SI4735-D60-GU Silicon Laboratories Inc, SI4735-D60-GU Datasheet - Page 27

• Manufacturer Part Number: SI4735-D60-GU
• Description: RF RX FM AM SW LW 24 SSOP
• Manufacturer: Silicon Laboratories Inc
• Series: -r

Specifications of SI4735-D60-GU

• Mfg Application Notes: SI47xx Prog Guide AppNote
• Frequency: 153kHz ~ 279kHz, 520kHz ~ 1.71MHz, 2.3MHz ~ 26.1MHz, 64MHz ~ 108MHz
• Sensitivity: -
• Data Rate - Maximum: -
• Modulation Or Protocol: AM, FM, SW-LW
• Applications: General Purpose
• Current - Receiving: 18.5mA
• Data Interface: PCB, Surface Mount
• Memory Size: -
• Antenna Connector: PCB, Surface Mount
• Features: RSSI Equipped
• Voltage - Supply: 2 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 24-SSOP (0.154", 3.90mm Width)
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-2140

4.15. De-emphasis
Pre-emphasis and de-emphasis is a technique used by
FM broadcasters to improve the signal-to-noise ratio of
FM receivers by reducing the effects of high-frequency
interference and noise. When the FM signal is
transmitted, a pre-emphasis filter is applied to
accentuate the high audio frequencies. The Si473x
incorporates a de-emphasis filter which attenuates high
frequencies to restore a flat frequency response. Two
time constants are used in various regions. The de-
emphasis time constant is programmable to 50 or 75 µs
and is set by the FM_DEEMPHASIS property.
4.16. RDS/RBDS Processor
The Si4731/35 implements an RDS/RBDS* processor
for symbol decoding, block synchronization, error
detection, and error correction.
The Si4731/35 device is user configurable and provides
an optional interrupt when RDS is synchronized, loses
synchronization, and/or the user configurable RDS
FIFO threshold has been met.
The Si4731/35 reports RDS decoder synchronization
status and detailed bit errors in the information word for
each RDS block with the FM_RDS_STATUS command.
The range of reportable block errors is 0, 1–2, 3–5, or
6+.
corresponding block information word contains six or
more non-correctable errors or that the block checkword
contains errors. The pilot does not have to be present to
decode RDS/RBDS.
*Note: RDS/RBDS is referred to only as RDS throughout the
4.17. Tuning
The tuning frequency is directly programmed using the
FM_TUNE_FREQ and AM_TUNE_FREQ commands.
The Si473x supports channel spacing steps of 10 kHz in
FM mode and 1 kHz in AM mode.
4.18. Seek
The Si473x seek functionality is performed completely
on-chip and will search up or down the selected
frequency band for a valid channel. A valid channel is
qualified according to a series of programmable signal
indicators and thresholds. The seek function can be
made to stop at the band edge and provide an interrupt,
or wrap the band and continue seeking until arriving at
the original departure frequency. The device sets
interrupts with found valid stations or, if the seek results
in zero found valid stations, the device indicates failure
and again sets an interrupt. Refer to “AN332: Si47xx
Programming Guide”.
More
remainder of this document.
(Si4731/35 Only)
than
six
errors
indicates
that
the
Rev. 1.0
The Si473x uses RSSI, SNR, and AFC to qualify
stations. Most of these variables have programmable
thresholds for modifying the seek function according to
customer needs.
RSSI is employed first to screen all possible candidate
stations. SNR and AFC are subsequently used in
screening the RSSI qualified stations. The more
thresholds the system engages, the higher the
confidence that any found stations will indeed be valid
broadcast stations. The Si473x defaults set RSSI to a
mid-level threshold and add an SNR threshold set to a
level delivering acceptable audio performance. This
trade-off will eliminate very low RSSI stations while
keeping the seek time to acceptable levels. Generally,
the time to auto-scan and store valid channels for an
entire FM band with all thresholds engaged is very short
depending on the band content. Seek is initiated using
the FM_SEEK_START command. The RSSI, SNR, and
AFC threshold settings are adjustable using properties.
4.19. Reference Clock
The
supporting RCLK frequencies listed in Table 13,
“Reference Clock and Crystal Characteristics,” on
page 18. Refer to Table 3, “DC Characteristics,” on
page 6 for switching voltage levels and Table 13 for
frequency tolerance information.
An onboard crystal oscillator is available to generate the
32.768 kHz reference when an external crystal and load
capacitors are provided. Refer to "2. Typical Application
Schematic" on page 19. This mode is enabled using the
POWER_UP command. Refer to “AN332: Si47xx
Programming Guide”.
The Si473x performance may be affected by data
activity on the SDIO bus when using the integrated
internal oscillator. SDIO activity results from polling the
tuner for status or communicating with other devices
that share the SDIO bus. If there is SDIO bus activity
while the Si473x is performing the seek/tune function,
the crystal oscillator may experience jitter, which may
result in mistunes, false stops, and/or lower SNR.
For
recommends that all SDIO data traffic be suspended
during Si473x seek and tune operations. This is
achieved by keeping the bus quiet for all other devices
on the bus, and delaying tuner polling until the tune or
seek operation is complete. The seek/tune complete
(STC) interrupt should be used instead of polling to
determine when a seek/tune operation is complete.
best
Si473x
Si4730/31/34/35-D60
seek/tune
reference
results, Silicon
clock
is
programmable,
Laboratories
27