User's Manual

Doc. No.: WFC006-A09
Date: 25 July, 2012
5. Theory of operation
5.1. Power Circuitry
F9195KA do not have voltage regulator. However, this application limited the host equipment, and F9195KA’s
voltage is supplied from voltage regulator of the limited host power supply. (Figure1-broken line block)
The limited host power supply contains two regulators, i.e., 5V DC/DC and 3.3V DC/DC (in Figure1)
・ 5V DC/DC supplies a regulated 5Vdc to the 3.3V DC/DC and the RF amplifier in the Wireless Part.
・ 3.3V DC/DC supplies a regulated 3.3Vdc to the Wireless LSI and the other logic IC.
5.2. Clocks
F9195KA has four clock resources.
・ Wireless LSI Reference oscillator - The default frequency for the reference oscillator is 24MHz and the
mounted crystal is a 24MHz device that meets the wireless LSI specifications.
・ 32.768kHz external Real Time Clock Module – High stability time base
・ Main CPU operates at 50MHz using internal PLL.
・ 25MHz crystal provides an accurate time base for the Ethernet PHY.
5.3. Wireless LSI - MC13224V (Figure1)
The MC13224V is a single package device that contains an ARM7 MCU, SRAM, NVM, and IEEE 802.15.4
transceiver. All of the wireless part control is done through this part and it also provides the radio function and RF
control. In this module:
・ The operating voltage is 3.3Vdc supplied from the regulator of limited host power supply.
・ The primary clock source is provided by the 24MHz crystal reference oscillator.
5.4. RF Front End Circuitry
F9195KA RF Front End circuitry is shown in Figure1. RF Front End contains the RF amplifier, the variable
attenuator, the low-pass filter and the RF switches. The MC13224 uses the RF port as a bi-directional
single-ended port for both transmit and receive. The RF Switch multiplexes TX port path and RX port path based
on the control signal of MC13224.
For the transmit path, MC13224 RF port drives the RF switch. And RF switch is enabled TX port path by the
control signal of MC14224. TX port of RF switch drives input of the variable attenuator. The variable attenuator is
a digital step attenuator covering 31 dB attenuation. Setting value of the attenuation is provided by the Main CPU.
Attenuator output drives the RF amplifier input. The RF amplifier output drives a low-pass filter. The low-pass filter
is to eliminate out-of-band spurious and harmonic signals. The low-pass filter feeds the RF switch. RF switch is
enabled TX port path by the control signal of MC13224. And then RF switch drives the antenna connector (RF
IN/OUT)
For the receive path, the incoming signal is derived from the antenna connector, and it drives the RF switch. The
RF switch is enabled RX port path by the control signal of MC13224, and the RF switch drives the RF port of the
MC13224.