R
A3024
Process Application
Oscillator Layout
VSS
VDD
Temperature
sensor
XIN
XOUT
Controller
Solenoid
valve
Fig. 14
Fig. 15
- The formula in Fig. 5 is used by software to continually update
the digital trimming register and so compensate the A3024 for
the ambient temperature.
- The timer is used to measure the duration the valve is on.
- The alarm feature is used to turn the controller power on and
off at the time programmed by software. The A3024 pulls IRQ
active low on an alarm even in standby and thus can control
the power on/off switch for the controller.
External Clock
An external signal generator can be used to drive the divider
chain of the A 3024. Fig. 16a and 16b show how to connect the
signal generator.
Signal Generator
- The user RAM provides the controller with non volatile RAM
for vital parameters. For example :
1) the total on time for the valve to enable software to
compute energy usage and also to identify when service is
XIN
1- 2 V peak to peak
needed
- 3 bytes
- 2 bytes
3) maximum temperature ever encountered together with the
A3024
2) average on time for the valve
XOUT
time and date
4) date of last service and service man’s ID
5) identification code for the controller
- 6 bytes
- 4 bytes
- 1 byte
VSS
Fig. 16a
Crystal Layout
Note : The peak value of the signal provided by the signal
generator should not exceed 2 V on XOUT.
In order to ensure proper oscillator operation we recommend
the following standard practices:
- Keep traces as short as possible.
- Use a guard ring around the crystal.
Fig. 15 shows the recommended layout.
XIN
0 - 5.5 V
100 kW1)
A3024
XOUT
56 kW1)
VSS
1)indicative values
Fig. 16b
Note : The peak value of the signal provided by the signal
generator should not exceed 2 V on XOUT
.
15
EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
