RDA Microelectronics, Inc.
RDA1846S Datasheet V0.1
3.2 Voice input and output
In the RX path, the voice signal after demodulation is sent to the internal DAC which can directly drive a
32Ω resistance loading through AC coupling. In the TX path, microphone signal can be sent into the chip through AC
coupling capacitors.
3.3 Synthesizer
The frequency synthesizer generates the local oscillator signal. All building blocks are fully integrated
without any external components. LO frequency can be programmed through the serial interface by the
MCU. (How to select frequency band and program LO frequency, refer to the programming guide)
3.4 XTAL Clock
The RDA1846S supports XTAL clocks such as 12.8 MHz, 13 MHz, 25.6 MHz and 26 MHz. The internal XTAL
oscillator can also be bypassed thus TCXO clock with appropriate amplitude can be sent into the chip directly. (How
to configure the internal XTAL oscillator, refer to the programming guide)
3.5 DSP functions
The DSP accomplishes the demodulation and modulation of the FM signal. Standard walkie-talkie
features such as CTS, CDS, VOX and SQ etc. are provided through the 8 GPIOs. (How to configure the
GPIOs, refer to the programming guide)
3.6 Integrated LDO
LDOs are integrated on chip which eliminates using one LDO chip on the PCB. Supply voltage for the chip is
suggested to be within 3.3V~4.8V. A common share of the supply voltage for RDA1846S and other chips or on board
circuits are not appropriate and thus not recommended.
3.7 Serial Control Interface
A 3-wire/4-wire/I2C serial interface is provided for host IC to read and write RDA1846S control registers.
(For details of the serial control interface, refer to the programming guide).
The information contained herein is the exclusive property of RDA and shall not be distributed, reproduced, or disclosed in whole or in
part without prior written permission of RDA.
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