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CXA3304N

Description of Operation

1) Power supply

This IC has a built-in regulator and is designed for stable operation over a wide range of supply voltages

from 2.5 to 5.5 V. Wiring to the power supply pin should be decoupled as close to the pin as possible. In

addition, the Pin 9 power supply line and the power supply line connected to the comparator output pull-up

resistor should be separated as necessary. The IC can also be set to sleep mode to reduce power

consumption by controlling Pin 14.

2) Limiter amplifier

This is a differential input type limiter amplifier. The input impedance is approximately 700

Ω. Input the IF

signal via a matching circuit.

3) RSSI circuit

This circuit outputs a current corresponding to the amplitude of the IF signal input to the limiter amplifier. If

the IF signal is the ASK signal, demodulated output is obtained. Connect a resistor to Pin 1 to convert the

voltage. Adjusting this resistance value also changes the RSSI output voltage, but the value should be set

so that the output voltage is smaller than the supply voltage –1.1 V. The output current includes a

component twice the IF signal frequency. Adjust the value of the Pin 1 external capacitor as necessary.

Connect a resistor to Pin 6 for determining the temperature characteristics of the RSSI circuit output

current.

Pin 2 is the RSSI circuit buffer output. The output range is from approximately 0.2 V to the supply voltage -

1.1 V.

4) COMP1 circuit

This is the comparator circuit for shaping the ASK demodulation signal waveform. The output is an open

collector. Connect this circuit to the power supply, etc., via a pull-up resistor. Set the connected power

supply to the Pin 9 potential or lower.

Pin 14 voltage

Function

HI

IC operation mode

LOW

Sleep mode