Page 11

ADVANCED COMMUNICATIONS & SENSING

DATASHEET

SX8124

24 hours timer synchronized on 50/60Hz mains

ACS - Revision 2.4

October 2010

© Semtech Corp.

7

Setting duration

The measurement of DURATION pin voltage is ratiometric to VDD. The 24h duty cycle on OUT and NOUT pins

is equal to the relative voltage on pin DURATION versus the voltage on pin VDD. For example if DURATION is

1/3 of VDD, OUT will be high for 8 hours and down for 16 hours.

The voltage resolution on the DURATION pin is 256, so the OUT and NOUT pin can toggle at each step of 24H

/ 256 = 5.625 minutes.

Steps 0 to 2 on the DURATION pin are reserved for detection of a Reset command with the pin set to ground.

The timer can not be set to toggle OUT and NOUT during the 15 first minutes after the start of the 24H cycle.

See “Reset with the DURATION pin” on page 14 .

While the duration is set to ‘0’, the LED pin is not active and set to VSS.

Figure 7. 256 steps resolution on DURATION pin

Figure 8. 256 steps on the 24H timer cycle

DURATION

SX8124

VSS

VDD

VDD

256

0

128

VSS

OUT

24h cycle

Next 24h cycle

NOUT

start timer

toggle at set duration

(re)start

Step 0

Step 128

Step 256