ST7538Q STMicroelectronics, ST7538Q Datasheet - Page 37

• Manufacturer Part Number: ST7538Q
• Description: IC TXRX FSK POWER LINE 44-TQFP
• Manufacturer: STMicroelectronics
• Type: Transceiverr

Specifications of ST7538Q

• Number Of Drivers/receivers: 1/1
• Voltage - Supply: 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 44-TQFP Exposed Pad, 44-eTQFP, 44-HTQFP, 44-VQFP
• For Use With: 497-5484 - BOARD EVAL ST7538 PWR LINE TXRX
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Protocol: -
• Other names: 497-5525

ST7538Q
6.4
Figure 21. Reset and watchdog timing
Zero crossing detection
The Mains Voltage Zero Crossing can be detected, through a proper connection of ZCIN to
the Mains. ZCIN comparator has a threshold fixed at SGND. ZCOUT is a TTL Output forced
High after a positive zero-crossing transition, and low after a negative one.
Setting the Bit 11 inside the Control Register to “1” the transmission is automatically
synchronized to the mains positive zero-crossing transition. This function is achieved turning
on the PLI when RX/TX is low and delaying the CLR/T first transition until the first zero-
crossing event. The automatic synchronization procedure can work only if the synchronous
interface is programmed. If asynchronous interface is in use the Zero Crossing
synchronization can be achieved managing the ZCOUT line.
Figure 22. Synchronous zero-crossing transmission
RSTO
WD
ZCOUT
CLR/T
ZCIN
RxTx
TxD
T
RSTO
ZC
DEL
T
WD
T
WM
T
WO
Auxiliary analog and digital functions
T
RSTO
D03IN1423
D03IN1410
t
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