TDA7421 Datasheet, PDF (17/38 Pages) STMicroelectronics – AM/FM TUNER FOR CAR RADIO AND Hi-Fi APPLICATIONS

TDA7421
ttim = (IFRC + 1) / fosc
tcnt = (CF + 1697) / fIF
tcnt = (CF + 44) / fIF
FM mode
AM mode
Counter result succeeded:
ttim > tcnt - terr and
ttim > tcnt + terr
Counter result failed:
ttim< tcnt + terr or
ttim > tcnt - terr
where:
ttim = IF time cycle time
tcnt = IF counter cycle time
terr = discrimination window (controlled by the EW
registers)
succeeded
failed ^{tcnt -tERR}
t_cnt +t_ERR
failed
t_tim
D96AU551
The precision of the measurements is adjustable
Phase Comparator
by controlling the discrimination window. This is
adjustable by programming the control registers
EW0...EW2.
The measurement time per cycle is adjustable by
setting the register IFS0 - IFS2.
The center frequency of the discrimination win-
dow is adjustable by the control register "CF0" to
"CF4". The available values are reported in dat-
abyte specification
I²C BUS INTERFACE
General Description
The TDA7421 supports the I²C bus protocol. This
protocol defines the devices sending data into the
bus as transmitter and the receiving device as the
receiver.
The device that controls the transfer is a master
and the device being controlled is the slave. The
master will always initiates data transfer and pro-
vide the clock to transmit or receive operations.
Data Transition
Data transition on the SDA line must only occur
when the clock SCL is low. SDA transitions while
SCL is high will be interpreted as START or
STOP condition.
Start Condition
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