Function
When INHN goes LOW, the Q output becomes high impedance.
INHN
HIGH (or open)
LOW
Q
Frequency output
High impedance
Oscillator
Normal operation
Stopped
Power-saving Pull-up Resistor
The INHN pin pull-up resistance R
UP1
or R
UP2
changes in response to the input level (HIGH or LOW). When
INHN is tied LOW level, the pull-up resistance is large (R
UP1
), reducing the current consumed by the resis-
tance. When INHN is left open circuit, the pull-up resistance is small (R
UP2
), 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 5027 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 output
at oscillator start-up when power is applied or when INHN is switched.
SEIKO NPC CORPORATION —13
SEIKO [ SEIKO EPSON CORPORATION ]
