SCT1555 Datasheet, PDF (1/10 Pages) Zetex Semiconductors – PRECISION SINGLE CELL TIMER

PRECISION SINGLE CELL TIMER
ZSCT1555
ISSUE 2 - MAY 1998
DEVICE DESCRIPTION
These devices are precision timing circuits for
generation of accurate time delays or
oscillation. Advanced circuit design means that
these devices can operate from a single battery
cell with the minimum of quiescent current.
In monostable mode time delays are
controlled by a single resistor and capacitor
network. In astable mode the frequency and
duty cycle can be accurately and
independently controlled with two external
resistors and one capacitor.
The threshold and trigger levels are normally
set as a proportion of V_CC by internal resistors.
These levels can be programmed by the use
of the control input pin.
When the trigger input reduces to a value
below the trigger level, the flip-flop is set and
the output goes high. With the trigger input
above the trigger level and the threshold input
above the threshold level, the flip-flop is reset
SCHEMATIC DIAGRAM
8
VCC
and the output goes low. The reset pin has
priority over all the other inputs and is used
to start new timing cycles. A low on the reset
input causes the flip-flop to reset forcing the
output low. Whenever the output is forced
low then the internal discharge transistor is
turned on.
FEATURES
• ^{0.9V supply operating voltage guaranteed}
• ^{Pin connections comparable with 555}
series timers
• ^{Very low quiescent current 74 µA}
• ^{SO8 and DIL8 packages}
• ^{Operating temperature range}
compatible with battery technologies
APPLICATIONS
• ^{Portable and battery powered}
equipment
• ^{Low voltage and low power systems}
CONTROL
5
6
THRESH
2
TRIGGER
7
DISCHARGE
4
RESET
4-311
3
OUTPUT
1
GND