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BB-HCM511CE/BB-HCM531CE
4.4.
Audio Block
External Microphone Jack (CN505)
Used with the external microphone.
Used with the external microphone.
Audio Output (CN504)
Used when connecting a speaker with a built-in amplifier, when the audio is output from a camera.
Used when connecting a speaker with a built-in amplifier, when the audio is output from a camera.
Microphone Detection (Q501)
When the external microphone plug is not inserted, pins 3 and 2 of the Microphone Jack (CN505) are short-circuited and a base
current is supplied to Q501 through R501, R506 and R505 so that the Q501 goes ON and a collector (MIC_S signal) goes LOW.
Alternatively, when the microphone plug is inserted, pins 3 and 2 of the CN505 become open so that the Q501 goes OFF and
the MIC_S signal goes HIGH. From this signal, the CPU detects the microphone status.
The CPU turns the microphone SW on and off in the PCM Codec (IC501) for the external or the built-in microphone, as appro-
priate.
When the external microphone plug is not inserted, pins 3 and 2 of the Microphone Jack (CN505) are short-circuited and a base
current is supplied to Q501 through R501, R506 and R505 so that the Q501 goes ON and a collector (MIC_S signal) goes LOW.
Alternatively, when the microphone plug is inserted, pins 3 and 2 of the CN505 become open so that the Q501 goes OFF and
the MIC_S signal goes HIGH. From this signal, the CPU detects the microphone status.
The CPU turns the microphone SW on and off in the PCM Codec (IC501) for the external or the built-in microphone, as appro-
priate.
ALC Amplifier (IC602: For the built-in microphone, IC603: For the external microphone)
Power Supply: 3.3V
Amplifier for Auto Level Control
Power Supply: 3.3V
Amplifier for Auto Level Control
PCM Codec (IC601)
Power Supply Voltage: 3.3V
Clock Frequency: Contains a built-in PLL function and generates a clock from the BCLK (256 KHz).
Contains an amplifier, LPF, gain adjustment, AD/DA converter, host I/F, PCM serial I/F and speaker output function.
Power Supply Voltage: 3.3V
Clock Frequency: Contains a built-in PLL function and generates a clock from the BCLK (256 KHz).
Contains an amplifier, LPF, gain adjustment, AD/DA converter, host I/F, PCM serial I/F and speaker output function.
Flow of audio Signal
[Microphone audio]
[Microphone audio]
1. The audio signal input from pin 1 of the built-in microphone connector (CN501) is amplified by the amplifier in the PCM Codec
(IC501) and the ALC (IC502), then input as the built-in microphone to the PCM Codec (IC501) again.
When the level of the input audio signal is more than the specified value, the gain is changed and the output signal level is
kept constant at the ALC (IC502). Audio distortion is controlled when the input is excessive.
When the level of the input audio signal is more than the specified value, the gain is changed and the output signal level is
kept constant at the ALC (IC502). Audio distortion is controlled when the input is excessive.
2. When the external microphone is attached to the microphone jack (CN505), the audio signal input from pin 2 of the CN505 is
amplified by the amplifier in the PCM Codec (IC501) and the ALC (IC503), then input as the external (microphone) to the PCM
Codec (IC501) again
The ALC (IC503) works in the same way as the IC502.
Codec (IC501) again
The ALC (IC503) works in the same way as the IC502.
3. In the PCM Codec (IC501), after the audio signal is switched between the built-in microphone and the external microphone by
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