CXA1538 Sony Corporation, CXA1538 Datasheet - Page 11

• Manufacturer Part Number: CXA1538
• Description: FM STEREO/AM RADIO
• Manufacturer: Sony Corporation

2. MPX circuit
3. AFC circuit
4. Auto blend circuit
1) MPX load resistance
2) Time constant of de-emphasis
1) This IC has a built-in variable capacitances.
2) AFC pull-in range is expanded by increasing the capacitance of standard circuit C7 3 pF.
This IC has a built-in auto blend circuit and a MONO switch is not required as a rule. This circuit controls
the separation in proportion to the signal level and reduces noise automatically for stereo reception below
the mid electric field when the electric field strength reaches lower than about 40 dBµ. When the electric
field strength turns below 10 to 15 dBµ, MONO operation is automatically activated.
To switch MONO mode on externally, ground pin 3 with 33 kΩ.
When power supply voltage is over 3 V, change the MPX load resistor R6, R7 from 3.3 kΩ to 6.8 kΩ.
In this case, the output level is increased by about 6 dB.
Refer to the following table as the time constant is determined at C13, C14, R6 and R7.
Change to the following circuit when designing J band, because the standard circuit is for W band.
Adjust the value of capacitance according to the set specification.
50 µs
75 µs
1µ
23
9
2
0.015 µF
0.022 µF
3pF
3.3 kΩ
10
22
MONO
4.7µ
SW
150k
3
0.0082 µF
0.012 µF
33k
6.8 kΩ
1µ
C13, C14
R6, R7
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CXA1538M/N/S