THEORY OF OPERATION: Global Control Audio Power II (GCAP II) Circuitry
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8-bit D/A converter
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10-channel, 8-bit A/D converter
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Square-wave output to generate negative supply voltages
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Control logic
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Audio CODEC with serial interface
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Earpiece amplifier
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Speaker amplifier
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Alert amplifier
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Two microphone amplifiers
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Auxiliary amplifier
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Sim card level shifters
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Serial peripheral interface (SPI)
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DSC-bus buffers
The GCAP II IC has the following specifications:
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Multiple lithium-ion cell input configuration
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Shutdown current: 10µA maximum
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Standby current mode: 400µA
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Internal PMOS pass devices
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Serial peripheral interface read/write interface
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Auxiliary battery switch control
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100-pin dual die QFP IC package
The GCAP II IC is designed to support the needs of portable cellular telephone
products. It provides the necessary control, audio, and regulator functions. The
following functions are provided:
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Turn on control signals to properly activate the unit
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Turn off control signals to turn off the unit if an error is detected
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Audio amplification for the speaker
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Audio amplification for the alert
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Audio amplification for the external audio
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Audio amplification of the microphone
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13-bit linear audio CODEC
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Band-gap reference voltage
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Linear regulation of DC voltages
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Two BUCK/BOOST switching regulators
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Operational amplifiers for use in the battery charger
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Internal D/A conversion for the battery charger