SX8124ISTRT SEMTECH [Semtech Corporation], SX8124ISTRT Datasheet - Page 12

• Manufacturer Part Number: SX8124ISTRT
• Description: 24 hours timer synchronized on 50/60Hz mains
• Manufacturer: SEMTECH [Semtech Corporation]

ACS - Revision 2.4
© Semtech Corp.
8
8.1
8.2
ADVANCED COMMUNICATIONS & SENSING
50 Hz
signal
Timer synchronization on a 50Hz or 60Hz external phase
To avoid timing drifts over the time, the SX8124 can be synchronised on a signal from the mains.
The SX8124 permanently checks the duration between two consecutive edges on the PHASE pin.
External phase available for synchronization
Please note that for correct phase detection the edges on the PHASE pin must be sharp . A sinus or triangular
wave is not recommended.
No phase available for synchronization
If there is no clean 50Hz or 60Hz signal on PHASE pin, the system timing switch on the internal RC oscillator. In
this case the timer will be 10% precise. The LED output is sending 2Hz burst to indicate that the timer is not
synchronized and counting based on the internal base time.
The maximum frequency on PHASE pin should not exceed 20kHz. If the signal on this pin has a frequency
potentially higher than 20kHz it must be low pass filtered with a capacitor.
No signal
or noise
PHASE
PHASE
October 2010
Figure 10. Timer not synchronized on an external phase
Figure 9. Example: timer synchronized on a 50Hz phase
Oscillator
detect
detect
Oscillator
60 Hz
50 Hz
RC
detect
detect
60 Hz
50 Hz
RC
Page 12
24 hours timer synchronized on 50/60Hz mains
TIMER
TIMER
24H
24H
Output
control
Burst gen
Output
control
Burst gen
www.semtech.com/products/
LED
LED
If OUT and NOUT are on :
If OUT and NOUT are off :
SX8124
DATASHEET