SI4464 Datasheet, PDF (34/56 Pages) Silicon Laboratories – HIGH-PERFORMANCE

Si4464/63/61/60
6. Program the RSSI threshold property in the modem using “MODEM_RSSI_THRESH”.
7. Set the preamble threshold using “PREAMBLE_CONFIG_STD_1”.
8. Program the preamble timeout property using “PREAMBLE_CONFIG_STD_2”.
9. Set the sync detection parameters if enabled.
10. If needed, use “GPIO_PIN_CFG” to configure a GPIO to toggle on hop and hop table wrap.
11. Use the “START_RX” API with channel number set to the first valid entry in the hop table (i.e., the first non
0xFF entry).
12. Device should now be in auto hop mode.
5.3.1.3. Manual RX Hopping
The RX_HOP command provides the fastest method for hopping from RX to RX but it requires more overhead and
management by the host MCU. Using the RX_HOP command, the turn-around time is 75 µs. The timing is faster
with this method than Start_RX or RX hopping because one of the calculations required for the synthesizer
calibrations is offloaded to the host and must be calculated/stored by the host, VCO_CNT0. For information about
using fast manual hopping, contact customer support.
5.4. Transmitter (TX)
The Si4464/63 contains an integrated +20 dBm transmitter or power amplifier that is capable of transmitting from
–20 to +20 dBm. The output power steps are less than 0.25 dB within 6 dB of max power but become larger and
more non-linear close to minimum output power. The Si4464/63 PA is designed to provide the highest efficiency
and lowest current consumption possible. The Si4461 PA is capable of transmitting from –40 to +16 dBm. The
Si4461 PA can be optimized for either optimum current consumption (Class E) or for fine output power steps and
performance over voltage and temperature (switched-current). Switched-current matching will have fine output
power steps and more constant output power over VDD, but it will have higher current consumption than the
class-E matching. The class E will have the most efficient current consumption, but it will have more coarse output
power steps and variation across VDD. The Si4460 is designed to supply +10 dBm output power for less than
20 mA for applications that require operation from a single coin cell battery. The Si4460 can also operate with
either class-E or switched current matching and output up to +13 dBm Tx power. All PA options are single-ended to
allow for easy antenna matching and low BOM cost. Automatic ramp-up and ramp-down is automatically
performed to reduce unwanted spectral spreading.
Chip’s TXRAMP pin is disabled by default to save current in cases where on-chip PA will be able to drive the
antenna. In cases where on-chip PA will drive the external PA, and the external PA needs a ramping signal,
TXRAMP is the signal to use. To enable TXRAMP, set the API Property PA_MODE[7] = 1. TXRAMP will start to
ramp up, and ramp down at the SAME time as the internal on-chip PA ramps up/down.
The ramping speed is programmed by TC[3:0] in the PA_RAMP_EX API property, which has the following
characteristics:
TC
Ramp Time (µs)
0.0
2.0
1.0
2.1
2.0
2.2
3.0
2.4
4.0
2.6
5.0
2.8
6.0
3.1
7.0
3.4
8.0
3.7
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Rev 1.2