MLX90720 Datasheet, PDF (2/12 Pages) List of Unclassifed Manufacturers – One Button Timer

MLX90720
One Button Timer
General Description
The electronic timer is a self-powered device,
programmable from 0 to 99 minutes, with ringing at
the end of countdown. The timer has an internal
memory which stores the last programmed time.
An auto shut-off and a validation of the countdown
(blinking display) are also provided.
The chip is designed to be used with a 2 backplanes
LCD :
Operation Voltage 3V
Driving condition 1/2 Duty, 1/2 Bias
The timer chip has an output ( RELO ) for driving an
external low power NPN bipolar transistor and a
buzzer driver output.
RELO output
The timer chip has an output ( RELO ) for driving an
external low power NPN bipolar transistor. This NPN
transistor could be used for driving a switching
element (relay). It can be connected directly (base to
RELO) or through a resistor from 100 to 200 ohms.
Buzzer output
The chip has an output driver to drive a magnetic
transducer. The frequency generated at this output is
2048 Hz.
Configurations
4 different configurations are possible and are
defined according to the following table:
Configuration 1
Configuration 2
Configuration 3
Configuration 4
MTST
0
1
0
1
MSEL
0
0
1
1
1: connected to Vdd.
0: connected to Vss.
Configuration 1: Minutes mode (a) : countdown in
minutes and the last minute is displayed in seconds.
Configuration 2: Minutes mode (b): countdown in
minutes and the last minute is not displayed in
seconds.
Configuration 3: Minutes mode (c) : countdown in
minutes with a 0.5 min. step from 10 min to 1 min
and the last minute in seconds.
Configuration 4: Seconds mode.
Options
In each configuration two options are possible: the
restore memory option and the second fast
increment option.
The restore memory option is available in one button
version (OBT: One Button Timer) or two button
version (TBT: Two Button Timer) (see functional
description on following pages). With this option the
last programmed time can be restored.
The chip operates in OBT mode with restore
memory, if pin REC is connected to VDD and
operates in TBT mode, if REC is connected to VSS
and button 2 is bonded. When the restore function is
not used, REC is connected to VSS and button 2 is
not used.
The TBT also has more flexibility in programming
mode, as the time can not only be increased but also
decreased.
The second fast increment option can be chosen to
have two increment speeds in programming mode to
set the desired time. The chip operates in this mode
if pin FST is connected to Vdd.
Modes
The timer has 6 modes of operation:
Wake up mode
Programming mode
Count down mode
Ringing mode
Wait mode
Power down mode
The timer is always in one of these modes.
Functional description
The following paragraph describes the functionality
of the asic in configuration 1, but with different
options.
Basic OBT
The basic One Button Timer has no second button,
no restore memory and no second fast increment
option.
Wake up:
The first press enables the wake up of the chip within
two seconds (debouncing + startup of the oscillator).
The value 00 is displayed (non-blinking) and the chip
enters programming mode.
Programming mode:
The programming of the timer is implemented with
one button. In this mode the display doesn't blink.
MLX90720 One Button Timer
Page 2
Rev 1.0 30/Nov/00